CFIT
Controlled Flight Into Terrain; describes an accident in which an
aircraft under pilot control is unintentionally flown into the ground, mountain,
water or an obstacle. Main causes for CFIT accidents are fatigue, loss of SA,
disorientation, misinterpreting charts or ATC clearances. To reduce the risk
of CFIT, using GPWS and obeying the ICAO rules are important.
As an example; Atlasjet Flight 4203 can be mentioned I think. In November
2007 it crashed during its approach to Isparta. The authorities declared that the
accident was caused by pilot error as a result of the condition known as spatial
disorientation. In addition, GPWS was not working properly.
SITUATIONAL AWARENESS
SA is basicly knowing the position and what is happening around. Monitoring
radio communication, weather discussion and applying CRM can enhance SA by
helping the pilot to develop a mental picture of what is happening around.
ORIENTATION PROBLEMS
In VFR conditions, you obtain your orientation mainly through your vision. On
the other hand in IFR conditions or at night your body relies upon your vestibular and
kinesthetic sense. Since these senses are unreliable, disorientation may occur.
Fatigue, anxiety, workload, alcohol, drugs increase the risk of disorientation.
There are two types of disorientation; spatial and vestibular.
Spatial disorientation occurs when there is a conflict between central vision and
peripheral vision. For example; one feels himself moving as the vehicle next to him is
moving while he is in a stationary vehicle.
As an example; Atlasjet Flight 4203 can be mentioned I think. In November
2007 it crashed during its approach to Isparta. The authorities declared that the
accident was caused by pilot error as a result of the condition known as spatial
disorientation.( The pilot is believed to have lost the sight of line for the horizon and
instead of trusting the flight instruments, diverted the aircraft to the route where the
crash occurred .)
Vestibular disorientation is caused by misleading signals sent from vestibular
system in inner ear to brain. For example, in a prolonged constant rate of turn, you
will not sense the bank after a while and if you level the aircraft you will sense as if
you bank the opposite side. (A rapid acceleration during takeoff can create the
illusion of being a nose-up attitude and abrupt change from climb to straight and level
flight can create the illusion of tumbling backwards.)
(Kinesthetic sense is the term used to describe the awareness of position obtained
from nerves, joints and muscles. This sense is unreliable because the brain can not tell
the difference between gravity inputs and g-load inputs.)
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GPWS (also known as TAWS [Terrain Access Warning System] by FAA)
Ground Proximity Warning System is a system designed to alert pilot, if aircraft is
in danger of flying into the ground or an obstacle. To warn pilot about the closure of
impact, this system combines some data which are: R/A, barometric altitude,
configuration, vertical speed, present position, gear, flap and throttle positions, glide
slope deviation, approach minima, and in Enhanced mode DTED, In EGPWS wind
shear is also shown. EGPWS reduces the risk of CFIT almost 50 times. Since 2005,
GPWS is mandatory on public transportation aircrafts with a maximum take-off mass
(MTOM) of over 5700 kg.
Atlasjet Flight 4203 is a proper example I think, to prove the importance of
GPWS. In November 2007, it crashed during its approach to Isparta. One of the
reasons to this accident was that GPWS was not working properly.
(DTED: Digital Terrain Elavation Data)
TCAS(Traffic alert and Collision Avoidance Sys)–ACAS(Airborne Collision Avoid.Sys)
TCAS is a specific type of ACAS concept.
TCAS is an aircraft system based on transponder signals, which operates
independently of ground-based equipment. TCAS provides advice to the pilot
on potential conflicting aircraft that are equipped with SSR transponders.
It is mandated by ICAO to be fitted to all aircraft with a maximum take-off
mass (MTOM) of over 5700 kg or authorized to carry more than 19
passengers.
There are 4 types of TCAS;
TCAS 1 provides only TA up to a range of about 40 miles.
TCAS 2 provides TA and RA for only vertical separation.
TCAS 3 provides TA and RA for both vertical and horizontal separation.
TCAS 4 provides TA and RA for both vertical and horizontal separation.
And also uses additional position information encoded by the target aircraft
through an air-to-air data link to generate the bearing information. (So the
accuracy of the directional antenna would not be a factor.)
TA - Traffic Advisory
(Traffic Information)
RA - Resolution Advisory (Maneuver Advice)
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CRM
Crew Resource Management is the effective use of all available resources
such as equipment, procedures and people. Applying CRM, promotes safety and
improves the efficiency of operations.
CRM is used primarily for improving air safety and mainly focuses on some
cognitive and interpersonal skills. In this context, cognitive skills are defined as the
mental processes used for gaining and maintaining situational awareness, for solving
problems and for taking decisions. Interpersonal skills are regarded as
communications and a range of behavioural activities associated with teamwork.
These are often difficult skills to master, as they may require significant changes in
personal habits, interpersonal dynamics, and organizational culture.
Importance of CRM first appeared in 1978 with the crash of United Airlines
Flight 173. The plane ran out of fuel while the flight crew were troubleshooting a
landing gear problem. As a result of this accident United Airlines was the first airline
to provide CRM training for its cockpit crews in 1981.
Basicly there are 5 steps in CRM process in cockpit;
Address the individual - "Hey Chief," or "Captain Smith," or "Bob,"
State your concern-"I'm concerned that we may not have enough fuel to fly around this storm system"
State the problem as you see it - "We're only showing 40 minutes of fuel left,"
State a solution - "Let's divert to another airport and refuel,"
Obtain agreement - "Does that sound good to you, Captain?"
UNITED AIRLINES FLIGHT 173
United Airlines Flight 173 crew was making an approach to the Portland Airport on
the evening of Dec 28, 1978 when they experienced a landing gear abnormality. The
captain decided to enter a holding pattern so they could troubleshoot the problem. The
captain focused on the landing gear problem for an hour, ignoring repeated hints from the
first officer and the flight engineer about their decreasing fuel supply. He realized their
horrible situation only when the engines began flaming out. They crash landed in a
wooded area, over six miles short of the runway without injuring a single person on the
ground. Of the 189 people onboard, 8 passengers and 2 crewmembers died in the
accident.
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DUTCH ROLL
If the aircraft is yawed to the right, the left wing advances (sideslip) and
generates more lift, while the right wing slows down and produces less lift. The result
of this imbalance in lift is rolling in the direction of the initial yaw. The advancing wing
also produces greater drag due to the larger areas exposed to the airflow, which
causes the aircraft yaw in the opposite direction. This results in the right wing
producing more lift than the left wing, reversing the direction of the roll. The final
result is rolling and yawing oscillation which have the same frequency.
Dutch Roll is mainly caused by relatively weaker positive directional stability
than positive lateral stability. Sweepback and dihedral wings have more tendencies
to Dutch Roll. Yaw dampers prevent Dutch Roll on swept-wing aircrafts.
To recover from a Dutch Roll motion, you shoud apply a sharp aileron input
towards the upcoming wing. It’s not advised to use rudder to correct Dutch Roll,
the roll is much more visible than the yaw, so easier to correct.
ADVERSE YAW
Since the downward deflected aileron produces more lift or in other saying
outside wing produces more lift and induced drag, the same wing slows down
slightly. This creates opposite side yawing motion. This is called adverse yaw.
This is more common at lower airspeeds. Application of rudder is used to
correct adverse yaw. As a result, all the turns should be coordinated turns.
AERODYNAMIC FLUTTER
Flutter is an unstable oscillation of fixed or movable surfaces of an aircraft;
such as wings, stabilizer, ailerons or elevator. Flutter can damage these surfaces.
Manufacturers should design aircrafts in such a way that they will not suffer
from flutter below VNE or below VMO/MMO (Max Operating Velocity or Mach number).
HOLDING ENTRY PROCEDURES
DIRECT ENTRY: Directly proceed to the fix, and then, after crossing the fix,
simply turn to the outbound heading. While passing “abeam” position, start your timer
and fly for one minute. Then, turn to intercept the inbound track.
PARALLEL ENTRY: After crossing the fix, simply turn to the outbound heading
and maintain that heading for one minute, then make a 180° turn into the holding area
and proceed directly to the fix. After crossing the fix, turn to the outbound heading.
OFFSET OR TEARDROP ENTRY: After crossing the fix, turn into the
protected area (Standart: Outbound-30º, Non-standart: Outbound+30º), and fly for one
minute, and then turn back to inbound, proceed to the fix and continue from there.
4
HOLDING PROCEDURES
Holding procedures are mainly used to provide separation between traffics. There
are two types of holding; Standard and nonstandard. In standart holding right hand
turns, in non standard holding left hand turns are made. If it’s not instructed or
published, standard holding is performed. Each circuit of holding begins and ends at a
certain fix. These fixes may be navaid, intersection or a certain DME distance.
Inbound leg of holding is always towards the fix.
There are two ways of holding procedure; first one is done by timing and the
second one is done by leg length. In timing procedure inbound leg is flown one
minute at or below 14000 feet and above 14000 feet one and a half minutes. If holding
is to be performed by leg length, no timing is required.
If holding speed is not published on the chart, ICAO standards are used;
•
•
•
•
Up to 14000 ft
14000 ft to 20000 ft
20000 ft to 34000 ft
Above 34000 ft
: max 230kts
: max 240kts
: max 265kts
: max M0.83
There are three methods used to enter a holding pattern. Parallel, direct
and teardrop entry. The entry procedure depends on your heading and inbound course
of the holding pattern.
TOP OF DESCENT / BOTTOM OF DESCENT
Top of descent is a point that an aircraft starts its descent to reach a point in
a designated altitude with a specific vertical speed or descent angle.
Bottom of descent point is the end point of the descent, as calculated by
FMS or RNAV.
PROCEDURE TURN- BASE TURN-RACETRACK
Procedure turn is used for reversing course and descending to a certain
altitude. By means of procedure turn, aircraft is established inbound to final
approach. There are two types of procedure turns: 45-180 and 80-260
degrees.
Base Turn is made by first of all proceeding outbound on a certain
track/bearing from a fix for a set time or distance (depending on the category
of the airplane) and then by making a turn in order to position the aircraft on a
final approach track/course.
Racetrack procedure is made by firstly turning from the inbound track through
180º on to the outbound track, for 1, 2 or 3 minutes, followed by a 180º turn in
the same direction to return to the inbound track.
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STABILIZED APPROACH
A stabilized approach is the safest profile, and it is one of the most
critical elements of a safe approach and landing operation. There are five
basic elements for a stabilized approach:
1) The airplane should be in the landing configuration early in the
approach.
2) The airplane should be stabilized on profile before descending
through 1000 feet.
3) The optimum descent rate should be 500-700 fpm.
4) Indicated airspeed should be not more than VREF + 5 and never less
than VREF.
5) The engine speed should be at a setting that allows best response
when if a rapid power increase is needed or a go-around should be
considered by the pilot.
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STRAIGHT IN LANDING and STRAIGHT-IN APPROACH
Straight-In Approach is an instrument approach in which final approach
is begun without a procedure turn or holding. Straight-in approach is not
related with the landing procedure. A straight-in approach can be followed by
a circle to land or straight in landing.
Straight-In Landing is a landing made on a runway aligned within 30°
of the final approach course. Any circle to land is not a straight-in landing.
.
PRECISION AND NON-PRECISION APPROACH
Precision approach, as it is understood from its name, is more precise and
has lower minimums than non-precision approach. The easiest way to
distinguish precision and non-precision approach is to look up chart's minima
part. If DA(H) is published it is a precision approach. If MDA(H) is
published, it is a non-precision approach.
The types of precision approach are ILS, MLS, PAR and WAAS GPS RNAV.
The types of non-precision approach are NDB, VOR, LOC and GPS RNAV.
(WAAS= Wide Area Augmentation System)
Final approach segment for a precision approach begins with
intercepting the glide slope at designated altitude.
On the other hand, final approach segment for a non-precision
approach begins at designated FAF. When FAF is not designated, final
approach begins at final approach point (FAP) where procedure turn
intercepts the final approach course inbound.
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ILS CATEGORIES
CategoryI ILS has minimums of 200ft DH and 800m visibility or 550mRVR.
Category II ILS has minimums of 100-200 ft DH and 350 m RVR.
Category III has three sub-categories.
III A ILS has minimums of below 100 ft DH and 200 m RVR.
III B ILS has minimums of below 50 ft DH and 50-200 m RVR.
III C ILS has no minimums.
EQUIPMENT
CAT-1 AIRCRAFT: The plane has to be equipped apart from the devices for
flying in IFR (Instrument Flight Rules) conditions also with the ILS system and a
marker beacon receiver.
CAT-2 AIRCRAFT: The plane has to be equipped with a radio altimeter or
an inner marker receiver, an autopilot link, a raindrops remover and also a
system for the automatic draught control of the engine can be required. The crew
consists of two pilots.
CAT-3 A AIRCRAFT: The aircraft has to be equipped with an autopilot with
a passive malfunction monitor or a HUD (Head-up display).
CAT-3 B AIRCRAFT: A device for alteration of a rolling speed to travel speed.
BASIC SYSTEMS FOR ILS: VHF localizer transmitter, UHF glide slope
transmitter, marker beacons, approach lighting system
(If there is a predominance of either 90 Hz or 150 Hz modulation, the
aircraft is off the centerline.)
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BACK COURSE
This type of approach typically is found at smaller airports that do not have
ILS approaches on both ends of the runway, where often the older localizer antennas
are less directional. These transmit a signal from the back that is sufficient enough to
be used in a back course approach.
When flying a back course, the course deviation indicator (CDI) needle
deflects to the opposite side with certain types of equipment. That is, the CDI indicates
to fly left when the aircraft in fact needs to fly right to intercept the approach course.
Reverse sensing does not occur on a horizontal situation indicator (HSI), which gives
correct course guidance during both front-course and back-course approaches.
TACAN
Tactical air navigation system is a navigation system used by military aircraft. It
is a more accurate version of the VOR/DME system that provides bearing and range
information for civil aviation. The DME portion of the TACAN system is available for
civil use; at VORTAC facilities where a VOR is combined with a TACAN, civil
aircraft can receive VOR/DME readings.
ALDIS
It was named after Arthur Aldis who was the British inventor of this signal lamp.
LIGHT FORM
GROUND
Steady green
Clear to take off
Flashing green
Clear to taxi
Steady red
Stop
Flashing red
Vacate runway
Return to starting
point
Caution
Flashing white
Alternating red green
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AIR
Clear to land
Return and wait for
landing signal
Give way to other
aircraft
Do not land
---caution
PAPI, VASI, PVASI, T-VASI
PAPI: Precision Approach Path Indicator lights are used for visual
precision approach. PAPI consists of 4 lights and normally installed left of the
runway with a glide angle of 3°. These lights are visible from 5 NM in day and
20 NM at night. “Two white two red on the path”.
VASI: Visual Approach Slope Indicator lights have 2 types. One is 2-bar
VASI and the other one is 3-bar VASI. VASI lights are normally visible from 3-5 NM
in day and 20 NM at night. VASI provides a glide angle of 3°. Short description
for 2-bar VASI is “red over white you are all right”.
PVASI: Pulsating Visual Approach Slope Indicator lights are visible from
4 NM in day and 10 NM at night. “steady white you are all right".
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T-VASI: consists of 20 light units. 10 either sights of the runway. They
form a cross shape with: 6 lights in a line with the runway, 4 across in a bar.
When high on the approach; 4 lights in each bar show white; and depending
on how high one is, 1, 2 or 3 white lights are visible beyond the bar.
When on the correct path, only 4 bar lights are visible.
When below the approach path: 4 lights in the bar show red. Depending
on how low one is, 1, 2 or 3 red lights are visible in front of the bar.
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AIRPORT LIGHTING
AERODROME BEACON
It's actually a green and white beacon. It helps pilots locate the airport visually,
and identifies what kind of airport it is. The combination of light colors from an airport
beacon indicates the type of airport. For example;
• Flashing white and green for civilian land airports;
• Flashing white and yellow for a water airport;
• Flashing white, yellow, and green for a heliport; and
• Two quick white flashes alternating with a green flash identifying a military airport.
(Two types of beacon: Identification Beacon and the Location Beacon. An Identification Beacon flashing a two
letter identification code in green.
Where the aerodrome is also situated well away from areas of high background lighting, the Location Beacon
would display a flashing White light.
Where the aerodrome is situated in an area where there is a high level of background lighting, such as in the
vicinity of a city where a flashing white light would be difficult to see, the Location Beacon would display a green light
flashing alternately with a white light.)
MINIMUM RUNWAY LIGHTING
1. Runway EDGE lights: Omni-directional white.
2. Runway THRESHOLD lights: Indicates the start of the available landing
distance. They are green and can only be seen from the approach.
3. Runway END lights: They are red and can only be seen in the direction of runway
use. Pilots should not continue a landing roll or taxi beyond the red runway end lights.
SUPPLEMENTARY RUNWAY LIGHTING
1. Centreline Lighting: Centerline lights are white until the last 3000ft of the
runway. The white lights begin to alternate with red for the next 2000ft. For the
remaining 1000ft of the runway, all centerline lights are red.
2. Touchdown Zone (TDZ) Lighting: Touchdown zone lights are installed on some
precision approach runways to indicate the touchdown zone when landing under adverse
visibility conditions. They consist of two rows of light barrettes in order to provide textural
cues in the touchdown area. They start 100 feet beyond the landing threshold and extend to 3,000
feet beyond the landing threshold or to the midpoint of the runway, whichever is less.
3. Rapid Exit Taxiway Indicator Lights: RETILs indicate the distance to go to
the nearest rapid exit taxiway. RETILs consist of 6 yellow lights adjacent to the runway
centreline and configured in a three/two/one pattern spaced 100 m apart; the single light is 100
m from the start of the turn for the rapid exit taxiway.
4. Runway Exit: taxiways may be indicated by substitution of one or two of the
white runway edge lights with blue ones.
5. Stopway Lighting: may be used to show the extent of a stopway beyond the
designated end of a runway. Red unidirectional edge lights visible only in the direction
of runway.
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TAXIWAY LIGHTING
At those aerodromes equipped for low visibility operations, taxiways are equipped
with green centreline lighting, otherwise blue edge lighting is provided.
OPTICAL ILLUSION
Vision is the most important element especially for a safe approach and
landing. Optical illusions are mostly encountered during landing. These
illusions are related with runway width and slope.
A narrow runway causes an illusion that aircraft is higher, so you tend to
make a lower approach. Wider runway causes the opposite.
A downsloping runway also causes a higher approach and upsloping
runway causes the opposite.
To prevent optical illusions, using VASI, PAPI, glideslope, VDP and
checking altimeter frequently are useful.
VDP (VISUAL DESCENT POINT)
Sometimes the MAP is higher than normal, so you can not make a normal 3°
descent to the touchdown zone. A VDP is published for these kind of runways.
If you try to make a landing from a MAP which is higher than normal, in a large or
fast aircraft, you would land long and possibly overshoot the runway. Because of this
reason, VDP is always located before MAP. VDP provides you a standard 3° flight
path to the touchdown zone.
VDP=HAT/300 (The number you get is the distance from the runway threshold in NM.)
HAA (Height Above Aerodrome) & HAT (Height Above Touchdown)
HAA is the height of MDA above published airport elevation. This is published
with circling minimums.
HAT is the height of DA or MDA above the highest runway elevation in the
touchdown zone of the runway. This is published with straight-in minimums.
Hydroplaning
Is caused by a thin layer of standing water that separates the tires
from the runway. It causes reduction of friction between the tires and runway
surface. High aircraft speeds, water, slush, and runway texture are the
reasons for hydroplaning. Braking action is reported by ATC like" good, fair,
poor, nil". If it is nil, directional control may be impossible. If hydroplaning
occurs, landing roll may be longer than the one on smooth ice. You can
estimate the minimum hydroplaning speed;
sqrt of tire pressure times 8,6.
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TORA-TODA-TORR-ASDA(EMDA)-LDA-LDR
TORA - Takeoff Runway Available is the usable length of the runway
available.
The physical length of runway pavement.
TODA - Takeoff Distance Available=TORA+Clearway / 1,5xTORA
Clearway - Obstacle-free area at the end of the runway with the dimension of
75 m. Either side of the extended runway centerline.
TORR - Takeoff Run Required is the measured run required to the unstick
speed (Vr) plus one-third of the airborne distance between the unstick and the
screen height.
(The take off part of the flight is the distance from the brake release
point (BRP) to the point at which the aircraft reaches a defined height.
This defined height is termed the “screen height”.
The screen height varies from 35 ft for class A aeroplanes to 50 ft for
class B aeroplanes.)
ASDA - Acceleration Stop Distance Available=TORA+Stopway
EMDA - Emergency Distance Available=ASDA
Stopway-Unprepared surface at the end of the runway in the direction of
takeoff supporting the aircraft can be stopped in case of an
abandoned/rejected takeoff.
BALANCED FIELD refers to TODA=ASDA
LDA - Landing Distance Available is the length from 50 ft above the
surface of the runway threshold (screen height) to the end of the landing
runway.
LDR - Landing Distance Required is the length from 50 ft above the
surface of the runway threshold (screen height) to the point where the aircraft
reaches a full stop.
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ISA- INTERNATIONAL STANDART ATMOSPHERIC CONDITIONS
At sea level;
Density: 1.225 kg/m3, Pressure: 29.92 inch mercury or 1013.25 mb,
Temperature: 15°,
Environmental Lapse Rate : 2˚C / 1000ft
ATMOSPHERE LAYERS
Troposphere
0 - 36000 ft
Stratosphere
36000 - 160000 ft
Mesosphere 160000 - 280000 ft
Thermosphere
over 280000 ft
3
Ozone layer is characterized by high concentration of O , about 80000ft.
This special type of oxygen molecule absorbs the harmful solar energy and
increases the temperature in that part of atmosphere.
The lapse rate is defined as the rate of decrease with height for an
atmospheric variable. At lower altitudes –I mean, up to approximately 40000ft,
temperature decreases with altitude at a fairly uniform rate. (2º/1000’)
METAR (Meteorological Terminal Aviation Report)
is a routine aviation weather report of current surface weather.
METARs are normally issued hourly.
A special METAR SPECI is issued between routine METAR reports.
SPECI is generated whenever a critical metorological condition exists such as
wind shear or microburst.
TAF (Terminal Aerodrome Forecast)
is a routine weather forecast for an aerodrome. TAFs are usually issued
for a 9-hour period and updated every 3 hours. They may also be issued
for a 24-hour period and updated every 6 hours, but their accuracy is not so high.
VOLMET (Volume Meteorological)
VOLMET is a continuous meteorological information broadcast for aircrafts in flight, on a
VHF/HF frequency. VOLMET includes
1. The actual weather report
2. The landing forecast
3. A forecast trend for the following 2 hours
4. A SIGMET (significant weather, if any) of several selected aerodromes that produce
meteorologic reports within a given region
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WS (Weather SIGMET) or SIGMET (Significant Meteorological Info)
SIGMET is a meteorological broadcast about hazardous weather for all
aircrafts. SIGMETs warn pilots about; severe icing, severe and extreme
turbulence, duststorms, sandstorms, or volcanic ash.
A Convective SIGMET (WST) is issued for hazardous convective weather
such as tornadoes, thunderstorms, hail and covers severe or great
turbulence, severe icing, and low-level wind shear.
Q CODES
QDM - Magnetic bearing (radial) TO the station
QDR - Magnetic bearing (radial) FROM the station
QFE - Zeros the altimeter on the airfield
QNE - 29.92 set by the transition altitude
QNH - Local altimeter setting that altimeter indicates AMSL
QUJ - True bearing TO the station
QTE - True bearing FROM the station
VISIBILITY / RVR
Meteorological Visibility is defined as the greatest horizontal distance
at which a specified object can be seen in daylight conditions. Visibility is
reduced when there are particles in the atmosphere such as; water, ice,
pollution, sand, dust, volcanic ash which absorbs the light.
Runway Visual Range is defined as the greatest horizontal distance a
pilot can see on the runway.
- RVR is not normally reported if it is over 1500m.
- Between 1500 and 800m > it is reported in steps of 100 m.
- Between 800 and 200m > it is reported in steps of 50 m.
- Below
200m > it is reported in steps of 25 m.
RVR is one of the main criterias for especially ILS approach minimums.
INVERSION
When there is an inversion in lapse rate, warm air cannot rise up and
even temperature may increase with altitude. This is called inversion.
Radiation cooling from ground at clear cool nights and warm air mass over
cold air mass cause inversion. Inversion usually causes low visibility, fog,
low ceiling with no wind and no turbulance conditions. At low levels, an
inversion may also cause pollution, with possible adverse effects on health.
16
DEWPOINT (“Çiğ Noktası”)
Is the point below which water vapor will condense into liquid. Dew point
is used to calculate Cloud Base Height;
Cloud Base Height(in ft)=
19°C (surface temp) - 13°C (dewpoint)
1,5(SALR) 2(ELR) 3(DALR)
X lOOO
VERTICAL (CROSS) WIND COMPONENT
Crosswind component of wind can be computed by this formula:
Wind strength x Sin (Rwy Hdg - Wind direction)
AIRMASSES
Air masses are large body of air that have fairly same temperature and
moist. Colder air masses are named as polar or arctic, while warmer air
masses are named as tropical. Fronts are the boundaries between air masses.
FRONTS
Fronts are the boundaries between air masses and generally bring hazardous
weather. Shift in wind direction is the main indication of a frontal passage.
There are 4 types of fronts which are cold, warm, stationary and occluded fronts.
Warm front occurs when a warm air mass moves and slides over a cold
air mass. The boundary between them is named as warm front. It causes low
visibility, low ceiling, rain or snow.
If a pilot flies towards a warm front, he will face cirrus, cirrostarus, altostratus
and nimbostaratus clouds with precipitation and low ceiling progresively. Wind
blows from south, south east.
Cold front occurs when a cold air mass moves and slides under a warm air
mass. The boundary between them is named as cold front. It causes low visibility,
heavy rain, hail even tornadoes, thunderstorm, lightning and gusty winds.
If a pilot flies towards a cold front, he will face poor visibility, rain, lightning,
gusty winds, more cumuluform clouds with decreasing barometric pressure and
lots of weather hazards.
Cold fronts are fast approaching with little or no warnings and they make complete
weather change in few hours. Weather clears rapidly after passage of cold front and
unlimited visibility and dry air develops. On the other hand warm fronts provide advance
warning of their approach by developing stratiform clouds and takes time to pass
through a region.
Stationary front occurs when the forces of two air masses are equal
and affects the local area for some time.
Occluded front; occurs when a faster cold air mass catches a slower
warm air mass. Warm front weather immediatly followed by cold front weather.
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TS occurrence
TS's are one of the most dangerous weather hazards that pilots should avoid.
TS’s are associated with cumulonimbus clouds. It occurs in these conditions;
1. Unstable lapse rate (instability)
2. Some type of lifting action
3. High moisture
There are 3 steps of TS occurrence; cumulus stage, mature stage,
dissipating stage. There are several hazards of thunderstorms such as wind
shear, gusty winds, turbulence, hail, icing, lightning, low visibility and
radio/com interference. Pilots should avoid TS at least 20-25 NM.
Embedded TS is one which is obscured by massive cloud layers and
cannot be seen.
SQUALL LINE
Is a narrow band of active thunderstorms. It develops on or ahead of
cold front, in moist and unstable air. This line is too wide to bypass and too
severe to penetrate.
It forms rapidly and reaches its max. strength at late afternoon and first few
hours of darkness.
CAT (Clear Air Turbulence)
Is commonly defined as high level turbulence and usually faced above
15000ft. There is no visual warning for CAT. So it is hard to detect. CAT is
usually found in jet streams.
CAT has mostly 2000ft deep, 10-20 miles wide and 50 miles long. Long
streams of cirrus cloud formation may show jet stream CAT.
TURBULENCE
Turbulence is the swirl motions in the atmosphere. It may cause stress on
the airframe. There are several types of turbulence which are Low Level
Turbulence, Clear Air Turbulence and Wake Turbulence.
Low Level Turbulence may be faced below 15000ft and occurred
because of surface heating, friction, or ground shapes.
Wake Turbulence is generated by preceding aircraft's wingtips. It is also
called wingtip vortices. The greatest wake turbulence occurs when the
preceding aircrafts is slow, heavy, in clean configuration and at high AoA.
Generally wingtip vortices stay in the air for several minutes. According to
ICAO rules, there is supposed to be separation between aircrafts.
18
WAKE TURBULANCE SEPERATION
H
DISTANCE SEPERATION
5
4
H
L
Others 3 NM
5
M
TIME SEPERATION
T/O
TIME
LNDG
All
2 min
All
Intersection T/O
3 min
L
M/H
TURBULENCE PENETRATION
Maintain level attitude, use VRA as penetration speed and accept
variations in airspeed and altitude.
If you encounter turbulence during approach, increase the airspeed
slightly above normal approach speed to gain more positive control.
VRA: Rough Air Speed (Tubulence Penetration Speed)
WIND SHEAR AND MICROBURST
Wind shear is a sudden, drastic change in wind direction and speed.It may
be upward or downward. This can cause the aircraft to gain or loose sudden
altitude and change airspeed.
Microburst is one of the most dangerous types of wind shear. This type of
wind shear reaches the ground and blow away in all directions. It is intense,
localized down streams as strong as 3000 fpm.
An aircraft can face microburst especially at takeoff or landing. So if
GPWS alerts the pilot about wind shear, the only way to recover is to go
around. Wind shear may be encountered around virga, cumulus formations,
rain shaft or dusting.
( virga: water droplets or ice particles falling down from a cloud and evaporating
before reaching the ground )
19
CLOUDS
There are four types of clouds. These are low level, middle level, high
level and vertically developed clouds.
Low level clouds: this type of clouds are seen from ground to 6500' AGL.
these clouds may contain supercooled water droplets and create icing hazard.
Types of low clouds are stratus, nimbostratus, stratocumulus and fog.
Middle Level clouds are seen from 6500' to 20000' AGL. İn these clouds,
severe icing, moderate turbulence might be faced. Types of middle clouds are
altostarus and altocumulus.
High Level clouds are seen above 20000'AGL.Turbulence an icing are
seldom. Types of this clouds are cirrus, cirrostarus and cirrocumulus.
Vertically developed clouds are independent of altitude. They show lifting
and unstability. All weather hazards such as icing, turbulence, lightinig,
windshear etc can be seen. Types are towering cumulus and cumulunmbus.
FOG
Fog is a cloud that begins within 50 feet of the surface. It typically occurs
when the temperature of air near the ground is cooled to the air’s dewpoint.
At this point, water vapor in the air condenses and becomes visible in the
form of fog.
20
ICING
There are mainly two types of icing; first one is induction, second one is
structural icing.
Induction icing occurs in carburetor or air intake of the engine. It is most likely
to occur when OAT is between -7 and 21C and humidity is above 80%.
Structural icing builds up on any surface of an aircraft causing lost of lift,
increase in weight and control problems. There are two types: rime and clear ice.
Rime ice is normally encountered in stratus clouds. İt has an opaque
appearance. Major hazard of rime ice is the change of the shape of the airfoil and
destroy the lift.
Clear ice normally encountered in cumulus clouds or in freezing rain. It can
glaze the aircraft surface. It is the most serious form of icing because it has the
fastest rate of accumulation.
Freezing rain is most likely to have highest rate of accumulation.
Ice, snow or frost having a thickness of sandpaper can increase the drag by
40% and decrease the lift by 30 %.
When you encounter icing immediate action is for cumulus clouds change of
route/course and for stratus clouds change altitude and switch on all deice
systems. When you encounter freezing rain immediately climb if not possible
make a 180 degrees turn .
There are four levels of icing; trace, light , moderate, severe icing.
Trace: no need for deice/antiice operation
Light: for prolonged exposure (more than one hr) de-ice/anti-ice necessary
Moderate: Deice/anti-ice is immediately necessary
Severe: is beyond capability of deice/anti-ice systems
Frost is hazardous especially at take-off.It is essential to clear frost before takeoff.
Anti-ice : prevents the formation of ice
Deice: remove the ice after it has been accumulated.
The devices used for deice/anti-ice are: Thermal anti-ice, pneumatic deice
boots, windshield anti-ice, alcohol, windshield heater, pitot heater, propeller antiice
Estimating freezing level:
likely to encounter icing.
(OAT/2)x1000 AGL. It is the altitude where you
21
RVSM
Reduced vertical seperation minimum reduces the vertical seperation
between flight levels FL290 and FL410 from 2000' to1000'. Only aircrafts with
specially certified altimeters and autopilots may fly in RVSM airspace.
Additionally, operators must be certified to conduct opertations in RVSM
airspace. But state aircrafts are excepted from this requirement.
Aircrafts to fly in RVSM airspace shall have the following equipment;
- 2 independent working altimeters.
- altitude alert system.
- autopilot
- XNDR with mode C
RNP (Required navigation performance) or PBN
RNP allows an aircraft to fly a specific path between two 3D-defined
points in space. RNAV and RNP systems are fundamentally similar. The key
difference between them is the requirement for on-board performance
monitoring and alerting for RNP. RNAV specification does not have such a
requirement.
RNP provides reduction in greenhouse gases emissions and improved
accessibility to airports located on mountainous terrain.
An RNP of 10 means that a navigation system must be able to calculate its
position to within a circle with a radius of 10 nautical miles.
Various RNP levels are required for different phases of flight. For example
in USA RNP-2 for enroute, RNP-1 for departure and arrival and RNP-0.3 for
approach is utilized.
ETOPS (Extended Range Twin Engine Operations Standards)
According to ICAO standards, a twin engine aircraft operator shall plan its
route to land an aerodrome within 60 minutes in case of an engine failure.
On the other hand, operators which are certified for ETOPS may plan their
routes more than 60 minutes away from a diversion aerodrome in the event of
an engine failure.
Normal ETOPS categories vary between 60 and 180 minutes. In addition
Boeing Company is planning to certify its 787 to 330-minute ETOPS.
ISOLATED AERODROME
Isolated aerodrome term is used when there is no alternate aerodrome. It depends
on the distance to nearest aerodrome, fuel and time required. Additional fuel will be
required to fly for two hours at normal cruise power for turbine power aircraft.
22
FIRST AID KIT REQUIREMENT
According to JAR -OPS 1745, first aid kit requirements is dependent
upon the number of passenger seats installed;
For 0 – 99 > 1 kit
100 – 199 > 2 kits
200 – 299 > 3 kits
300 and more > 4 kits are required.
TYPES OF TURBINE ENGINES
There are 4 types of turbine engines;
Turbojet, Turbofan, Turboprop, and Turboshaft.
Basically Turbofan and Turbojet engines are similar to each other. The
only difference is that the turbofan engine has an additional fan in the inlet
section that separates the inlet air into two parts. One is bypassing the engine
to provide engine cooling and fuel efficiency and helps noise suppression. The
second air flow just like turbojet engine passes through the compressor,
combustor, turbine and exhaust to provide thrust.
Turboshaft and Turboprop are basically the same. Turboshaft engine
drives a shaft that is connected to a gearbox or a transmission while a
turboprop engine is connected to a propeller.
There are 5 sections in an engine;
Inlet, Compressor, Combustor, Turbine (Expansion) and Exhaust.
CRITICAL ENGINE
When one of the engines on a typical multi-engine aircraft becomes inoperative, a thrust
imbalance exists between the operative and inoperative sides of the aircraft. This thrust
imbalance causes several negative effects in addition to the loss of one engine's thrust. The left
engine of a conventional twin-engine propeller-driven aircraft is typically considered critical.
There are two main reasons why the number 1 engine is the critical engine;
(1) Slipstream Effect: If the propellers are rotating clockwise then only the number 1
engine will produce a sideways slipstream force on the fin.
(2) Asymmetric Blade Effect: Propeller blades produce more thrust in the downward
rotation than in the upward rotation
The operating right-hand engine will produce a more severe yaw
towards the dead engine, thus making the failure of the left-hand engine
critical.
23
HIGH LIFT DEVICES
High lift devices are moving or stationary components used to increase lift
during certain flight conditions. There are 2 types of high lift devices;
1. Trailing Edge Flaps increases the lift by extending from the trailing
edge of the wing and has five types.
A. Plain flaps; just change the chord line therefore AOA and lift increases.
B. Split flaps; almost same as the plain, produce just a bit more lift but
more drag as well.
C. Slotted flaps; is like plain flap with gaps between wing and leading edge
of flap. Slotted flap change the chord line thus the AOA and lift. Besides, the
gaps provide higher pressure air to flow upwards of wing to accelerate the
boundary layer over the wing to delay separation of airflow.
D. Fowler flap; is a type of slotted flap change both chord line and area of
the wing, thus increases lift.
E. Slotted fowler flap; is like fowler flap associated with some slots on it to
delay separation of airflow.
2. Leading Edge Flaps; increases the lift by extending from the leading
edge of the wing and has four types.
A. Fixed slot; a nozzle shaped opening that ducts the air onto the top of
the wing to increase the lift at high AOA.
B. Movable slat; is like fixed slot but this time it is deployable by the
operator.
C. Leading edge flaps; is used to increase the camber of the wing to
increase AOA and lift.
D. Leading edge cuffs; are fixed aerodynamic devices, that bends the
leading edge, to increase both CL and camber of the wing. It delays stall.
24
WINGLET FUNCTION
Winglets are aerodynamically efficient surfaces added to wingtips. As it is
known, the high pressure airflow below the wing surface tries to escape upper part of
wing where there is lower pressure at the wing tip. This flow creates wing tip vortices
which is the reason of induced drag. Winglets at the tip of the wings act as a dam to
prevent this flow to decrease the wingtip vortices, eventually the induced drag to
increase the efficiency of wings.
25
STALL
Stall is occurred when the critical angle of attack is exceeded. After this
point, the airflow above the upper surface of airfoil begins to separate
therefore lift production is decreased dramatically. This effect is called stall.
Stall speed is affected by several factors.
1. Weight; When weight increases, AOA needs to be increased to maintain
the same lift. Eventually stall speed is increases.
In addition, forward CG also increases the stall speed. As the CG moves
forward, stabilizer needs to produce more downward force to balance the nose
down attitude. This creates more effective weight, so the weight increases and
stall speed increases.
2. Icing conditions eases the separation of airflow and increases the stall
speed.
3. Turbulent air creates up or down winds causing the relative wind
change rapidly, which may lead AOA to exceed critical angle and stall.
Therefore turbulent air increases the stall speed.
4. As Density of air increases, stall speed decreases. At higher altitudes
density of air decreases resulting lift decreases. So at higher altitudes stall
speed increases.
5. Flaps usage decreases the stall speed since they increase the
coefficient of lift. Aircraft can fly at lower speed without exceeding the critical
angle.
6. Load factor is directly proportional with stall speed. (n=L/W)
Vs=√n*Vs where n is the load factor. As a result as the load factor
increases stall speed increases. For example at the absolute ceiling of an
aircraft level turn maneuver becomes impossible because of stall.
IMSAFE CHECKLIST
I-Illness M-Medication S-Stress A-Alcohol F-Fatigue E-Eating
26
CABIN PRESSURIZE SYSTEM
Cabin pressurization is the pumping of compressed air into an aircraft
cabin to maintain a safe and comfortable environment for crew and
passengers when flying at high altitudes.
Pressurization is essential above 10000ft to protect crew and passengers
from some physiological problems such as; hypoxia, altitude sickness,
decompression sickness, barotraumas.
The most common source of compressed air for pressurization is bleed
air from the compressor stage of a gas turbine engine. Today, the majority of
modern commercial aircrafts have fully redundant, duplicated cabin
pressurization system with a manual back-up control system.
The cabin altitude of an aircraft planning to cruise at 40000ft is
programmed to rise gradually to around a maximum of 8000ft and then to
reduce gently during descent until it matches the ambient air pressure of
destination.
SUPPLEMENTAL OXYGEN REQUIREMENT
PRESSURIZED AIRCRAFT DURING AND FOLLOWING EMERGENCY DESCENT
FOR FLIGHT DECK AND CABIN CREW
Between 10.000 and 13.000 feet
All flight deck and cabin crew for entire flight time minus 30 minutes.
Above 13.000 feet
All flight deck and cabin crew for entire flight
FOR PASSANGERS
Between 10.000 and 14.000 feet
Entire time for 10% of the passengers
Between 14.000 and 15.000 feet
Entire time for 30% of the passengers
Above 15.000 feet
Entire time for all of the passengers.
27
HYPOXIA
Hypoxia is basically caused by lack of oxygen. Symptoms may change
individually, however the common symptoms are headache, euphoria,
cyanosis, increased response time, impaired judgement, limping muscles,
drowsiness and dizziness. There are 4 types of hypoxia.
1. Hypoxic Hypoxia occurs when there are not enough oxygen
molecules in sufficient pressure. This can occur very suddenly at rapid
decompression.
Altitude: Time of useful conciseness:
45000.
9-15 sec.
40000.
15-20 sec.
35000.
30-60 sec.
30000.
1-2 min
25000.
3-5 min
18000.
~40 min
2. Hypemic Hypoxia occurs when CO amount is greater than O2.
Because, blood carries CO easier than O2. This can be seen in piston engine
aircrafts with faulty cabin heating system.
3. Stagnant Hypoxia occurs when there are circulation problems.
G maneuvers, cold weather operations or heart problems may increase the risk.
4. Hystotoxic Hypoxia: occurs when the cells are unable to use O2
effectively. Alcohol, drug or smoking may increase the risk.
FIRE
Class A Fires consist of ordinary combustibles such as wood, paper,
trash or anything else that leaves an ash. Water is used to extinguish.
Class B Fires consist of flammable or combustible liquids such as oil, gasoline
and other similar materials. Dry powder, Halon or foam are used to extinguish.
Class C Fires are energized electrical fires. De-energize the circuit and
use Carbon dioxide to extinguish.
Class D Fires are combustible metal fires such as Magnesium and
Titanium. Only Dry Powder is used to extinguish.
Class K Fires are kitchen or galley fires such as cooking oils, grease or
animal fat. Dry-chemical agent Purple-K is used extinguish.
28
ORGANISATIONS MEMBERS
JAA
- Joint Aviation Authorities. ECAC
Euro Control - Plan/optimize European air traffic management
IATA-International Air Transport Association-is the trade association for
the world's airlines. It represents some 240 airlines or more than 84% of total
air traffic. It was founded in 1945 and its headquarter is in Montreal, Canada.
ICAO-International Civil Aviation Organization is body of the United
Nations. It organises the principles and techniques of international air
navigation. Air Navigation Commission is the technical body within the
ICAO. It was founded in 1947 and its headquarter is in Montreal.
ECAC-European Civil Aviation Conference-is an intergovernmental
organization which was established by ICAO and Council of Europe. It has 44
members including Turkey. It was founded in 1955 and its headquarter is in Paris.
EASA-European Aviation Safety Agency. It is agency of the Eurpean Union
and taking over the functions of Joint Aviation Authorities (JAA). It was
founded in 2003 and its headquarter is in Cologne (Germany).
CIVIL AVIATION HISTORY
Paris Conference (1919) - First international scheduled air service began.
Warsaw Convention (1929) - Ticket / Baggage / Liability
Chicago Convention (1944) - International Air Navigation (Major rules are
set by this convention - ICAO was formed.- Five Freedoms of the Air
1st the right to fly over a foreign country, without landing there
2nd the right to refuel or carry out maintenance in a foreign country on the way to
3rd the right to fly from one's own country to another
4th the right to fly from another country to one's own
5th the right to fly between two foreign countries during flights while the flight
Tokyo Convention (1963) - offences against penal law and any acts
jeopardising the safety of persons on board
Hague (Lahey) Convention (1970) - The act of unlawful seizure (hijacking
of aircraft)
Montreal Convention (1971) - Complements the Hague Convention
29
MOCA, MORA, MCA, MRA, MHA, COP, MEA, MAA, MSA
MOCA; Min. Obstruction Clearance Altitude is the min altitude which
provides obstacle clearance for the entire route, but provides signal
coverage only within 22NM of VOR. 7500T shows MOCA
MORA; Minimum Off-Route Altitude is the minimum altitude which
provides obstacle clearance 10 NM off the route in each side by 1000 or
2000 feet in mountainous area.
Grid MORA; Min.Off-route Altitude is the min altitude published on
enroute chart grid block that provides obstacle clearance of 1000 or 2000 ft in
mountainous area within the grid. It is depicted in blue as first two digits.
MCA; Minimum Crossing Altitude is the min altitude that has to be
gained before reaching that point.
MRA; Minimum Reception Altitude is the lowest altitude that ensures
adequte reception of navigation signals to identify that intersection.
COP; Change Over Point is the point that guiding frequency for that
airway has to be changed to the preceding navaid frequency.
MEA; Minimum Enroute Altitude is the lowest altitude that is depicted on
the airway that provides signal coverage and obstacle clearance for that
part of enroute segment.
MAA; Maximum Authorized Altitude is the maximum altitude for that
airway that provides accurate signal coverage for that part of airway. Above
this altitude the guiding signal may be confused with another navaid.
MSA; Minimum Sector Altitude or terminal arrival altitudes are
established for each aerodrome and provide at least 1000ft obstacle
clearance within 25 NM of the navigation aid, initial approach fix, or
intermediate fix associated with the approach procedure for that aerodrome.
LIGHTNING STRIKE PROTECTION
Lightning strike protection is an important consideration for aircraft design.
When an aircraft is hit by lightning, a very large amount of energy is delivered
to the structure. The basic principle of lightning strike protection is spreading
the energy from the strike over a large surface area to lower it to a harmless
level. The challenge is to keep the energy out of avionics and fuel systems.
The frist step is to minimize and control lightning entry and exit points.
Static dischargers (static wicks) do not reduce or increase the risk of
lightning strike.
I believe the best way is to keep the aircraft out of lightning areas.
Careful flight planning and the use of weather radar are important.
30
RATE OF TURN/RADIUS OF TURN
ROT is the nu. of degrees of hdg change that an a/c makes. (expressed in deg per sec)
ROT=
R=
1091 x Tan (Bank Angle)
Airspeed (in knots)
V²
11,26X Tan (Bank Angle)
As speed increases RateOT decreases.
As speed increases R increases.
Radius of turn is related with RateOT.
THE FORCES ACTING ON AN AEROPLANE
The forces acting on a plane are lift, weight, thrust and drag.
When lift and weight are equal, an aircraft will maintain a level attitude.
To climb, lift must exceed the aircraft weight.
When thrust and drag are equal, an aircraft will maintain a steady speed.
To accelerate, thrust must exceed the drag value.
In a banked turn, weight is constant, but lift is lost due to the reduction in
wing span. Therefore, to maintain altitude in a banked turn, lift must be
increased by increasing speed or AoA.
LIFT
Lift is the force generated by the pressure difference between the upper
and lower surface of an aerofoil which is facing the air with a certain speed. An
aerofoil is cambered on its top side and flattened on its bottom, so the air
facing aerofoil separates into two parts. The air on top of the wing travels
faster than the air on the bottom. Faster air produces less pressure than
slower air as in the Bernoulli principle. Lift can be formulated as;
CL depends upon the angle of attack and shape of that specific wing. By
moving the elevators, basically AOA is changed therefore the lift. Lift is
assumed to be acting on center of pressure of the aerofoil. CP moves forward
as the AOA increase and moves backward as the AOA decrease.
31
DRAG
Drag is the resistance to motion of an aircraft through the air. It’s parallel
to the relative airflow. It has 2 major components;
PARASITE DRAG
Parasite drag is caused by the relative motion of the aeroplane wing to
the air. Parasite drag increases directly with speed because more air
molecules resist the motion of the aircraft through the air.
Parasite Drag α CAS²
INDUCED DRAG
Induced drag is caused by the production of lift and it’s related with the
wing-tip vortices. Induced drag is greatest at lower speeds due to the high
angles of attack required to maintain the necessary lift.
Vmd (Minimum drag speed)
Vmd is the speed at which parasite and induced drag values are equal.
THE EFFECT OF AEROPLANE WEIGHT ON DRAG
If you increase the weight, the
aeroplane requires more lift causing
an increase in the induced drag.
i.
More drag at all speeds
ii. Vmd is at a faster speed.
THE EFFECT OF FLAPS AND UNDERCARRIAGE ON DRAG
The extension of the flaps and
undercarriage results an increase in
the parasite drag.
i.
More drag at all speeds, and
ii.
Vmd is at a slower speed.
32
SPEED STABILITY
Speed stability is the behavior of the speed after a disturbance at a
fixed power setting.
Speed stable:
1. An increase in speed means an increase
in drag, thus causing a return to the original speed.
2. A decrease in speed means a decrease
in drag, thus causing return to the original speed.
Speed unstable:
1. A decrease in speed means an
increase in drag. This causes a further
decrease in speed.
2. A increase in speed means a decrease
in drag. This causes a further increase in
speed.
WEIGHT
The weight of an aeroplane always
acts vertically straight down from
the aeroplane’s center of gravity.
W=mg
THE RELATIONSHIP BETWEEN FORCES IN DIFFERENT PHASES OF FLIGHT
STEADY, STRAIGHT-ANDLEVEL FLIGHT
In straight and level flight, the flight
path and the relative airflow are
horizontal. This means that lift will
be vertical and drag horizontal.
L=W and T=D
STEADY CLIMBING FLIGHT
In a straight climb at the same
airspeed, the forces in any opposite
direction must be equal.
T=D+ W sinӨ
L=W cosӨ
33
STEADY DESCENDING FLIGHT
In a straight descent at the same
airspeed, the forces in any opposite
direction must be equal.
D=T+ W sinӨ
L=W cosӨ
THE GLIDE
Glide means a descent with no thrust.
D=W sinӨ
L= W cosӨ
Also;
TanӨ= D / L
This means that only lift to drag ratio determines glide range and not aeroplanes weight.
However, the heavier aircraft would have a higher airspeed than the lighter aircraft, and,
therefore, although it would glide the same distance, it would take less time to do so.
WEIGHTS
Aircraft authorized gross weight limits are laid down in the aircraft flight
manuals (AFM). The authorized operation limits may be equal to or lower than
the structural design weight limits.
Max Ramp Weight (MRW)-Max Taxi Weight (MTW) is the max weight
authorized for maneuvering (taxiing or towing) on the ground as limited by aircraft
strength and airworthiness requirements. It includes the taxi and run-up fuel.
It is greater than the maximum takeoff weight due to the fuel that will be
burned during taxi and run-up operations generally for 10-15 minutes.
Max Takeoff Weight (MTOW)-Max Brake Release Weight is the max
weight authorized at brake release for T/O, or at the start of the T/O roll.
In operation, T/O weight may be limited by; aircraft performance,
environmental conditions, runway length and altitude, max tire speed
and brake energy, obstacle clearances and enroute and landing weight
requirements.
Maximum Landing Weight (MLW) is the maximum weight authorized for
normal landing of an aircraft. The MLW must not exceed the MTOW.
In operation, landing weight may be limited by aircraft performance,
airfield characteristics, approach and landing requirements and noise
requirements.
34
Maximum Zero Fuel Weight (MZFW) is the total weight of the airplane
and all its contents, minus the total weight of the usable fuel on board
(unusable fuel is included in ZFW). It is the max weight permitted before
usable fuel and other specified usable fluids are loaded in specified sections of
the airplane. The MZFW is limited by strength and airworthiness requirements.
BEM+VL=DOM
TOM=Ramp Mass-Taxi Fuel
DOM+TOF=OM
TL+TOF=Useful Load
OM+TL=TOM
DOM+TL+TOF=TOM
DOM+TL=ZFM
ZFM+TOF=TOM
EFFECT OF WEIGHT ON AIRCRAFT PERFORMANCE
Weight has 2 adverse effects on performance in terms of amount and
balance. Firstly effects of weight itself are;
- higher take off speed
- longer take off run
- reduced rate of climb and angle
- lower maximum altitude
- lower cruise speed
- shorter range due to fuel consumption
- reduced maneuverability
- higher stall speed
- higher approach and landing speed
- longer landing roll
- excessive weight on landing gear
Secondly imbalance of weight will affect flight characteristics adversely.
For example; fuel load imbalance will cause one wing to be heavier or
overload to aft will cause nose up attitude or vice versa.
FORWARD CG
Increases stability, decreases
controlability
Take-off
more
elevator
requires, so later lift-off
Hard to climb
More drag (trim drag)
Needs more lift so higher stall
speed
Requires more thrust
Both range and endurance
decreases
AFT CG
Decreases stability, increases
controlability
Take-off
less
elevator
requires, so earlier lift-off
Less drag (trim drag)
Needs less lift so lower stall
speed
Requires less thrust
Both range and endurance
increases
35
TERMINOLOGY
THE CHORD LINE
Is a straight line from the leading edge to the trailing edge of an aerofoil.
THE MEAN CHAMBER LINE
Is a line from the leading edge to the trailing edge with equal distances to the upper
and lower surfaces of an aerofoil.
ANGLE OF ATTACK
Is the angle between the chord line of an aerofoil and the relative airflow.
ANGLE OF INCIDENCE
Is the angle between the chord line and the aircraft’s longitudinal datum. It’s a fixed
angle for a wing but may be variable for a tailplane.
COEFFICIENT OF LIFT (CL)
Coefficient of lift is the lifting ability of a wing. It depends on both the shape of the
wing and the AoA.
CENTER OF GRAVITY (CG)
Is a single point at which the distribution of total weight on a body is balanced.
Improper loading or accidentally shifting of cargo in the air might cause out of
range CG conditions, and may result accidents. Crash of B747-400 (National Airlines
Flight 102) in Afganistan in April 2013 was a good example for this condition. It
crashed due to shifting of its cargo during T/O.
CENTER OF PRESSURE
Is a single point where the lifting force is produced. (not a fixed point)
ASPECT RATIO
The ratio of wing span to average chord.
High aspect ratio = high lift but incapable of higher speeds because of Drag. (gliders)
Low aspect ratio = lower lift but capable of higher speeds. (fighter jets)
36
TRANSPONDER CODES
7500 hijack
0033 parachuting operations
7600 comm failure
7000 VFR when no other code has been assigned.
7700 emergency
Although codes can be assigned from 0000 to 7700 the number of possible codes to
be set is 4096.
Mode A: 4 digit code entered by the pilot (Mode 3)
Mode C: Pressure altitude information is sent
Mode S: selective interrogation facilitates to transmit 24 bit address length of data to
other aircrafts Xpndr, TCAS, ACAS, and ADS-B systems. The data to be transmitted
are callsign, heading, altitude.(ADS-B: Automatic Dependent Surveillance-Broadcast)
V SPEEDS
V1: T/O Decision Speed
V2: T/O Safety Speed: The speed at which the aircraft may safely become airborne
with one engine inoperative.
VR: Rotation Speed: the speed to start raising the nose during the takeoff run.
VMCA: Min Control Speed In T/O Config – the minimum CAS at which the aircraft
is directionally controllable in flight with a sudden critical engine failure and takeoff
power on the operative engine(s)
VMCG: Min Control Speed On The Ground - the minimum airspeed at which the
aircraft is directionally controllable during acceleration along the runway with one
engine inoperative, takeoff power on the operative engine(s), and with nose wheel
steering assumed inoperative.
VX: Best Angle of Climb Speed: The airspeed that provides the best angle of climb
(highest altitude in shortest distance). It is typically a fairly slow speed, and is most
useful for taking off over obstacles like trees.
VY: Best Rate of Climb Speed: The airspeed that provides the best rate of climb
(highest altitude in least time). It is faster than Vx, and is most useful for getting to
an altitude as quickly as possible (used to avoid icing).
VRef: Landing Reference Speed: at a point 50ft above the threshold. It’s not less than 1,3
times the stall speed in the normal landing config. In simple terms, your final app speed.
VRA Rough Air Speed: Tubulence Penetration Speed
VMD Min Drag Speed is the speed at which parasite and induced drag are equal.
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IAS & CAS & EAS & TAS
IAS: is the airspeed read directly from the airspeed indicator on an aircraft. It uses the
difference between total and static pressure, provided by pitot-static system.
CAS: The airspeed indicator is subject to slight errors. These errors are caused by the
position of the Pitot Tube and Static Ports. CAS is the IAS corrected for these
instrument and position errors.
EAS: Equivalent Airspeed is the CAS which is corrected for compressibility of the air. By
the way, the air is considered as not compressible below ≈300kts.
TAS: is the speed of the aircraft relative to the airmass in which it is flying. At sea
level in the ISA and at low speeds where air compressibility is negligible, IAS equals
to TAS. TAS increases approximately 2% over IAS for every 1000ft.
NEWTON’S LAWS
1 ST LAW: A body at rest tends to remain at rest, and a body in motion tends
to remain moving at the same speed and direction.
2 ND LAW: When a body is acted upon by a constant force, its resulting
acceleration is inversely proportional to the mass of the body and is directly
proportional to the applied force. F=ma
3 RD LAW: Whenever one body exerts a force on another, the second body
always exerts on the first, a force that is equal in magnitude but opposite in direction.
COMPASS ERRORS
There are 4 types of errors regarding the compass.
Variation error; Magnetic north and geographic north are different from each
other. In aviation difference between true and magnetic pole is called variation.
This variaton numbers are published on the charts easterly and westerly. To calculate
true heading, easter corrections should be substracted, while westerly corrections be
added to magnetic heading.
Deviation; Local magnetic fields in aircraft affect the compass. This error is called
deviation. Compass correction card is used to compansate the error. These errors are
changable according to intended heading.
Dip error; This error occurs because of the magnetic flux enters the nort pole
vertically which makes flux parallel to surface over equator and perpendicular over the
poles. When performing a compass turn to northerly heading, you must roll out before
reaching the desired heading and visa versa in northern hemisphere.
Oscillation error; Oscillation is a combination of the other errors. To compensate
this error use the average indication.
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FLY BY WIRE TECHNOLOGY
FBW technology replaces the conventional manual flight controls, such as
tubes, rods or bell cranks. By means of this technology, pilot’s or autopilot's control
inputs are converted into electronic signals and transmitted to actuators attached to
control surfaces by wires. That is why this system is called FBW. This system help
designers to reduce weight of aircraft. On the other hand the main concern is
reliability. While traditional mechanical or hydraulics system fails gradually, FBW
system may collapse immediately and cause the aircraft be uncontrollable. To prevent
this situation, redundant systems has been developed such as completely independent
computers, wirings, actuators to take over in case one system fails. On the other hand,
in some aircrafts a mix of FBW and conventional systems as back up. Airbus 320 is
using this kind of system. However, Boeing 737 is not using FBW technology.
FUEL MANAGEMENT
Fuel management is so vital for the operation of an aircraft. At all stages of
flight, the flight crew must be vigilant regarding their fuel state and, to the maximum
extent possible, adhere to Company policies and fly the planned profile. The effects of
poor in-flight fuel management can be broadly divided into three primary categories.
These categories are Operational, Legal and Financial.
OPERATIONAL: Poor in-flight fuel management can lead to divert to a new
destination to refuel. In the worst case, poor in-flight fuel management can lead to fuel
exhaustion and forced landing with the potential of the loss of aircraft and loss of life.
LEGAL: Regulations dictate the minimum amount of fuel required for a given
flight profile. Failure to comply with these regulations can lead to enforcement action
and to the potential of administrative action (suspension of AOC, loss of licence, etc)
or financial penalties being assessed against the pilot, the Company or both.
FINANCIAL: Poor in-flight fuel management can result in inefficient use of
the available fuel leading to higher consumption and increased cost.
DIFFERENCE BETWEEN HELICOPTER AND AIRPLANE
To be able to create lift, a plane must have some type of foward motion to gain
airflow over its wings. Where as the helicopter can simply rotate its main rotor
(wings) in a circle to create lift, without needing to have a forward motion. Thus
airplanes must roll along the runaway to take-off.
Disadvantages of helicopter are speed, capacity and operating cost.
On the other hand, a helicopter can take off or hover at zero forward speed.
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GREAT CIRCLE – RHUMB LINE
GREAT CIRCLE: A great circle track is a line of shortest distance between two points
on a sphere (or a flat surface) with a constantly changing track direction as a result of
convergence.
RHUMB LINE: Rhumb lines are tracks with a constant track direction between two
points on a sphere and therefore must be a longer distance than a great circle track.
CONVERGENCY: Convergency represents the change of direction experienced along
eastwest tracks, except rhumb lines, as a result of the way direction is measured due to the
effects of converging meridians at the poles. The change of direction experienced between two
points is known as convergency. Convergency is clearly dependent on latitude; it is zero at the
equator,where the meridians are parallel, and a maximum at the poles, where the meridians
converge. It is also dependent on how far you travel.
HIGH SPEED FLIGHT
(Actually I’ve never flown at high speeds in terms of aerodynamics.)
At speeds over 260 knots, air is considered incompressible and its density
remains constant, but its pressure changes. Air acts like water. Although aircraft is
flying subsonic, airflow over the wings may reach sonic speeds. When the velocity of
flow reaches sonic speed, further acceleration results shock-wave formation. This
shock wave increases drag, decreases stability and degrades controllability.
At high speed flight, SPEED REGIMES can be defined in 4 categories;
Subsonic - up to 0.75 mach
Transonic - 0.75 - 1.2 mach
Supersonic - 1.2 - 5 mach
Hypersonic - above 5 mach
Critical mach number is the boundary speed between subsonic and transonic flight.
After critical mach number, drag rises sharply, trim and stability changes causing
a decrease in controllability.
As altitude increases, TAS increases and LSS decreases so the mach number
increases. To prevent speeding up beyond critical mach number, at flight levels above
mid twenties, mach number is used.
To delay seperation, so to increase critical mach number vortex generators and
sweep back wing design are used.
If an aircraft flies at absolute ceiling, it can not speed up due to critical mach
number and slow down due to stall speed restriction. This point is Coffin Corner.
(MACH NUMBER: Mach number is the ratio of the speed of an object (or flow) to
the local speed of sound. M=V/VSOUND )
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KARMAN LINE
The Karman Line commonly represents the boundary between the Earth's
atmosphere and outer space and lies at an altitude of 100 kilometres (62nm)
above the Earth's sea level.
AIRCRAFT ACCIDENT INVESTIGATION
Investigation of accidents consists of 3 phases:
a) collection of data,
b) analysis of data,
c) presentation of findings.
1.
2.
3.
4.
5.
Aircraft performance
Meteorology
Systems
Crash Dynamics
Accident Side Management
Trans World Airlines FLIGHT 800
A Boeing 747-100, exploded and crashed into the Atlantic Ocean near New York, in
July 1996, 12 minutes after takeoff from John F. Kennedy International Airport on a scheduled
international passenger flight to Rome, with a stopover in Paris. All 230 people on board were
killed, the third-deadliest aviation accident to occur in U.S. territory.
While accident investigators from the NTSB traveled to the scene, arriving the following
morning, there was much initial speculation that a terrorist attack was the cause of the crash.
Consequently, the Federal Bureau of Investigation (FBI) initiated a parallel criminal
investigation. Sixteen months later the FBI announced that no evidence had been found of a
criminal act and closed its active investigation.
The four-year NTSB investigation concluded with the approval of the Aircraft Accident
Report in August 2000, ending the most extensive, complex, and costly air disaster
investigation in United States history. The report's conclusion was that the probable cause of
the accident was an explosion of flammable fuel/air vapors in a fuel tank, and, although it
could not be determined with certainty, the most likely cause of the explosion was a short
circuit. As a result of the investigation, new requirements were developed for aircraft to
prevent future fuel tank explosions.
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