RVSM
(Reduced Vertical Separation Minima)
Capt. Thammarat Thammalikhit
Outline
• General
• Operation Procedures
• Contingency Procedures
General
Introduction
• RVSM airspace is defined as any airspace or route where the aircraft are
separated vertically by 1000 ft between FL290 and FL410 inclusive
(instead of 2000 ft).
• The objective of RVSM is to increase the route capacity of saturated
airspace while keeping at least the same level of safety. This can be
achieved by imposing stringent requirements on equipment and training of
personnel, flight crews and ATC controllers. As part of the RVSM program,
the altitude keeping performance of the aircraft is monitored to verify that
airspace users are applying the approved criteria effectively and that the
overall safety objectives are being maintained.
General
RVSM Benefits
Under the RVSM implementation program the following benefits are accruing:
• Improved operations/efficiency
•Greater availability of the more fuel-efficient altitudes
•Greater availability of the most fuel-efficient tracks or routes
•Increased probability that an operator will be cleared onto the desired
•track or altitude
•Enhanced controller flexibility to manage traffic through an increased
•number of available altitudes
General
Background
North Atlantic (NAT) RVSM implementation
RVSM was first implemented in NAT on March 27, 1997.
Phase I of North Atlantic (NAT) RVSM was implemented from FL 330 to FL 370,
inclusive, within Minimum Navigation Performance Specifications (MNPS) airspace.
Phase II of NAT RVSM expanded the MNPS airspace from FL 310 to FL 390, inclusive,
on October 8, 1998. All aircraft that had not been approved for RVSM operations were
excluded from this airspace. Ongoing system performance monitoring and review of
aircraft approvals continued during Phase II of NAT RVSM implementation.
Phase III of the NAT RVSM, which led to full implementation, expanded the NAT MNPS
airspace from FL 290 to FL 410. The Phase III implementation was concurrent with the
implementation of RVSM in Europe on 24th January 2002.
General
PACIFIC RVSM Operational Implementation Plan
RVSM was implemented in Pacific Oceanic airspace between
FL290 and FL390 (inclusive) on February 2000. ICAO RVSM
Implementation Task Force had agreed on the operational plan
for the implementation of RVSM in the Western Pacific/South
China Sea area, in conjunction with the revised ATS route
structure for the South China Sea. The meeting agreed that
RVSM could be applied between FL290 and FL410 on the
revised route structure, using the single alternate flight level
orientation scheme for the assignment of RVSM levels. The
meeting also agreed that only RVSM-approved aircraft should
be permitted to flight plan at the RVSM levels, to avoid a mixed
environment of operations.
General
RVSM Approval Overview
Prior to the granting of an RVSM approval the aircraft must satisfy the
following requirements:
1. the aircraft must be eligible for RVSM (i.e. must satisfy the vertical
navigation performance)
2. the instituted appropriate procedures in respect of continued
airworthiness (maintenance and repair) practices and programs.
3. the instituted appropriate flight crew procedures and training for
operations in RVSM airspace.
4. the instituted RVSM monitoring programs.
5. The RVSM approval process consists of two discrete approvals, an
airworthiness approval and an operational approval.
General
Height Monitoring Systems
There are 3 independent height monitoring systems currently in use. These are:
1.GPS Monitoring Unit (GMU). This is a portable carry on device used to
estimate the ASE of a single flight for one aircraft. The advantage is that the
aircraft can be monitored almost anywhere
2. Height Monitoring Unit (HMU). An HMU is a fixed ground based system
which with one central and four outer receiving stations.
3. ADS-B Height Monitoring Systems (AHMS). An Automatic dependent
surveillance broadcast (ADS-B) Height Monitoring System (AHMS) is a height
monitoring system that utilizes data from an existing ADS-B network.
General
It is important to ensure that the monitoring data is correlated to the
correct aircraft. Height monitoring systems only receive the aircraft
ICAO 24-bit aircraft identifier. It is necessary to compare the 24- bit
aircraft address to the address provided by the State in the RVSM
approval data.
All operators of RVSM approved aircraft are required to participate in
the RVSM height monitoring programme. The principle purposes of
the long term height monitoring programme are to verify long term
ASE stability and the efficacy of an operator’s continued airworthiness
programme
Operation Procedures
Flight planning
During flight planning, the flight crew and dispatchers, if applicable, should pay particular
attention to conditions which may affect operation in RVSM airspace.
These include, but may not be limited to :
(a) verifying that the aircraft is approved for RVSM operations
(b) block 10 (equipment) of the ICAO flight plan should be annotated with the
letter “W” for filing in RVSM airspace.
(c) reported and forecast weather conditions on the route of flight
(d) minimum equipment requirements pertaining to height-keeping systems
(e) Traffic Alert and Collision Avoidance System (TCAS) equipage. TCAS equipage
requirements are contained in each AIP or regional supplementary procedures.
(f) if required for the specific aircraft group; accounting for any aircraft operating
restrictions related to RVSM airworthiness approval.
Operation Procedures
Pre-flight procedures
Accomplish the following actions during pre-flight.
(a) Review aircraft logs and forms to ascertain the condition of equipment required for in the RVSM airspace.
(b) The external inspection of aircraft, pay particular attention to the condition of static sources, the condition
of the fuselage skin near each static source or the other component affecting altimetry system accuracy.
(c) Before takeoff:
• The aircraft altimeters should be set to the altimeter setting (QNH) and should display a field elevation
The difference between the field elevation and the display on the altimeters should not exceed 75 ft.
• The 2 primary altimeters should also agree within limits specified by the Airplane Flight Manual (AFM),
(d) Equipment required for flight in RVSM airspace should be operational, and indications of malfunction
should be resolved.
Operation Procedures
Procedures before RVSM airspace entry
The following equipment should be operating normally at entry into RVSM airspace otherwise request a new
clearance so as to avoid flight in RVSM airspace. :
(a) 2 altitude measurement systems, as defined by the RVSM
(b) Automatic altitude-keeping device(s);
Note.— Redundancy requirements for altitude-keeping devices should be established by regional
agreement after an evaluation of such criteria as mean time between failures, length of flight
segments and availability of direct pilot controller communications and radar surveillance.
(c) at least 1 altitude-reporting transponder (For ACAS system according to annex 10 Vol. IV)
; and
(d) one altitude-alerting device;
Operation Procedures
In-flight procedures
Generally, flight crew operating procedures in RVSM airspace are no different from those in any other airspace;
however, the continuity of RVSM operations will require periodic review of procedures specific to a region,
e.g. contingency procedures
crews should be reminded to minimize the deviations from the cleared flight level.
and should be reminded of the importance of adhering to the following in-flight procedures:
(a) In level cruise, except in contingency or emergency situations, the aircraft should not intentionally
depart from CFL without a positive clearance from ATC.
(b) During cleared transition between levels, the aircraft shall not be allowed to overshoot or undershoot
the CFL by more than 150 ft (45 m).
Note : It is recommended that the level off be accomplished using the altitude capture feature of the
automatic altitude-control system, if installed.
High rates of climb or descent may result in nuisance TCAS alerts on older TCAS equipment
(TCAS 7.0) when in vicinity of other traffic or in areas of high traffic density. For this reason it
may be advisable to reduce the rate of climb/descent to less than 1,000 ft/min within 1,000 ft of
the cleared flight level.
Operation Procedures
In-flight procedures
(c) An automatic altitude-control system should be operative and engaged during level cruise,
adherence
to cruise altitude should be done by reference to one of the two primary altimeters.
(d) The altitude-alerting system should be operational.
(e) At intervals of approximately 1 hour, make cross-checks between the primary altimeters and the
stand-by altimeter. A minimum of two primary altimeters should agree within 200 ft (60 m).
(Otherwise ,notified to ATC).
Note the difference between the primary and stand-by altimeters for use in contingency situations.
(h) Crew should ensure the autopilot used and the transponder selected use the same air data source
for altitude information.
Operation Procedures
Operation Procedures
Equipment failures
ATC shall be informed as soon as practicable of the following equipment failures :
(a) failure of all automatic altitude-keeping devices on board the aircraft;
(b) loss of redundancy of altimetry systems, or any part of these, on board the aircraft;
(c) failure of all altitude-reporting transponders;
(d) loss of thrust on an engine necessitating descent; and
(e) any other equipment failure affecting the ability to maintain CFL;
Operation Procedures
Post flight
In making maintenance logbook entries against malfunctions in height-keeping systems,
The pilot should detail the actual defect and the crew action taken to try to isolate and rectify the fault.
Note the following information when appropriate:
(a) primary and standby altimeter readings.
(b) altitude selector setting.
(c) subscale setting on altimeter.
(d) autopilot used to control the airplane and any differences when the alternate system was selected.
(e) differences in altimeter readings if alternate static ports selected.
(f) use of air data computer selector for fault diagnosis procedure.
(g) transponder selected to provide altitude information to ATC and any difference if alternate transponder or
altitude source is manually selected.
Contingency Procedures
Weather deviation procedures
The following procedures are intended for deviations around adverse meteorological
conditions.
When the pilot initiates communications with ATC, a rapid response may be obtained
by stating "WEATHER DEVIATION REQUIRED" to indicate that priority is desired on
the frequency for ATC response.
When necessary, the pilot should initiate the communications using the urgency call
"PAN PAN" (preferably spoken three times). The pilot shall inform ATC when weather
deviation is no longer required, or when a weather deviation has been completed and
the ACFT has returned to its cleared route.
Contingency Procedures
Weather deviation procedures
Contingency Procedures
Contingency
Procedures
Contingency Procedures
Contingency
Procedures