IR CPL PREP COURSE
DAY2 - PBN
ADAM STAWCZYK
AGENDA
- PBN concept
- RNAV and RNP
- Requirements of specific RNAV and
RNP specifications
- RNAV10
- RNAV5
- RNAV1, RNP1 / 2 SIDs and STARs
- RNP4
- Augmentation sys.: ABAS, SBAS, GBAS
- RNP APCH
- RNP AR APCH
- A-RNP
- PinS
PBN
Navigation application
A Navigation Specification is a set of aircraft and aircrew requirements needed to support
a Navigation Application within a defined airspace concept.
The Navigation Application refers to the application of the navigation specification
and Navaid Infrastructure in the context of an airspace concept regarding ATS routes and
instrument flight procedures.
Navigation Applications cannot be realised without a Navaid Infrastructure. Unlike 50
years ago, the Navaid infrastructure is now both space- and ground-based.
The ground-based infrastructure refers to the conventional navigation aids such as NDB
(Non-Directional Beacon), VOR (Very High Frequency Omni-directional Range), DME
(Distance Measuring Equipment) as well as ILS (Instrument Landing System) and
MLS (Microwave Landing System).
The space-based infrastructure refers to satellites in orbit around our planet. The generic
name for any satellite constellation (and the augmentation systems) used for positioning and
time is GNSS (Global Navigation Satellite System). The EUROCONTROL work on navigation
infrastructure supports the deployment of GNSS while ensuring that conventional navigation
aids evolve from a primary role to provide redundant services to GNSS.
CONVENTIONAL AIRWAYS VS. RNAV AIRWAYS
CONVENTIONAL AIRWAYS
RNAV AIRWAYS
•Inefficient
•Free routing possible
•Concentration of aircraft over the beacon
•More flexible routing
In conventional navigation, the aircraft is routed in straight lines which join existing
ground based radio navigation aids. Typically these are VOR/DME’s although NDB’s
may also be used. The routes between navigation aids are designated as airways.
This is inefficient as the aircraft must follow routes which are determined by the
ground based navigation infrastructure.
With the introduction of modern avionics it became possible to determine the
aircrafts position based on the input of several radio aids, and calculate the
trajectory required to route directly along the chosen route. This meant aircraft
were free to operate in more efficient ways by routing straight through the area of
operation – ''Area Navigation".
Area navigation (RNAV) is a method of IFR navigation that allows an aircraft to choose
any course within a network of navigation beacons, rather than navigate directly to
and from the beacons. This can conserve flight distance, reduce congestion, and allow
flights into airports without beacons. Area navigation used to be called "random
navigation", hence the acronym RNAV.
RNAV can be defined as a method of navigation that permits aircraft operation on any
desired course within the coverage of station-referenced navigation signals or within
the limits of a self-contained system capability, or a combination of these.
Area navigation (RNAV) equipment includes VOR/DME, DME/DME, LORAN C, GNSS,
and inertial navigation systems (INS).
NDB’s cannot be used with RNAV.
Some aircraft may have equipment that allows input from more than one RNAV
source, thereby providing a very accurate and reliable navigation source.
Modern FMS is capable to use multi RNAV sensors,
i.e. if GNSS fails it switches automatically to DME/DME, or INS.
RNAV equipment is capable of computing the aircraft position, actual track,
groundspeed, and then presenting meaningful information to the pilot. This information
may be in the form of distance, cross-track error, and time estimates relative to the
selected track or WP. In addition, the RNAV equipment installations must be approved for
use under IFR. The Airplane Flight Manual (AFM) should always be consulted to
determine what equipment is installed, the operations that are approved, and the details
of equipment use.
History of RNAV - LORAN
In the United States, RNAV was developed in the 1960s, and the first such routes were
published in the 1970s. Various types of ground-based RNAV systems have been available
from that time. These were originally dependent on VLF/Omega and LORAN ‘C’ long
range radio signals.
LORAN (LOng RAnge Navigation) was developed in the United States during World War II.
It was the dominant system of long-range electronic navigation from 1943 until the
widespread use of the Global Positioning System in the late 1990s. LORAN-C emerged in
the late 1950s with the advent of improved timing equipment at LORAN stations. The TI
9100 was a milestone because the "microprocessor revolution" of the early 1980s
permitted the automation of many LORAN-C functions that limited its practicality for
single pilot use. It also significantly reduced size, power consumption, weight, and cost.
History of RNAV - VOR/DME
More recently RNAV moved to position derived from VOR radials (up to 62nm slant distance) and/or DME
distances. VOR RNAV is based on information generated by the present VORTAC or VOR/DME system to create a
WP using an airborne computer. As shown in Figure below, the value of side A is the measured DME distance to
the VOR/DME. Side B, the distance from the VOR/DME to the WP, and angle 1 (VOR radial or the bearing from the
VORTAC to the WP) are values set in the flight deck control. The bearing from the VOR/DME to the aircraft, angle
2, is measured by the VOR receiver. The airborne computer continuously compares angles 1 and 2 and determines
angle 3 and side C, which is the distance in NMs and magnetic course from the aircraft to the WP. This is
presented as guidance information on the flight deck display.
Most VOR/DME RNAV systems have the following airborne controls:
1. OFF/ON/Volume control to select the frequency of the VOR/DME station to be used.
2. MODE select switch used to select VOR/DME mode, with: a. Angular course width deviation
(standard VOR operation); or b. Linear cross-track deviation as standard (±5 NM full scale CDI).
3. RNAV mode, with direct to WP with linear cross-track deviation of ±5 NM.
4. RNAV/APPR (approach mode) with linear deviation of ±1.25 NM as full scale CDI deflection.
5. WP select control. Some units allow the storage of more than one WP; this control allows
selection of any WP in storage.
6. Data input controls. These controls allow user input of WP number or ident, VOR or LOC
frequency, WP radial and distance.
KING KNS80 RNAV VOR/DME PANEL
The advantages of the VOR/DME RNAV system is the ability of the airborne
computer to locate a WP wherever it is convenient, as long as the aircraft is within
reception range of both nearby VOR and DME facilities. A series of these WPs
make up an RNAV route. In addition to the published routes, a random RNAV route
may be flown under IFR if it is approved by air traffic control (ATC). The limitation
of this system is the reception volume. Published approaches have been tested to
ensure this is not a problem. Descents/approaches to airports distant from the
VOR/DME facility may not be possible because, during the approach, the aircraft
may descend below the reception altitude of the facility at that distance.
History of RNAV - DME/DME
After VOR/DME concept was developed, next concept was introduced to develop
a DME/DME positioning system. The position accuracy is dependent on the stations geometry
and the distance measurement errors, which is highly accurate. To get the best performance
from the system, station geometry should be controlled. Integration of DME/DME navigation
with other navigation systems, such as GNSS, is also an interesting future research and would
help to reduce the position bias. The interrogator performs the complete search/tracking
procedure before switching to the next ground station channel in a positioning rate of about 0.2
Hz.
A DME/DME fix can provide a position accurate to within 0.2 nm, however there are limitations on
when this can be used. The indicated distance from a DME contains a small error, shown here as the
dotted white lines either side of the indicated distance. The blue area indicates the area within
which the actual position of the aircraft is contained. The fix is most accurate when the angle of cut –
the angle at which the two range arcs meet – is 90 degrees, this provides the smallest error region.
Where the angle of cut is too large (in this example it is 180 degrees) the uncertainty in the actual
position becomes unacceptably large, seen here in the larger orange area. For this reason a
DME/DME fix can only be used with an angle of cut of between 30 and 150 degrees. The specialist
tasked with designing the navigation application will take this limitation into account.
DME/DME usage is limited by the infrastructure on the ground. In some
areas extensive DME coverage makes it suitable as a navigation aid. It is
important to note that in this case any failure of a required DME could
make the PBN application unusable since it would reduce the radio aid
coverage below that which is required for accurate position fixing. This
should be indicated by NOTAM.
History of RNAV - INS/IRS (IRU)
An inertial navigation system (INS) is used on some large aircraft for long range navigation. This may
also be identified as an inertial reference system (IRS), although the IRS designation is generally
reserved for more modern systems. An INS/IRS is a self contained system that does not require input
radio signals from a ground navigation facility or transmitter. The system derives attitude, velocity,
and direction information from measurement of the aircraft’s accelerations given a known starting
point. The location of the aircraft is continuously updated through calculations based on the forces
experienced by INS accelerometers. A minimum of two accelerometers is used, one referenced to
north, and the other referenced to east. In older units, they are mounted on a gyro-stabilized
platform. This averts the introduction of errors that may result from acceleration due to gravity.
lNS/IRS (IRU) can be used for RNAV to maintain prior tracking for up to 2 hours. After that time, in
order to maintain RNAV requirements, update of initial position shall be made.
An INS uses complex calculation made by an INS computer to convert applied forces into
location information. An interface control head is used to enter starting location position data
while the aircraft is stationary on the ground. This is called initializing. From then on, all motion
of the aircraft is sensed by the built-in accelerometers and run through the computer. Feedback
and correction loops are used to correct for accumulated error as flight time progresses. The
amount an INS is off in one hour of flight time is a reference point for determining performance.
Accumulated error of less than one mile after one hour of flight is possible. Continuous accurate
adjustment to the gyro-stabilized platform to keep it parallel to the Earth’s surface is a key
requirement to reduce accumulated error. A latitude/longitude coordinate system is used when
giving the location output.
INS is integrated into an airliner’s flight management system and automatic flight control system.
Waypoints can be entered for a predetermined flightpath and the INS will guide the aircraft to
each waypoint in succession. Integration with other NAV aids is also possible to ensure
continuous correction and improved accuracy but is not required. Modern INS systems are
known as IRS. They are completely solid-state units with no moving parts. Three-ring, laser gyros
replace the mechanical gyros in the older INS platform systems. This eliminates precession and
other mechanical gyro shortcomings. The use of three solid-state accelerometers, one for each
plane of movement, also increases accuracy. The accelerometer and gyro output are input to
the computer for continuous calculation of the aircraft’s position.
Modern micro-IRS unit with built in GNSS module
The most modern IRS integrate is the GNSS. The GNSS is extremely accurate in itself. When combined
with IRS, it creates one of the most accurate navigation systems available. The GNSS is used to
initialize the IRS so the pilot no longer needs to do so. GNSS also feeds data into the IRS computer to
be used for error correction. Occasional service interruptions and altitude inaccuracies of the GNSS
system pose no problem for IRS/GNSS. The IRS functions continuously and is completely self
contained within the IRS unit. Should the GNSS falter, the IRS portion of the system continues
without it. The latest electronic technology has reduced the size and weight of INS/IRS avionics units
significantly. Modern micro-IRS unit measures approximately 6-inches on each side.
History of RNAV - GNSS
As RNAV accuracy has improved, it has begun to play a vital role in increasing ATM
efficiency whilst also sustaining safety performance. Last innovation in RNAV was
introduction of GNSS, as stand-alone system.
Garmin GPS 155 Receiver
The GPS 155 was the first Global Positioning System (GPS) receiver certified for U.S.
operation in Instrument Flight Rules (navigating only by instruments). This certification
marked the move toward a single GPS-centered navigational and surveillance system for
air traffic control.
History of RNAV in Europe
B-RNAV - 1998:
In Europe, Basic Area Navigation (B-RNAV, now known as RNAV5) has been introduced. It
is in use since 1998 mandated for aircraft using higher level airspace. It requires a
minimum navigational accuracy of +/- 5nm for 95% of the time (this is why it is named
RNAV5) and is not approved for use below MSA. Initially it was used for en-route phases
of the flight only. Later, it stared to be used within TMAs for Arrivals and Departures.
P-RNAV - 2001:
European standards for Precision Area Navigation (P-RNAV) are now also defined - a
navigational accuracy of +/- 1nm for 95% of the time and the ability to fly accurate tactical
offsets, the removal of the ability of a flight crew to add waypoints and the requirement to
link the R-NAV system to the FMS/Autopilot. This level of navigation accuracy can be
achieved using DME/DME, VOR/DME or GNSS.
It can also be maintained for short periods using IRS (the length of time that a particular IRS
can be used to maintain P-RNAV accuracy without external update is determined at the
time of equipment certification). It should be noted that if GNSS is not used as a source
then two independent ground-based sources are required to meet P-RNAV minimum
requirements apart from specified short periods of INS ‘backup’, which is a more stringent
requirement than for some older FMS.
P-RNAV is close to RNAV 1, however in Europe, the main difference between P-RNAV and
RNAV 1 is that P-RNAV permits the use of VOR/DME in limited circumstances.
P-RNAV revolutionized the way we fly today. Thanks to greater accuracy, TMAs could
be designed to occupy less airspace, but also enabling increase of traffic within the
TMA. Controllers are giving much less voice instructions, pilots are very rearly
recieving radar vectors!
PBN concept - general view
ICAO published its PBN concept in 2008 by publishing ICAO Doc. 9613 (PBN Manual). Note, PBN
Manual was published 10 years later, after B-RNAV concept was introduced in Europe.
To improve safety of operations, ICAO developed new concept and called it Required Navigation
Performance (RNP). RNP did not substitute RNAV. It is an additional specification. The most basic
difference between RNAV and RNP is that RNP requires on-board performance monitoring and
alerting.
PBN Manual replaced the previous RNP Manual and now holds both specifications:
RNAV and RNP within the PBN Manual. The PBN Concept aims to streamline RNAV
and RNP applications on a global basis by reducing the number of navigation
specifications in use worldwide and thus enhancing safety, improving
interoperability and reducing costs for operators. To these ends, the PBN manual
includes a limited set of PBN specifications for worldwide use in different phases of
flight.
PBN - RNAV and RNP
https://www.youtube.com/watch?v=KpkmYFJRHIM&feature=youtu.be
There are 2 main components of PBN:
RNAV and RNP
RNAV:
RNAV enables aircraft to fly on any desired flight path within the coverage of
ground- or space-based navigation aids, within the limits of the capability of the
self-contained systems, or a combination of both capabilities. As such, RNAV aircraft
have better access and flexibility for point-to-point operations.
RNP:
RNP is RNAV with the addition of an on-board performance monitoring and alerting
capability. A defining characteristic of RNP operations is the ability of the aircraft
navigation system to monitor the navigation performance it achieves and inform the
crew if the requirement is not met during an operation. This onboard monitoring
and alerting capability enhances the pilot's situational awareness and can enable
reduced obstacle clearance or closer route spacing without intervention by air traffic
control.
Certain RNP operations require advanced features of the onboard navigation function and approved training and
crew procedures. These operations must receive approvals that are characterized as RNP Authorization Required
(RNP AR) Operations.
The illustrations above depict the constraints associated with conventional, ground-based sensor specific
routes/procedures and the flexibility and benefits of performance-based, non-sensor specific navigation (both
RNAV and RNP).
Once the required performance level is established, the capability of the different aircraft determines whether it
can safely achieve the specified performance and qualify for the operation.
PBN:
RNAV sensor:
RNP sensors:
- VOR/DME
- DME/DME
- INS/IRS
- GNSS
- LORAN C
- GNSS + augmentation
Used for En-route & terminal proc.
Used for final approaches.
The PBN concept specifies that aircraft RNAV and RNP system
performance requirements be defined in terms of:
- Accuracy
- Integrity
- Availability
- Continuity
Accuracy: The accuracy of an estimated or measured position is its degree of
conformance with a real position.
Availability: percentage of time that the services of the system are usable by the
navigator. (Alt: proportion of time during which reliable navigation information is
presented to the crew, autopilot, or other system managing the flight of the aircraft).
The availability of a system (or service) establishes the percentage of time during when
the operation (for example a final approach) can be started.
Continuity: the capability of the system to perform its function without unscheduled
interruptions during the intended operation. (Alt from ICAO SARPS: It relates to the
capability of the navigation system to provide a navigation output with the specified
accuracy and integrity during the approach, assuming that it was available at the start of
the operation).
The continuity of the system guarantees that once an operation (for example a final
approach) is initiated, it will not be interrupted.
Integrity: a measure of the trust that can be placed in the correctness of the
information supplied. The parameters defining the integrity are specific to navigation
specifications:
▪ Alert Limit (AL): the error tolerance not to be exceeded without issuing an
alert. Means the region (horizontal and vertical) which is required to contain the
indicated position with the required probability for a particular navigation
mode. Required ALs depend on the type of operation.
• Time to Alert: the maximum allowable time elapsed from the onset of the navigation
system being out of tolerance until the equipment enunciates the alert
• Integrity Risk: probability that, at any moment, the position error exceeds the Alert
Limit.
• Protection Level: statistical bound error computed so as to guarantee that the
probability of the absolute position error exceeding said number is smaller than or
equal to the target integrity risk. Means the region (horizontal and vertical) assured
to contain the indicated position. It defines the region where the missed alert
requirement can be met. PLs are computed by the on board receiver.
If during an operation the PLs exceed the required ALs, the operation cannot continue.
Factors effecting navigation performance:
• Navigation System Error (NSE) -> position uncertainty due to navigation system and
avionics.
• Flight Technical Error (FTE) components –> Raw data manual flying skills, F/D manual
flying, F/D+A/P.
• Database integrity (Path Definition Error components).
Flight Technical Error
• FTE may be monitored automatically (cross-track monitoring in various forms: CDI,
MAP, FMC readout)
• Usually the information is presented visually to the pilot, however it may be in form
of text:
Cross-track error (XTK) 0.21NM LEFT - shown on FMGC (A320)
Cross-track error (XTK) 0.2NM LEFT - shown on MAP MODE
Cross track (XTK) presented on top of MFD G1000
Cross track (XTK) presented on HSI PFD G1000
Navigation System Error:
- The actual NSE is unknown
- Estimates are often given by Navigation Systems
• Actual Navigation Performance (ANP)
• Estimated Position Uncertainty (EPU)
PBN Fundamental Requirement:
• TSE < Required Accuracy at least 95% of the time
• FTE is easier to monitor, and should be kept to a minimum: - Maintain center line
• FTE monitored by crew, procedure based on display scaling - Effective threshold: ½
full scale deflection
• NSE is typically small, but difficult to determine
• Typically the TSE is significantly smaller than the required accuracy
PBN guidance
If you take conventional ILS, it provides both lateral and vertical guidance along the
final approach path by means of a localizer and glideslope beam, respectively. The
localizer and the glideslope provide a straight final approach segment that is tracked for
about five nautical miles prior to touchdown. Also noteworthy is the fact that the
localizer and the glideslope signals are angular, and change in width as the aircraft
approaches the runway. This, in turn, causes the onboard guidance equipment to have
variable sensitivity and requires variable control gains from the pilot or autoflight
system. Figure below illustrates the angular nature of the glideslope beam, which
guides the aircraft along a prescribed glidepath.
In PBN approaches the lateral and vertical guidance is instead computed by the aircraft
Flight Management System (FMS), which usually relies on GNSS, or other sensors. PBN
operations may provide "ILS alike" angular deviations for a pilot, or linear ones,
depanding on system used and phase of the flight.
• For Oceanic/remote, en-route and terminal operations, PBN is limited to operations
with linear lateral performance requirements and time constraints..
• For Approach operations, PBN accommodates both linear and angular laterally guided
operations.
Stand alone GNSS accuracy vs. Augmented systems
Stand alone GNSS will not provide you enaugh accuracy due to its design, mainly due to
"Time-shift error". To obtain better accuracy, additional system needs to be introduced,
so called: "AUGMENTATION SYSTEM".
AUGMENTATION SYSTEMS
AAIM (Aircraft Autonomous Integrity Monitoring)
The type of ABAS using addition information from on-board sensors is
named AAIM (Aircraft Autonomous Integrity Monitoring).
Typical sensors used are barometric altimeter, clock and inertial navigation system.
Barometric altimetry sources are used sometimes to improve the TTFF (Time to First
Fix), which refers to the time required to acquire satellite signals and navigation data
and calculate a position solution
RAIM (Receiver Autonomous Integrity Monitoring)
• A receiver must lock on to 4 satellites simultaneously, to provide a more or less
accurate position.
• RAIM is a separate, or receiver built-in device, that allows the receiver lock on to more
than 4 satellites.
• It compares the position results, when computing 5 different positions, using a
different combination of satellite inputs, for each position calculation.
By comparing the 5 calculated positions, using signals from 5 different combinations of
satellites, the RAIM can MATHEMATICALLY determine that 1 satellite no longer provides
accurate positioning data = FAULT DETECTION (FD)
By involving the signal from 6 different combinations of satellites, the RAIM can
MATHEMATICALLY determine WHICH satellite no longer provides accurate positioning
data = EXCLUSION (E)
• 4 satellites are needed for POSITIONING.
• 5 satellites are needed for FAULT DETECTION (FD).
• 6 satellites are needed for FAULT DETECTION (FD) and EXCLUSION (FDE).
• Older RAIM systems only had FD-functionality, more modern systems have FDE
(and can isolate which satellite is no longer providing accurate signals).
• RAIM/AAIM (ABAS) were the first type of augmentations systems, by
monitoring INTEGRITY of the GNSS (GPS)-satellites.
• Modern built-in RAIM/AAIM systems nowadays provide comparable overall
positioning accuracy as the EGNOS-system (SBAS).
Space Based Augmentation System
A separate satellite system (NOT a GNSS-constellation on its own!), that uses the signals
of GNSS constellations (GPS, Glonass, or Galileo) and enhances their ACCURACY. SBAS
satellites send corrective messages to receivers containing corrections regarding GNSSsatellite signals and their deviations, to the receivers.
6 systems are currently in use (or development):
• European Geostationary Navigation Overlay Service (EGNOS) Europe
• Wide Area Augmentation System (WAAS) USA with its Canadian Region CWAAS
• System of Differenctial Correction and Monitoring (SDCM) Russia
• Multi-functional Satellite Augmentation System (MSAS) Japan
• GPS Aided Geo Augmented Navigation (GAGAN) India
• Satellite Navigation Augmentation System (SNAS) China
Wide Area Augmentation System
Developed by FAA (Federal Aviation Administration), main-ly to enhance the
ACCURACY of GPS-signals, especially for air-borne receivers.
The focus lies heavily on the domestic area (USA), but neigh-boring areas are also
covered.
The WAAS system uses ground based REFERENCE STATIONS to establish corrections of
GPS-satellites.
These are sent to calculation stations and uploaded to the WAAS satellites who than
forward it to receivers.
According to its own accuracy statement, the accuracy provided by GPS/WAAS is
within 8 meters during 95% of the time.
WAAS is designed to improve the accuracy, integrity, and availability of GPS signals. WAAS allows GPS to be used as
the aviation navigation system from takeoff through Category I precision approaches.
WAAS covers a more extensive service area in which surveyed wide-area ground reference stations are linked to
the WAAS network. Signals from the GPS satellites are monitored by these stations to determine satellite clock and
ephemeris corrections. Each station in the network relays the data to a wide-area master station where the
correction information is computed.
A correction message is prepared and uplinked to a geostationary satellite (GEO) via a ground uplink and then
broadcast on the same frequency as GPS to WAAS receivers within the broadcast coverage area. In addition to
providing the correction signal, WAAS provides an additional measurement to the aircraft receiver, improving the
availability of GPS by providing, in effect, an additional GPS satellite in view. The integrity of GPS is improved
through real-time monitoring, and the accuracy is improved by providing differential corrections to reduce errors.
As a result, performance improvement is sufficient to enable approach procedures with GPS/WAAS glidepaths.
At this time the FAA has completed installation of 25 wide area ground reference systems, two master stations,
and four ground uplink stations. General Requirements WAAS avionics must be certified in accordance with TSOC145A, Airborne Navigation Sensors Using the GPS Augmented by the WAAS; or TSO-146A for stand-alone
systems.
WAAS receivers support all basic GPS approach functions and provide additional capabilities with the key benefit
to generate an electronic glidepath, independent of ground equipment or barometric aiding. This eliminates
several problems, such as cold temperature effects, incorrect altimeter setting, or lack of a local altimeter source,
and allows approach procedures to be built without the cost of installing ground stations at each airport. A new
class of approach procedures, which provide vertical guidance requirements for precision approaches, has been
developed to support satellite navigation use for aviation applications. These new procedures called Approach
with Vertical Guidance (APV) include approaches such as the LNAV/ VNAV procedures presently being flown with
barometric vertical navigation.
Using 3 geostationary satellites, WAAS covers all of the United States (-1) and large
portions of Canada, Alaska and Mid-America at optimum level.
Actual accuracy provided by the combination GPS, with WAAS appears to be within 1
meter horizontally and 1,5 meter vertically for all of the US, parts of Canada & Alaska.
EGNOS - European Geostationary Navigation Overlay Service
The EGNOS/WAAS principles are quite similar:
• They both are intended to augment ACCURACY and monitor INTEGRITY of the GNSS signals,
using geo-stationary satellites for transmission of the corrective missions to the receivers;
• EGNOS uses ground stations (RIMS) for determination of inaccuracies in GPS-signals (and
hopefully in the future also Galileo-signals), these are forwarded to Control Centers (MCC)
and uploaded to the geostationary satellites via parabolic antennas (NLES).
EGNOS consists of 3 geostationary satellites, that provide corrective messages from space to the
GNSS-receivers.
• Global coverage is hard with geostationary satellites only.
• There are always blind spots, especially near the poles, as the satellites orbit around the Equator.
RIMS = Ranging & Integrity Monitoring Stations
MCC = Master Control Center
NLES = Navigation Land Earth Stations
LPV and LP use SBAS
There are 2 types of PBN approaches that use SBAS:
•LPV (localizer performance with vertical guidance) - 3D system
- DH: 200ft
- Meets criteria for CAT1 approach - RVR 550m
- Flown like an ILS
- It is an APV or PA (later about it)
•LP - 2D system
- DH: 250ft
- It is an NPA
- Flown like LOC/DME approach
https://www.youtube.com/watch?v=oxWm81YHPlg&feature=youtu.be
GBAS – Ground based Augmentation System
GBAS,or Ground-based Augmentation
Systems use fixed GNSS-receiver
stations, with an accurately known
fixed position on Earth (Reference
Receivers).
These compare the signals/positions
obtained by the various GNSSsatellites in sight and emit
“corrections” of their errors to
receivers in the vicinity.
This way the other receivers can
augment their position determination
and increase the ACCURACY of
position.
In USA, GBAS is called “LAAS”, or
Local Area Augmentation System.
GBAS consists of several REFERENCE RECEIVERS, that gathers a GPS signal and
compare the satellite’s based position data, to their own, exactly known position.
The differences are computed and passed on to the
receivers in the area, to enhance their accuracy.
A separate antenna communicates the deviations, observed
for all GNSS-satellites, as an “image”, to receivers in the
area.
This signal is known as the VDB: VHF
Data Broadcast
REFERENCE RECEIVER
The message contains mathematical
deviations and necessary corrections
(for X, Y and Z) so receivers can
calculate more accurate positions
GBAS VHF Data Broadcast antenna
GBAS is intended to provide precision runway approaches up to CAT IIIC - type of approach that uses GBAS is
called GLS.
Today Europe is in the process of certifying GLS precision approaches using GBAS as augmentation, as only
navigation aid. The 1st European GBAS approach was certified for CAT I operations in 2012: Bremen GLS RWY
09/27
The difference between GBAS and SBAS, is that for GBAS, there is no link via geostationary satellites.
This allows GBAS to have a quicker reaction time (increased INTEGRITY), but reduced range.
GBAS requires “line of sight”, for the VHF-signal. This largely reduces the range = 1,23 x (√height aircraft + √
station elevation), to +/- 200 km.
https://youtu.be/J8iRdgr9MQk
RNAV & RNP
Light blue color represents PBN specification that does not require any additional approval from the operator. Of course, aircraft needs
to meet technical requirements of given specification and pilot needs to be trained to perform certain PBN applications. IR PBN rating in
the pilot's license is enough to use a given specification.
Dark blue color represents specifications that require special authorization given by the CAA to the operator. This approval is valid only
for a given approach/runway combination. Aircraft needs to be properly equipped, crew needs to be trained to perform a given
approach for a given runway.
The PBN specifications for which the aircraft complies with the relevant
airworthiness criteria are set out in the AFM, together with any limitations to be
observed.
RNAV X
RNP X
The expression “X” means the aircraft can follow a pre-defined track (lateral
navigation) with X Nautical Miles (NM) accuracy 95% of the flight time by the
population of aircraft operating within the airspace, route or procedure.
Because functional and performance requirements are defined for each navigation
specification, an aircraft approved for an RNP specification is not automatically
approved for all RNAV specifications. Similarly, an aircraft approved for an RNP or
RNAV specification having a stringent accuracy requirement (e.g. RNP 0.3
specification) is not automatically approved for a navigation specification having a
less stringent accuracy requirement (e.g. RNP 4).
RNAV and RNP specifications include requirements for certain
navigation functionalities. At the basic level, these functional
requirements may include:
• Continuous indication of aircraft position relative to track to be
displayed to the pilot flying on a navigation display situated in
his primary field of view;
• Display of distance and bearing to the active (To) waypoint;
• Display of ground speed or time to the active (To) waypoint;
• Navigation data storage function; and
• Appropriate failure indication of the RNAV or RNP system,
including the sensors.
Due to advances in satellite navigation and area navigation we now have new approaches:
Approach procedure with vertical guidance (APV)
• Lateral and vertical guidance;
• Good navigation accuracy;
• Minimum: DA/H.
ICAO new approach classification
As shown above, blue dashed line represents Non Precision Approaches with
Pilot Derived Decision Altitude (DDA) that according to EASA regulations shall be flown
with CDFA - Continous Descent Final Approach technique.
Since aircraft must not descend even 1 ft below MDA, if visual reference is not
established, correct DA must be used. MDA is depicted as DA on Jeppesen charts
nowadays, but this altitude is still the “old” MDA with no margin for height loss during
initiation of go around. Thus higher DA must be briefed and used, so called DDA –
Derived Decision Altitude.
The DDA applies to all NPAs. It does not apply to APVs (approaches with vertical
guidance) like LNAV/VNAV, LPV, RNP AR APCH and precision approaches such as ILS, LPV,
GLS. Those approaches already incorporate the possible height loss in case of a go
around. On many airliners this altitude incremement is 50ft, however due to much
smaller size and less momentum of Tecnam P2006T, Bartolini Air establishes this
increment to be 30ft (RYR students use 40ft).
DDA = published DA/MDA + 30ft
New generation
aeroplanes like 737 MAX,
A350 and 787 are
capable of LPV and GLS.
Majority of current airliners are only LNAV/VNAV certified. However, new Airbus A220,
A350, Boeing 787, 737MAX are also LPV and GLS equipped.
The lowest value of the minimums you may receive with GLS - GBAS LANDING SYSTEM.
As it uses ground installation, it could be certified to CATI, CATII and CATIII.
As shown on ICAO Approach Classification, LPV - Localizer Performance with Vertical
guidance could be either PA - Precision Approach, or APV - Approach with Vertical
guidance. It depends on the runway's approach lighting system used. If it is FALS - Full
Approach Light System (more than 720m in length), then LPV could be certified to CATI
minimums (RVR550m, DH200ft). If the approach lights are not FALS, then LPV could only
be certified as APV with DH not lower than 250ft and RVR not lower than 750m. LPV
uses SBAS.
LNAV/VNAV system is using barometric altimeter + ABAS in order to calculate vertical
guidance. Due to temperature error it cannot obtain CATI accuracy. That is why
LNAV/VNAV minimums are higher than LPV.
The highest minimums we obtain with LP - Localizer performance without vertical
guidance (that is supported by SBAS) and LNAV operation. We treat them as NPA - non
precision approaches.
ARINC424 Specification
ARINC424 is an aeronautical specification developed and maintained by the industry
which has been used for the exchange of navigation and communication data between
commercial data suppliers and avionic system manufacturers for more than 30 years
It was created in the 70’s to meet the requirements of more complex embedded
navigation systems (FMS) supporting evolving navigation techniques. The ARINC424
sets forth the air transport industry’s recommended standards for the preparation of
airborne navigation system reference data files.
The first issue of the ARINC424 specification was officially published in May 1975. The
version applicable in August 2010 is version 19, which was released on December 2008.
The specification is maintained by the A424 committee which groups the major
aeronautical actors involved in the different steps of the data production chain:
AIRAC
AIRAC stands for Aeronautical Information Regulation And Control. It isan internationally
agreed upon series of common dates for States to publish aeronautical information.
AIRAC originates in ICAO Annex 15, which covers Aeronautical Information Services, and
dates back to 1964. The idea is simple. Participating counties issue changes to
aeronautical information on the same 28-day cycle. Imagine the mess an area like Europe
would be if each country decided to update information on different schedules. In fact, in
1999 at least 20 safety incidents in Europe were attributed to AIRAC non-adherence.
Annex 15 includes a list of what should be covered by AIRAC. Some of the items are
holding and approach procedures, arrival and departure procedures, noise abatement
procedures, any other pertinent ATS procedures, transition levels, transition altitudes,
minimum sector altitudes, runways, stopways, ground operating procedures (including
low visibility procedures), approach and runway lighting and aerodrome operating
minima (if published by a State).
Fundamentally, AIRAC is a quality control process to ensure coordination of changes
within the global airspace system. It ensures everyone is playing from the same sheet of
music when it comes to aviation information.
Before the database is loaded into your FMC, it needs to undergo specific compliance
procedure. The database is prepared every AIRAC cycle by the navigation equpment
providers. The database content is stored in various forms on protable discs/cards. Only
approved personnel within the operator is allowed to load the database into the FMC.
Because we do not live in a perfect world, errors in the databases are not possible to be
avoided. Very often human errors (as the databases are prepared by the humans) are
discovered, those are syntax errors, wrongly typed digits, etc. Each operator that is using
the PBN equipment needs to establish a database compliance monitoring system. There
needs to be a person within an operator that monitors possible errors. Avaition database
providers are announcing database alerts, whenever an error is discovered.
http://ww1.jeppesen.com/company/alerts/alerts.jsp
Each pilot needs to report a database anomaly to the ATC, whenever error is discovered.
Pilot needs to also conduct a post flight report, as every error needs to be investigated,
whether error occured within AIP, data provider software, or database content, FMS
software etc.
The ARINC424 defines in particular the concept of Path&Terminators (elementary trajectories which
are sequenced in order to represent a complete procedure) which is now more and more adopted
outside the strict A424 community. As an example, the ARINC424 Path&Terminator concept is
reused
in
the
ICAO
Performance-Based
Navigation
Manual.
A key concept in ARINC 424 is that of the “Path-Terminator” – a specific way of defining a leg or
segment of an IFR procedure, based on a set of standard components that define the flight path
along the leg, and the terminator or end-point of the leg.
Different combinations of Path types (eg. a Heading or a Track) and Terminator types (eg. a radio
beacon, RNAV waypoint or DME arc) are used to define 23 different “Path-Terminator” leg types.
These 23 Path-Terminator types are, in effect, the “periodic table” of IFR procedure design and
codification
On FMS, an enroute flight plan consists only of one leg type: the basic “Track (from Fix) to Fix” (TF)
between each of the waypoints entered. When a Departure, Arrival or Approach procedure is
loaded, the flight plan will include each of the path-terminators that make up the procedure.
Note: some FMS/GPS units do not support all the leg types used at the start and end of PBN
procedures, or do not show magenta "overlay".
ARINC 424 - Leg types represenataion on FMS
Standard Instrument Departures (SID), Standard Terminal Arrival Routes (STAR), and
approaches consist of procedural legs that begin and end at prescribed locations or
conditions. A procedural leg has two parts: a leg path and a leg terminator. The path of
these legs can be flown along a heading, a course, a great circle path, or even a constant
arc. The termination of a leg can occur at a specific geographic fix, at a VOR radial crossing,
or when the aircraft attains a certain altitude. The FMS will fly the different procedural leg
types as defined in ARINC 424, of which airport departures and arrivals are comprised.
As each leg type represents different path and terminator, it needs to be appropriately
presented on MCDU (Main Control Display Unit) of FMC (Flight Managment Computer), so
the crew exactly knows what flight path to expect during the flight. Check the link below,
to download a technical training manual for FMS UNS1 - a very popular FMS mounted in
many airliners and corporate jets. The manual describes all 23 PROCEDURAL LEG
TYPES and their representation on MCDU:
http://www.uasc.com/docs/default-source/documents/service-bulletin/3039sv60x-70x.pdf?sfvrsn=2
HEADING TO RADIAL (VR): The aircraft will turn right to a heading of 70° until crossing the PAE 139° radial.
As you can see on
the left, not all of
the leg types are
supported for that
particular EFD:
As there are many versions of the Garmin's EFDs (Electronic Flight Deck), you may expect different
logic of the system based whether you use G1000, G1000Nxi, or G950, G950Nxi etc. If you look on
the hardware of those systems, they look pretty much the same (in terms of external appearance):
Although, the functionality is quite simillar,
there could be some differences between the
different typse of EFDs, ie. G1000 have
instrument representation on EFD, where G950
does not support engine instruments, not to
mention that some of the EFDs have integrated
Automatic Flight Control System (AFCS):
As shown in example below, Garmin G1000 NXI that is used in Tecnam P2010 can
support all ARINC 424 leg types. Always check current AFM and avionics provider
manuals for proper relevant data regarding the system you intend to use.
CA - COURSE TO ALTITUDE
In this missed approach procedure, the altitude immediately following the MAP (in this case ‘6368ft’)
is not part of the published procedure. It is simply a Course to Altitude (CA) leg which guides the
aircraft along the runway centerline until the altitude required to safely make the first turn toward
the MAHP is exceeded. This altitude is provided by Jeppesen, and may be below, equal to, or above
the published minimums for this approach. In this case, if the aircraft altitude is below the specified
altitude (6,368 feet) after crossing the MAP, a direct-to is established to provide a course on runway
heading until an altitude of 6,368 feet is reached. After reaching 6,368 feet, a direct-to is established
to the published MAHP (in this case MOGAL). If the aircraft altitude is above the specified altitude
after crossing the MAP, a direct-to is established to the published fix (MOGAL) to begin the missed
approach procedure.
VA - HEADING TO ALTITUDE
The system adds terminal procedures to the flight plan based on leg types coded within that
procedure in the navigation database. If the terminal procedure in the flight plan contains an identifier
like ‘2000ft’, that indicates a leg that terminates when the specified altitude (2000 feet) has been
exceeded. A heading leg in the flight plan displays ‘HDG’ preceding the DTK (e.g. ‘HDG 008°’). A flight
plan leg requiring the pilot to manually initiate sequencing to the next leg displays ‘MANSEQ’ as the
identifier.
Whenever MANSEQ appears in the flight plan, it means that automatic waypoint sequencing is
suspended. It is announced by ‘SUSP’ annunciation on the HSI and above one of the sofkeys. In all
other phases of the flight 'SUSP' is not shown, but 'OBS' annunciation is displated.
NOTE: VNV is inhibited while automatic waypoint sequencing has been suspended.
Enabling Omni-bearing Selector (OBS) Mode also suspends the automatic sequencing of waypoints in
a GPS flight plan (GPS must be the selected navigation source), but retains the current “active-to”
waypoint as the navigation reference even after passing the waypoint. ‘OBS’ is annunciated to the
lower right of the aircraft symbol when OBS Mode is selected. While OBS Mode is enabled, a course
line is drawn through the “active-to” waypoint on the moving map. If desired, the course to/from the
waypoint can now be adjusted. When OBS Mode is disabled, the GPS flight plan returns to normal
operation with automatic sequencing of waypoints, following the course set in OBS Mode. The flight
path on the moving map retains the modified course line.
OBS is used i.e. to conduct manual (non-published) holding patterns over a given waypoint. With
OBS function ON, any waypoint can act as a vitual VOR.
ARINC 424 - Leg types on GARMIN G1000 / G950 - Holding patterns
As shown on the previous page, Garmin G1000/950 allows for manual conduction of the holding
patterns using OBS funciton.
There is also a possibility of loading the holding pattern for a given published procedure in FMS
flight plan, provided that a given procedure contains a holding pattern on the approach chart.
Garmin EFD, not only will display a holding pattern on the moving map, it will automatically
choose a proper entry method.
Once the 'SUSP' softkey is activated during the execution of the holding patter, the
automatic waypoint sequencing is suspended and the aircraft may stay in the hold until
'SUSP' key is unpressed.
User-Defined Holding Patterns - G950 /
G1000 NXI only!
Instead of using an 'OBS' function for
manual execution of the non-published
holds, the NXI version of Garmin's EFD
allows for creation of a holding patter over
any waypoint from FMS flight plan. Pilot
may define the holding pattern stating the
FIX, inbound coures, left or right turn,
outbound leg, etc.
On the right - Creating a User Defined Holding
Pattern at a Direct To Waypoint (GARMIN NXI
version only):
Fly-by & Fly-over waypoints
• The “fix” in Path-Terminator legs is either based on radio aids or it is a PBN
waypoint. ICAO define a waypoint as “a specified geographical location used to
define a PBN route or the flight path of an aircraft employing PBN”.
• There are 2 kinds of RNAV waypoint: Fly-By and Fly-Over:
FLY-BY:
• A waypoint which requires turn anticipation (start of turn before the waypoint) to allow
tangential interception of the next segment of a route or procedure.
• The aircraft navigation system calculates the start of the turn on to the next route leg before the
way point
• This is the preferred type of waypoint for all Area Navigation (RNAV) Standard Instrument
Departures/Standard Instrument Arrivals (SIDs/STARs)
FLY-OVER:
• A waypoint at which a turn is initiated
• The aircraft starts to turn onto the next route leg as it passes over the waypoint
• Fly-Over waypoints are most often used as the first fix in the missed approach procedure and in
depicting traditional procedures designed around overflying radio aid fixes
Both types of trajectory are subject to variations in wind, aircraft speed and bank angle, navigation system logic and
Pilot or Autopilot performance. However, flight paths resulting from Fly-By turns are, in practice, much more
consistent and predictable, and thus preferred in RNAV procedure design (eg. they require a smaller protected area).
FLY-BY, FLY-OVER PROTECTION AREA
ANS OPS (ICAO Doc. 8168) describes protected area width as:
+/- 2 x RNP + buffer
Buffer is 2nm for arrival, 1nm for initial and intermediate approach and 0.5nm for final, missed
approach and departure.
Fix Tolerance is simply a 1x RNP radius around the waypoint
The Fly-By turn design assumes:
•
•
•
a fix tolerance of RNP-X (eg. 1nm in P-RNAV)
aircraft turn at Rate 1 (3O/sec), up to a maximum bank angle of 25O, whichever is lower
a 5 seconds allowance, from the time the aircraft’s navigation system computes that a turn
should start for either the pilot or autopilot to react and to establish the appropriate bank angle.
The Fly-By turn design thus uses the same bank angles, fix tolerances, wind effects and
pilot/autopilot reaction times as the Fly-Over design. However, the diagrams below illustrate how
much inherently smaller the Fly-By protected area is with those same safety margins built-in.
That is why it is very important with FLY-BY turns not to over-sleep the moment when to start
turning. If you fly using Garmin G1000/G950, it prompts automatically when to start turning when
approaching the turn:
G1000 / G950 top part of the PFD - turn prompt message
En-route, Departure and Arrival specifications:
RNAV10, RNAV5, RNAV2, RNAV1, RNP4, RNP2, RNP1
En-route, Arrival, Departue phases - PBN
There is significant variation in the methods and structures used in instrument procedure
design. The ICAO PBN Manual identifies the following specifications used for En-route,
Arrival and Departure phases (excluding final approach segment): RNAV 10, RNAV 5,
RNP4, RNAV2, RNP2, RNAV 1 and RNP1. There is also A-RNP specification that could be
used in all phases, however we will describe it in the next slides.
OCEANIC:
RNAV 10
RNAV 10 shall be used for oceanic / remote phases of flight. It does not include
requirements for on-board performance monitoring and alerting. even when
operationally approved as “RNP 10”. Direct controller-pilot communications shall be
maintained while applying a distance-based separation minima. Direct controller-pilot
communications shall be voice or CPDLC. The communication criteria necessary for
CPDLC to satisfy the requirement for direct controller-pilot communications shall be
established by an appropriate safety assessment. For RNAV 10 operations, the flight
crew should take account of the RNAV 10 time limit declared for the inertial system, if
applicable, considering also the effect of weather conditions that could affect flight
duration in RNAV 10 airspace. Where an extension to the time limit is permitted, the
flight crew will need to ensure that en route radio facilities are serviceable before
departure, and to apply radio updates in accordance with any AFM limitation.
Separation
minimum
93 km (50NM)
RNP type
Communication
requirement
Surveillance
requirement
Distance verification
requirements
10
Direct controllerpilot
communications
Procedure position
reports
At least every 24
minutes
Accuracy: During operations in airspace or on routes designated as RNP 10, the lateral
total system error must be within ±10 NM for at least 95 per cent of the total flight
time. The along-track error must also be within ±10 NM for at least 95 per cent of the
total flight time.
Separation: 50NM lateral and 50NM longitudinal separation
RNAV 10 is based on INS, IRS FMS or GNSS
RNP4
RNP4 shall be used for oceanic / remote phases of flight. It shall be used with on-board
performance monitoring and alerting function (usually RAIM). For RNP 4, at least two LRNSs
(Long Range Navigation Systems), capable of navigating to RNP 4, and listed in the AFM, may be
operational at the entry point of the RNP 4 airspace. If an item of equipment required for RNP 4
operations is unserviceable, then the flight crew may consider an alternate route or diversion
for repairs. For multi-sensor systems, the AFM may permit entry if one GNSS sensor is lost after
departure, provided one GNSS and one inertial sensor remain available.
For RNP 4 operations with only GNSS sensors, a fault detection and exclusion (FDE) check should
be performed. The maximum allowable time for which FDE capability is projected to be
unavailable on any one event is 25 minutes. If predictions indicate that the maximum allowable
FDE outage will be exceeded, the operation should be rescheduled to a time when FDE is
available.
Accuracy: Lateral TSE must be within ±4 NM for at least 95 per cent of the total flight time.
Separation: 30 NM lateral and 30 NM longitudinal separation.
RNP4 is primarily based on GNSS.
EN-ROUTE / TERMINAL
RNAV5
RNAV 5, also within ECAC almost the same as Basic Area Navigation (B-RNAV), has
been in use In Europe since 1998 and is mandated for aircraft using higher level
airspace. It requires a minimum navigational accuracy of +/- 5nm for 95% of the time
and is not approved for use below MSA.
Without on-board performance monitoring and alerting function.
Lateral TSE must be within ±5 NM for at least 95 per cent of the total flight time.
Route spacing may vary among regional implementations.
Based on VOR/DME, DME/DME, INR, IRS or GNSS.
RNAV5 is used in en-route and arrival phases of the flight.
RNAV2
RNAV 2 supports navigation in en-route continental airspace in the United States. It is
used in En-route continental, arrival and departure phases of flight. Without on-board
performance monitoring and alerting function. Lateral TSE must be within ±2 NM for at
least 95 per cent of the total flight time. Based on DME/DME, DME/DME/IRU and
GNSS.
RNP2
RNP2 could be used in Oceanic, continental, en-route phases of the flight. It can be
used in airspaces considered to be remote. With on-board performance monitoring
and alerting function (usually RAIM). Lateral TSE must be within ±2 NM for at least 95
per cent of the total flight time. It is based on GNSS.
RNAV1
RNAV 1 is almost the same as Precision Area Navigation (P-RNAV). It requires a minimum
navigational accuracy of +/- 1nm for 95% of the time. Qualifying systems must have the
ability to fly accurate tactical offsets; P-RNAV routes must be extracted directly from the
FMS data base and must be flown by linking the R-NAV system to the FMS/autopilot. In
addition, flight crews are restricted from manually adding waypoints to the route. This
level of navigation accuracy can be achieved using DME/DME, VOR/DME or GNSS. It can
also be maintained for short periods using inertial reference systems (IRS) and the length
of time that a particular IRS can be used to maintain P-RNAV accuracy without external
update is determined at the time of equipment certification. It should be noted that if
GNSS is not used as a source then two independent ground-based sources are required to
meet P-RNAV minimum requirements apart from specified short periods of INS ‘backup’,
which is a more stringent requirement than for some older flight management system
(FMS). P-RNAV is used to provide more routes and terminal area procedures and may be
used down to the final approach fix (FAF) on designated approach procedures.
Arrival and departure phases of flight. Without on-board performance monitoring and
alerting function. Lateral TSE must be within ±1 NM for at least 95 per cent of the total
flight time. Based on DME/DME, DME/DME/IRU and GNSS.
RNP1
RNP1 is almost the same like RNAV1, however it is based only on GNSS. It is used with
on-board performance monitoring and alerting function (usually RAIM). It is used for
terminal airspace with no or limited ATS surveillance, with low to medium density
traffic (like EPLL). It is also used for arrival and departure phases of flight.
CONVENTIONAL SIDs & STARs versus PBN
RNP APPROACHES
PBN RNP APCH specification
There are two sub-types of APV:
1. RNP APCH (LNAV/VNAV) - APV
• Lateral navigation: Basic GNSS (as in non-precision approach)
• Vertical guidance: barometric glide path
• Temperature compensated systems, or
• Outside air temperature limitation
• Minimum marked as: ’LNAV/VNAV’
• Accuracy in FAS ±0,3NM / ±75ft
• RAIM required, RAIM prediction required
2. RNP APCH (LPV) - APV, or PA (if approach lights and OCA permits)
• Lateral and vertical navigation with SBAS (in Europe: EGNOS)
• Minimum marked as: ’LPV’
• EGNOS ’channel’ used for procedure identification
• Accuracy in final approach almost like ILS, vertical alarm limit 50m
• Integrity assured with SBAS, RAIM is not needed but SBAS usability check is
required – RAIM FDE is as a backup
NPA RNP APCH:
1. RNP APCH (LNAV) - NPA
• Lateral navigation: Basic GNSS
• Accuracy in final approach segment ±0,3NM
• RAIM required, RAIM prediction required
2. RNP APCH (LP) - NPA
• Lateral navigation: GNSS with SBAS
• Accuracy in final approach segment ±0,3NM
• Integrity assured with SBAS.
LNAV/VNAV:
The scaling of the needles is usually linear, however ie. Garmin shows scaling of
LNAV/VNAV using angular deviations.
LPV:
LPV Final Approach Segment is specially coded into a Data Block inside the on-board navigation
database. It is known as the FAS DB. It ensures angular lateral and vertical guidance based on GNSS
augmented by SBAS.
FAS DB
• “The set of parameters to identify a single precision
approach or APV and define its associated approach
path” (ICAO)”
• Is part of the data package of an APV SBAS procedure:
• The FAS-DB contain the parameters that define the Final
Approach Segment geometry
Approach parameters in FAS data block:
• Operation Type ( i.e APV )
• FPAP ( Flight Path Alignment Point)
• LTP ( Lat/ Lon WGS84)
• LTP ellipsoidal height
• GP Angle (VPA)
• GP course width
• HAL (Horizontal Alert Limit)
• VAL (Vertical Alert Limit)
• Others
FAS data block is protected with a CRC (cyclic redundancy check) parameter, which
is verified by the receiver.
RNP APPROACHES - COMPARISON
SCALING
In LNAV/VNAV the vertical scaling is usually linear all the way to the ground instead of
being angular like on an ILS glideslope. This means that as the airplane approaches
the runway the vertical scaling remains the same. However, G1000 scaling is different.
GARMIN G1000 / G950 GP vertical scaling - LPV & LNAV/VNAV
LPV & LNAV/VNAV vertical guidance scalining on G1000 - not linear
• FSD = Full Scale Deflection
• G1000 annunciation LPV: ’LPV’
• G1000 annunciation LNAV/VNAV: ’L/VNAV’
• Guidance needle and GP diamond in magenta color
• Tecnam P2006T is not apporved for LNAV/VNAV. However, there is LNAV+V approach possible!
LNAV+V is not LNAV/VNAV!
LNAV+V uses SBAS to provide guidance, however vertical guidance is
advisory only. For LNAV+V, LNAV minimums shall be used!
GARMIN G1000 / G950 horizontal scaling
GARMIN G1000 / G950 horizontal scaling – final segment
GARMIN G1000 / G950 horizontal scaling – final segment
T-BAR and Y-BAR arrangements
So far we were describing RNP approaches in their Final Approach Segment (FAS). Now,
let's concentrate on Initial and Intermediate Approach Segment.
Most RNP Approaches final approach procedures leading to LNAV, LP, LNAV/VNAV or
LPV minima, may be preceded by either an initial and intermediate T-bar or Y-bar
approach. In this case all segments are published on the same chart.
A T-BAR or Y-BAR arrangement permits direct entry to the procedure from any
direction, provided entry is made from within the capture region associated with an
IAF.
Where one or both offset IAFs are not provided, a direct entry will not be available from all
directions. In such cases a holding pattern may be provided at the IAF to enable entry to the
procedure via a procedure turn.
Sometimes may be preceded by an initial and intermediate RNAV 1 approach (generally preceded
by a RNAV 1 STAR) or by radar guidance.
Y-Bar is used when 90-deg arrangement (T-Bar) is not practicable. (However, turn at IF is Max 70
deg ).
Effective when airspace is sufficient. However, maybe ineffective for mountainous area (MSA,
altitude restriction for obstacle, etc.).
Following turns are assumed, in principle:
For T-bar - within 90 deg for turns at IAF / IF
For Y-bar: - Within 70 deg for turns at IAF (center) and 70-110 deg for turns at IAF (R/L).
Optimum distance IAF-IF 5 NM (so its worth to be at 210 knots or below at IAF), minimum distance
IF - FAF/FAP 2 NM.
PBN Operations - operating procedures
• Approach must be selected in its entirety (not built-up by the pilot in the FMS)!
• Either the approach is stored in the system, or to be considered NON-EXISTANT: a
“home-built” procedures MAY NOT BE FLOWN!
• First the approach must be LOADED, then only may a DCT (Direct to) be selected!
• Vectors may be accepted to (any of the IAF)
• Vectors may be accepted to IF, IF THE COURSE CHANGE DOES NOT EXCEED 45°
• Vectors directly to the FAF MAY NOT BE ACCEPTED!
The terminal arrival altitude (TAA) is the lowest altitude that will provide a minimum
clearance of 300 m (1 000 ft) above all objects located in an arc of a circle defined by
a 46 km (25 NM) radius centered on the initial approach fix (IAF), or where there is no
IAF on the intermediate approach fix (IF), delimited by straight lines joining the
extremity of the arc to the IF. The combined TAAs associated with an approach
procedure shall account for an area of 360 degrees around the IF. (ICAO Doc 8168
PANS-OPS).
It's concept is similar to MSA on other cards.
Terminal Arrival Altitude (TAA) is established in combination with T/Y Bar. TAA is
published for smooth descent and entry to the approach and also for the use in
emergency. It is used as flight altitude until IAF (or IF) of T/Y Bar.
Area:
Centered on IAF(or IF)
• Radius = 25NM + Buffer Area(5NM)
• Obstacle Clearance(MOC) = 1,000ft
• Sectorized by the line connecting IF-IAF.
RNP AR APPROACHES
RNP (AR) APCH, AR - (Authorization Required)
RNP AR - Authorization Required approaches. They are depicted on the charts as
RNAV(RNP). They require special certification procedure:
Procedure needs to be certified and published as RNP AR by the state where the
aerodrome is located;
• Operator needs to be approved to conduct a given RNP AR procedure for a given
aerodorme and runway!
• Aeroplane needs to be approved for RNP AR
• Pilots need to be approved for RNP AR and trained. RNP AR requires pilot recurrent
trainings every year for a given aerodorme/runway combination!
Compared to standard RNP approach procedures, the RNP AR approach procedures are
characterized by:
• RNP values ≤ 0.3 NM and/or
• Curved flight path before and after the Final Approach Fix (FAF/FAP) or Final Approach
Point.
• Protections areas laterally limited to 2xRNP value without any additional buffer.
ADVANCED RNP
Advanced RNP
PBN evolution is set to continue with the introduction of other navigation specifications like
Advanced RNP. A-RNP applications are being developed at the moment.
Advanced RNP will become the next ECAC-wide navigation specification used in enroute and
terminal airspace, including the approach, missed approach and departure phases of flights.
A-RNP airspace requirements:
Lateral navigation
• Closer route spacing, particularly in the en-route;
• Maintaining same spacing between routes on straight and turning segments without a need to
increase route spacing on the turn*;
• Reduction of the size of the holding area to permit holds to be placed closer together or in more
optimum locations;
• Aircraft ability to comply with tactical parallel offset instructions as an alternative to radar
vectoring;
• Means of enabling curved approaches, particularly through terrain rich areas but also to support
environmental mitigation.*
* Note: Repeatable and predictable turn performance is the basic operational requirement.
Longitudinal navigation
• Some means to enable the metering of traffic from en-route into terminal airspace;
•
Vertical navigation
Effective management of vertical windows to segregate arrival and departure flows (example in
diagram) h. Effective use of CDOs and CCOs (again for environmental mitigation);
CDO - Continuous Descent Operations
CCO - Continuous Climb Operations
The requirements of A-RNP serve various benefits via. capacity, flight and ATM system efficiency,
airport access, enhanced system and sequencing predictability, etc.
The above airspace requirements were extensively analysed and debated with
respect to cost, avionics compatibility and feasibility by navigation experts in
European and International fora. (Note that the introduction of the PBN Concept
meant that European requirements had to dove-tail into an international context
because the PBN concept is anchored in international harmonisation of
navigation specifications). Included in these analytical exercises were airspace
users such as General Aviation, Military aviation, air transport aviation and
organisations such as IATA.
One of the biggest challenges in writing the Advanced RNP specification was how
to ensure its flexible application particularly in the terminal environment. For this
reason, early drafts of the Advanced RNP specification proposed the flexibility to
choose one of a series of accuracy values in each flight phase; this capability is
called “Scalable RNP”. Nevertheless, subsequent analysis of both European and US
fleets demonstrated that ‘scalability’ was too ambitious to be included as a
requirement in the Advanced RNP specification. As such, the specification has now
been published with ‘conservative’ default lateral accuracy values in all flight
phases but scalable RNP remains an optional function in Advanced RNP. The idea
is to have Advanced RNP with this option as a candidate replacement for RNP AR
APCH in those cases where terrain challenges are not significant (RNP AR APCH is
the only other specification including scalability, but it requires ‘special
authorisation’ because of its rigorous requirements, and is therefore costly).
Of particular interest to airspace planners is the closer route spacing that can be
enabled with Advanced RNP on both straight and turning segments (the latter due to
the RF/FRT requirements). In the table below, the interpreted results of various
EUROCONTROL route spacing studies are shown. The route spacing advantages of
Advanced RNP are contrasted to those of P-RNAV and B-RNAV.
One of the main benefits provided by Advanced RNP is the potential it has to increase
flight efficiency and overall efficiency of the ATM system. Increased flight efficiency
stems from the great flexibility of being able to place ATS Routes, SIDS and STARS in the
most convenient place. The predictable turn performance inherent in Advanced RNP
through the RF in terminal operations and by associating FRT en-route, also makes it
possible - due to enhanced track keeping in the turn - to place routes where they cannot
necessarily be placed today with RNAV 1 or RNAV 5. This has a two fold benefit: the ATM
system can benefit in terms of efficiency by a route capable of being placed in a more
optimum place; aircraft efficiency is enhanced by the route capable of being placed
where it better suits the aircraft performance, and the predictable turn and track
keeping performance inherent in Advanced RNP through RF and RNP mean that the
noise footprints are reduced.
To provide the benefits, Advanced RNP needs to be used ECAC-wide in the upper
airspace. A mix and match of P-RNAV / B-RNAV / Advanced RNP will not provide the
benefits that Advanced RNP alone can deliver. This is because it becomes labour
intensive for ATC to manage the mix of aircraft navigation performance. Moreover,
additional routes would need to be created for differently qualified aircraft; this will
result in airspace capacity limitations and additional controller workload (and can also
result in airborne navigation databases starting to run out of space).
RNP 0.3 HELICOPTERS
RNP 03 (HELICOPTERS)
The PBN specification of RNP 0.3 was developed specifically for helicopters, to enable
them to obtain maximum benefit from implementation of PBN. As shown on the
previous page, it is required for RNP 0.3 (H) that Operator is approved to conduct such
operations. Just Like with RNP AR Apch. the Operator needs to provide proper crew
training, helicopters need to be properly equipped.
The specification is designed for use on all phases of flight, including continental en-route
operations, terminal area (arrival, departure and initial/intermediate segments of approach) and
servicing of offshore rigs.
The benefits from allowing helicopters to operate to this specification include reduced separation
from other traffic to allow simultaneous operations in dense terminal airspace, low level operations
where multiple obstacles exist and more efficient noise sensitive routings. Another advantage of
RNP 0.3 (H) is the ability to use it in rough mountainous areas.
Main keypoints of RNP 0.3 (H):
• GNSS only
• RAIM or SBAS
• LPV, or LNAV
RNP 0.3 is predicated on the use of GNSS as the navigation sensor. The GNSS receiver must include
augmentation either by RAIM or SBAS. Where augmentation is provided by RAIM, a prediction
service is also required to ensure RAIM coverage for the intended operation. This may be
accomplished using onboard equipment or by use of the NOTAM facility or a RAIM prediction tool. A
predicted loss of RAIM of more than 5 minutes will require a change to the plan (delayed departure
or alternate routing). In the case of a short term loss it MAY be permissible to continue with RNP 0.3
operations.
Like for airplanes, where SBAS augmentation is used there is no requirement for RAIM prediction
services, provided the operation is entirely within the coverage of the SBAS service.
First Helicopter LPV approach with RNP 0.3 transitions approved in Norway
On January 2017, the Civil Aviation Authority of Norway has approved new Helicopter Instrument
approach and departure procedures for serving Trondheim Hospital. The procedures have been
designed and validated by PildoLabs (recently UK approved procedure design organisation) and
Norsk Luftambulanse. They are based on GPS and EGNOS and allow a safer operation in low visibility
conditions. As a result, a more continuous medical transportation service can be offered.
Norsk Lufthambulanse recently obtained the operational approval required to fly these procedures
(RNP 0.3), being the first European helicopter operator in obtaining such recognition.
PinS Operations - Helicopters
A Point in Space (PinS) is part of RNP 0.3 (H) helicopter operation, which consists of an
instrument segment and visual segment.
PinS procedures are used for transitions from visual to instrument flight and from
instrument to visual phase, they consist of:
• Departures - SIDs,
• Approaches
PinS Departures
The departure consists of a visual and an instrument segment. The pilot will maneuver
visually from the departure site to the initial fix of the instrument segment (IDF). On
reaching the IDF the pilot transitions from visual to instrument flight to join the PBN
departure route. Details of the PBN specification used for this segment will be shown on
the chart.
If it states on the plate:
• "Proceed Visually" - Obstacle identification provided
• "Proceed VFR" - Pilot responsible to 'see and avoid
Proceed Visually implies the pilot is able to navigate visually, but in conditions which
may not meet the State requirement for VFR flight. 'Proceed Visually' implies that
obstacle identification in the departure area has been performed, whereas for a
'Proceed VFR' the pilot is solely responsible to see and avoid obstacles.
PinS Approaches
The instrument segment is based on the RNP APCH specification and is designed to take
the helicopter to defined point in space, at which point (assuming the required visual
references have been acquired) the helicopter will then navigate visually to the landing
site. The instrument approach segment can be published using either LNAV or LPV
minima.
Just like with PinS departures - the visual segment following this is described as either
'Proceed Visually' or 'Proceed VFR’.
Proceed Visually implies the pilot is able to navigate visually, but in conditions which may
not meet the State requirement for VFR flight. For PinS approaches including a Proceed
Visual instruction, the visual segment may be defined as either "Direct" or
"Maneuvering".
• Direct Visual Segment - Obstacle identification for straight in (+/- 30deg) landing from
Mapt to landing site, Descent Point is defined,
• Maneuvering Visual Segment - Obstacle identification for landing from a direction
other than directly from Mapt,
• Passing the Mapt transition to VFR (State rules apply) - Pilot responsible to see and
avoid Obstacles.
Wrong names - WATCH OUT!
Thank you