Aircraft Operations Flashcards
Define Mass
Quantity of matter in a body (not related to local gravity)
What is IAS
Indicated airspeed - what’s displayed directly to the pilot
Define TAS
True airspeed - the speed of the ACFT relative to the air mass
Define Mach Number (M)
The velocity of the ACFT relative to the local speed of sound
Define GS
Ground speed - Speed of the ACFT over the surface
What is Newtons 3rd law?
For every action, there is an equal and opposite reaction
What is Bernoullis Principle?
- Increasing speed of a fluid occurs simultaneously with a decrease in static pressure (and temperature decreases)
- Conversely a decrease in speed of a fluid will occur simultaneously with an increase in static pressure
N.B. Air treated as a fluid
What are the 4 forces operating on an aeroplane?
- Lift
- Weight
- Thrust
- Drag
What is lift?
The force generated by the flow of air over the wings of an ACFT. It is also generated by the tailplane and, albeit less efficiently, by all parts of the structure
What is weight?
- The heaviness of matter (related to local gravity)
- The weight of an ACFT is the effect of gravity acting on its mass, attracting it vertically down towards the centre of the Earth. Acts through the ACFTs centre of gravity
- C of G can be represented by the following symbol
What happens to Centre of Gravity in flight?
Fuel is normally stored in the wings and fuselage tanks. As the fuel burns in flight, the position of the centre of gravity will alter.
N.B. Many ACFT can transfer or cross feed fuel between various tanks to ensure the weight of fuel is distributed evenly
What is thrust?
- The force generated by the engine(s) giving the ACFT forward movement
- Thrust acts through the thrust line of an ACFT
What is drag?
- The resistance experienced by an ACFT as it moved relative to the air
- Drag acts through the drag line of an ACFT which is parallel and opposite to thrust
What directions to the 4 forces of an ACFT act?
In straight and level flight __________ balances__________ and __________ balances __________
- Lift
- Weight
- Thrust
- Drag
What happens to lift and weight in a turn?
- Lift always acts perpendicular to the aerofoil
- Weight always acts vertically down due to gravity
- Resultant lift will be less than the weight so unless the pilot intervenes, ACFT will descend
What happens when an ACFT accelerates?
- Airflow over the wings increases, resulting in increased lift, the ACFT climbs
- Conversely, as airflow over the wings decreases, lift reduces, the ACFT descends
What is an aerofoil?
A device which gets a useful reaction from air moving over its surface
Any part of an ACFT designed to produce lift
- Wings
- Tail surfaces
- Propellers
- Some designs use the fuselage too
What is the front of an aerofoil called?
Leading edge
What is the rear of an aerofoil called?
Trailing edge
What is a chord line?
Joins the leading and trailing edges. The angle the wing is attached to the fuselage
What is the angle of incidence?
The angle between the chord line (the angle the wing is attached to the fuselage), relative to the ACFTs longitudinal axis
What is the longitudinal axis?
The line through the fuselage of an ACFT from nose to tail
What is the angle of attack?
The is the angle formed by the chord line and the relative airflow - not necessarily same as the angle of incidence
What is the boundary layer?
The air directly in contact with the surface on an aerofoil
If the boundary layer remains in contact with the surface of an aerofoil, the flow is said to be __________
Laminar
N.B. An aerofoil designed for minimum drag and a smooth flow of the boundary layer is called a laminar aerofoil
Can laminar flow always be maintained?
No
What is the point called at which air flow becomes turbulent on an aerofoil?
Transition point
What is the point called at which the air flow separates from an aerofoil?
Separation point
How is lift affected in turbulent flow?
- As of flow over the top of an aerofoil becomes turbulent, its velocity reduces. Bernoullis principle - this increases pressure
- As pressure above and below the wing equalises, lift is reduced and is eventually lost all together, causing the aerofoil to stall
When does stalling occur?
When the critical angle of attack is exceeded - for most aerofoil, this is around 15º
N.B. The angle of attack can be simply described as the difference between where a wing is pointing and where it is going
How does angle of bank affect the stall speed?
As angle of bank increases, the stalling speed increases significantly
How can a pilot recognise stalling?
- ACFT handling will change, often the controls will become heavy and the airframe will buffet.
- Many ACFT fitted with a stall warner device
- Larger ACFT sometimes fitted with mechanical stick shaker
Stall prevention and recovery
In almost all circumstances, pushing the control column forwards will reduce angle of attack and un-stall ACFT
N.B. Mandatory for student pilots to be taught stall awareness and recovery techniques before first solo
Label the following diagram
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Label the following diagram
ACFT can manoeuvre in 3 dimensions. All 3 axes pass through the ACFTs centre of gravity. Label the following diagram
An ACFT __________ about the lateral axis using the __________
Pitches
Elevators
N.B. Easing the control column backwards raises the nose, easing forward lowers it, relative to the horizon
An ACFT __________ about the longitudinal axis using the __________
Rolls
Ailerons
N.B. Turning the control column to the left rolls the ACFT to the left. Turning it right rolls the ACFT to the right
An ACFT __________ about the vertical axis using the __________
Yaws
Rudder
N.B. Pressing the left rudder causes the nose of the ACFT to turn left and vice versa for the right pedal
What are the secondary effects of controls?
- Ailerons - adverse yaw
- Rudder - adverse roll
What is an elevon?
Aileron and elevator combine
N.B. Used in delta winged and tailless ACFT
- All ACFT can be trimmed in __________ - elevator adjusted
- Many ACFT can be trimmed in __________ - rudder adjusted
- Some ACFT can be trimmed in __________ - ailerons adjusted
- Pitch
- Yaw
- Roll
N.B. Large aerodynamic forces on ACFT control surfaces can result in resistance in control yoke. Trim tabs on these surfaces can be adjusted to reduce these forces to zero
What are the 3 types of stability?
- Stable - ACFT tends to return to its original condition
- Neutrally stable - ACFT will assume a new position
- Unstable - ACFT will continue to diverge from its original condition
N.B. Depending on its operational use, an ACFT will be designed to have a degree of stability in one or more axes
What is stability in the roll known as?
Lateral stability
N.B. Although roll is movement about the longitudinal axis
What is stability in the pitch known as?
Longitudinal stability
N.B. Although pitch is movement about the lateral axis
What is stability in yaw known as?
Directional stability
N.B. Although yaw is movement about the vertical axis
What are dihedral wings?
Wings which are angled upwards from the fuselage - they reduce the loss of resultant lift when the ACFT is banking and increase lateral stability
What are anhedral wings?
Wings angled downwards from the fuselage - Improves roll rate by reducing lateral stability
N.B. Sometimes used in high wing ACFT as they can be “too stable” due to a higher centre of gravity
Define Drag
The aeronautical term for the air resistance experienced by the ACFT as it moves relative to the air
N.B. Acts in opposite direction to motion through the air i.e. thrust
N.B.B The lower the drag, the less thrust required to balance it, therefore reducing drag is desirable
What are the 2 main types of drag?
Parasite drag and induced drag
What is induced drag?
- Unavoidable by-product of lift and increases as angle of attack increases
- Only created when a wing generates lift so when an ACFT is accelerating along the runway with 0 angle of attack, there is only parasite drag. No induced drag
- Manifested as vortices at the trailing edge of the wing and especially at wing tips as someair from the high pressure area under the wing spills over around the wingtip to the low pressure area above the wing
- Operationally, vortices are considered to exist from to when the nose wheel lifts on take off until it touches down on landing
N.B.When high value of lift is being produced, e.g. at low speed and high angle of attack such as in approach phase and climb out - the pressure difference between under the wing and over results in very strong wingtip vortices
What is parasite drag?
Not directly associated with development of lift. It has 2 further sub groups - profile drag and interference drag
N.B. Profile drag further divided into 2 subgroups; skin friction and form drag
What are the 2 further subgroups of profile drag?
Skin friction and form drag
What is skin friction?
Results from the friction forces existing between an object and the air through which it is moving
What does the magnitude of skin friction depend on?
- The surface area of the ACFT. The whole surface area of the ACFT experiences skin friction drag as it moves through the air
- Whether the boundary layer airflow near the surface is laminar or turbulent. A turbulent boundary layer causes drag
- Roughness on a surface (including ice) will increase skin friction. Flush riveting and polishing are attempts to smooth the surface and reduce skin friction drag
- An increase in airspeed increases skin friction drag
- An increase in aerofoil thickness increases skin friction drag from the wing
What is form drag?
Results when the airflow separates from the surface of the aerofoil. Eddies are formed and the streamlined (laminar) flow is disturbed. The turbulent wake formed increases drag
What is the difference between skin friction and form drag?
Easiest way to understand the difference is to consider a flat plate in 2 different kinds of attitude relative to airflow
- When the flat plate is at zero angle of attack, the drag is all skin friction
- When the flat plate is perpendicular to the, the drag is all form drag
How can form drag be reduced?
Streamlining in order to help delay separation from the boundary layer. This can be achieved with thing such as:
- Flush rivets
- Adding fairings to other parts of the airframe such as undercarriage and propeller spinners
What is interference drag?
Occurs when a substantial change of airflow direction occurs over an airframe such as at the junction of ACFT surfaces e.g where wing joins the fuselage. Interference occurs
N.B. Can be reduced with with suitable filleting, fairings and streamlining
When is induced drag the highest?
When an ACFT is flying slowly, at a heavy weight and in a “clean” configuration, such as in the early stages of climb
Why is induced drag significant?
- Intense vortices created as a byproduct of lift can be extremely hazardous to ACFT flying through them
- More persistent in calm conditions
- Normally invisible
How can induced drag be reduced?
- High aspect ratio wings - Long narrow wings such as gliders
- Winglet and sharklets - can also be retrofitted to older ACFT
- Advanced wing design and use of composite materials - nature as inspiration
What is the effect of streamlining?
Reduced interference and form drag
What are 3 main categories of device which modify lift and drag?
- Trailing edge devices - flaps
- Leading edge devices - slots, slats and flaps
- Spoilers/airbrakes
How do flaps increase lift?
- Pressure difference is created on with as air flows faster over the upper surface of a wing than the lower surface (Bernoullis Theory)
- Difference in velocity results from the camber of the wing - this directly relates to how much lift the wing produces
- Flaps increase the camber of the wing, resulting in more lift
Examples of leading edge high lift devices?
- Leading edge slots - fixed devices on wings which allow some high pressure air from the underside to bleed onto the upper side, delaying the boundary layer separation
- Leading edge slats - Perform a similar function to slots and alter the wing camber but are retractable
- Leading edge flaps - AKA Krueger flaps are hinged sections of the leading edge which are pushed forward to alter the wings camber
N.B. Incorrect use can have have catastrophic consequences
What are spoilers?
- Small hinged plates on the upper surface of wings
- When deployed, they disturb the airflow over the wing so drag is increased and lift is decreased
- Most frequently used on landing to dump lift and make braking more efficient
What are the effects of failure of high lift devices on ACFT approaching to land and ACFT taking off?
Affect ACFT performance
- Higher approach speed needed to generate adequate lift - not as much drag can be generated
- Shallower approach and climb gradient - problems with obstacle clearance
- Longer TKOF and landing roll needed to attain and reduce speed
- Less efficient braking - hot brakes, tyre failures, runway excursion)
- Flap asymmetry resulting in rolling movement
How is the use of flaps and slats often limited?
By the speed of the ACFT. Deploying flaps beyond the flaps extended or VFE speed could result in structural damage to the airframe
What are ADF and NDB?
Automatic Direction Finder and Non-Directional Beacon
- ADF used in conjunction with an NDB to provide aid for ACFT navigation
- ADF indicates the relative bearing of the tuned NDB and/or its QDM/QDR in the cockpit on Relative Bearing Indicator (RBI)
N.B. NDB is a ground based navaid
What is a VOR?
VHF Omnidirectional Radio Range
- Used in conjunction with VOR equipment onboard ACFT (consists of a receiver, antenna and indicator)
- Indicates to a pilot which radial the ACFT is on but does not indicate position or heading
- Information received can be presented on a Course Deviation Indicator (CDI) or Relative Magnetic Indicator (RMI)
- OBS - allows you to intercept a radial to/from
N.B. Ground base navaid
What is a DME?
Distance Measuring Equipment
- Gives slant range in nautical miles from and time to DME station and ACFTs ground speed
N.B. Ground based navaid
What is TACAN?
Tactical Air Navigation
- Essentially a military version of a VOR/DME system and operated on UHF
- More accurate than a VOR
- Some are equipped with a civil VOR beacon and are then called a VORTAC
- The symbol on a chart for a TACAN is the following
N.B. A military system ground based navaid
What is an ILS?
Instrument Landing System
Consist of:
- Localiser transmitter
- Glide path transmitter
- Outer marker (or an NDB or other fix).
- In association with a suitable runway, the approach lighting system
What are the errors and abnormal indications associated with ADF/NDB?
- Designated operational coverage
- Mountain Effect
- Static interference
- Night effect
- Station interference
- Coastal refractions
- Lack of failure warning system
What are the errors and abnormal indications associated with a VOR?
- Site error - caused by uneven terrain. However this is monitored to +/-1º accuracy
- Propagation error - long range causes signal to bend
- Airborne equipment error - caused by ACFT equipment assessing and converting phase difference into a radial. Error should not be greater than +/- 1º
The above errors aggregate errors giving a maximum total of +/- 5º
N.B. VOR is more accurate than NDB but is more expensive to install and maintain
What is QDM?
Magnetic bearing to
What is QDR?
Magnetic bearing from
What are the advantages and disadvantages of DME?
Advantages
- DME can be frequency paired with associated VOR
- Simple to use and can calculate ground speed
- Pilots can give accurate estimates of arrival times over positions
- A very accurate fix can be obtained using 2 DME stations
Disadvantages
- Only gives slant range - not accurate at high altitude and 0 nautical miles not possible
How is an ILS classified?
By category in accordance with the capabilities of the ground equipment
- Category 1 - ILS approach and a decision height (DH) of not less than 200ft
- Category 2 - ILS approach and a DH of not less than 100ft
- Category 3 - Guidance to touchdown and roll out along the runway. No decision height!
What do the localiser and glide path transmitters do and what are their frequency bands?
Localiser Transmitter
- Provides lateral guidance
- Same frequency band as VOR transmitters (Between 108.10 MHz and 111.95MHz)
Glide Path Transmitter
- Provides vertical guidance during the approach
- UHF radio transmitter in band (Between 329.30 MHz to 335.00 MHz)
What are the advantages and disadvantages of an ILS?
Advantages
- Pilot interpreted and simple to use
- Precision approaches possible - i.e. provides full guidance in azimuth and elevation, in some cases during the landing roll out
- Can be coupled to auto-pilot for automatic approach and landings
Disadvantages
- Subject to interference from commercial VHF radio stations
- Reflections from other ground facilities can create false glide paths
- Shortage of frequencies
What is an MLS?
Microwave Landing System
What is a precision approach system?
Vertical and lateral guidance
Piston engines in ACFT are virtually identical to this in automobiles but with 3 important differences. What are these?
- Most are air cooled - saves weight and is safer
- Dual ignition systems
- Fuel/air mix can be adjusted manually
What are the 5 operations which take place in a 4 stroke engine?
- Induction - fuel/air mixture goes in via intake valve and piston goes down
- Compression - Both valves closed and piston rises, compressing the fuel/air mixture
- Spark plug ignites fuel/air mixture just before piston reaches the top
- Power - Fuel/air mixture explodes, increasing pressure and forces piston down
- Exhaust - exhaust valve opens and burned gases escape, clearing the cylinder
What is a carburettor?
A device which combines fuel and air. Air flowing through the carburettor draws fuel from a reservoir through a Venturi tube
In a carburettor, as air passes through the Venturi section, what 3 things happen?
- The air accelerates
- Drop in air pressure (Bernoullis principle)
- This causes fuel to be drawn through the main jet where it mixes with air in the venturi
N.B. Fuel/air mixture is then fed to each cylinder in turn
What is one of the main problems with a carburettor?
Carburettor icing
What causes carburettor icing in Venturi type carburettors?
- In the Venturi, air accelerates and pressure drops which is accompanied by by an instant drop in temperature
- When the fuel changes from a liquid to a vapour, latent heat is required and this is taken from the air so the air cools even further
- With this double cooling effect, the temperature of the air may drop as much as 20ºC
- When flying through visible moisture or in high humidity, there is a high chance that water vapour will deposit as ice in the carburettor
- This can choke the engines air supply and can cause it to stop
How can carburettor icing be avoided?
- If possible, avoiding areas (geographically and/or by flying above or below levels) where moisture is present and icing likely
- Regular application of carburetor heat. The carb heating system ducts warm air from the exhaust to the Venturi to melt Carb heat is routinely applied before engine power is reduced below around 1800 RPM or to idle for descent
When should carb heating not be used and why?
- When maximum power is required such as in TKOF and go-around etc
- This is because warm air in the fuel/air mixture reduces fuel efficiency and therefore power
Why is a propeller twisted?
To create equal thrust across the propeller
What is blade pitch with regards to propellers?
- The angle made by the chord of the blade and its plane of rotation
- When the angle is great, the propeller is said to have coarse pitch - ACFT will move father forward in one rotation than a fine pitch
- __________ pitch propeller is best for climbing
- __________ pitch propeller is best for speed at cruising altitude
- __________ pitch propeller is fixed and gives efficiency over a range of power settings
- Fine
- Coarse
- Standard
N.B. Three types of fixed pitch propellers
What is a variable pitch propeller?
AKA constant speed propeller - enables the pilot to change the pitch of the propeller to suit differing requirements
N.B. Done automatically in some modern ACFT
With regards to variable pitch propellers, what is feathering?
Rotating propeller blades so they are parallel to the airflow. It reduces drag if the engine fails or is deliberately shut down
N.B. Some constant speed propellers have the ability to change to a reverse pitch angle, generating reverse thrust and reduces landing run and wear on tyres and brakes
How does the number of blades affect the power of the engine?
Enables it to be absorbed more efficiently - thrust from the engine is delivered to larger surface area without increasing the diameter of the propeller disk
What are the advantages of the piston engine and propeller? (5)
- Simpler design reduces manufacturing and maintenance cost
- More efficient at low speeds and low altitude
- Faster initial acceleration than jet engine
- Immediate reaction to pilot input
- Propwash over wings generates lift at low speeds, which reduces take-off run and aids controllability
What are the disadvantages of the piston engine and propeller?
- Power output is limited
N.B. Theoretically, the larger the propeller, the more thrust is generated. However, as the tips reach supersonic speed, their aerodynamic efficiency decreases and noise increases significantly
- A propeller accelerates a __________volume of air by a __________ amount
- A jet engine accelerates a __________ volume of air by a __________ amount
- Large, small
- Small, large
What is Newton’s second law?
Force = Mass x Acceleration (F=MA)
N.B. The amount of power an ACFT produces (F) is determined by how much air (M) it can accelerate, and by how much (A)
What are the basic stages of a jet engine?
- Air Intake - Collects and directs air into the compressor. Simple design or variable geometry
- Compressor Stage(s) - Compresses air by many factors, depending on type of compressor and the number of stages of compression
- Combustion Chamber(s) - Highly compressed air is mixed with fuel and burnt
- Turbine Stage(s) - Extracts some energy from large volume of air leaving the combustion stage to drive the compressor(s)
- Exhaust - Accelerates the air leaving the turbine stage. Civilian types are also designed to attenuate noise
N.B. The pressure energy of the air is raised, followed by the addition of heat energy, before conversion to kinetic energy in the form of a high velocity Jet
Types of jet engine (7)
- Turbojet
- Low Bypass Turbofan
- High Bypass Turbofan
- Turboprop
- Ramjet
- Scramjet
- Turboshaft (Helicopters)
What are the 2 types of basic jet engine?
- Centrifugal flow compressor
- Axial flow compressor
What is a Centrifugal Flow Compressor?
A type of basic jet engine which uses an impeller to accelerate air and a diffuser to produce the required pressure rise
What is an axial flow compressor?
A type of basic jet engine which employs alternate rows of rotating rotor blades to accelerate the air and stationary stator vanes to diffuse the air until required pressure is obtained
What is a turbofan bypass engine and why was it developed?
A type of jet engine which draws air both through and around the core. This increases fuel efficiency and reduces noise considerably. Can be high or low bypass
How do afterburners work?
- A potential additional 70% thrust can be generated by injecting fuel directly into the hot exhaust gas stream. The fuel combusts
- Very fuel inefficient and extremely noisy
- Normally only used by military ACFT on TKOF and when transitioning to supersonic flight
- Can be used in axial flow and low bypass turbofan engines
What are the advantages and disadvantages of the turbofan engine?
Advantages
- Efficient - power derived from 2 sources, core & fan
- Significantly more powerful than piston engines (80 000 lbs thrust)
- Higher speed achievable
- Afterburner can be used for additional thrust
Disadvantages
- Complex design & manufacture results in high cost
(2020 cost for Rolls Royce Trent 1000 engine circa $40M including support) - Response to pilot input slow – ‘spool up’ time required to generate power
What is a turboprop engine?
A jet engine which drives a propeller with a turbine at the back - turbine at the back is turned by hot exhaust
What are the advantages of a turboprop engine?
- In dense air, i.e. lower levels, a propeller has a higher efficiency than jet exhaust
- Generally, turboprop aircraft can operate from shorter runways than jets
- The propeller can be ‘feathered’ to minimize drag in the event of engine failure
- Mechanical reliability improves due to relatively few moving parts
- Light weight
What are the disadvantages of the turboprop engine? (4)
- Propellers lose efficiency at high altitudes
- Vibration and noise levels can cause passenger discomfort
- Lower cruising levels can be susceptible to icing and turbulence
- Lower cruising speeds can cause sequencing problems for ATC when mixed with jet operations
Examples of ground incidents?
- Abnormal start
- Emergency engine shutdown on deck
- Loss of brakes
- Hot brakes
- Brake fire
- Jammed controls on deck
- Taxi mishap
Examples of TKOF emergencies?
- Aborting Takeoff
- Engine Failure During Takeoff
- Engine Failure After Takeoff
- Tyre Failure
- Abnormal Takeoffs
Examples of in flight emergencies?
- Engine Failure
- Hydraulic System Failure
- Electrical System Failure
- Environmental System failure
- In-Flight Fire
- Smoke/Fire of Unknown Origin
- Oil/Fuel System Failure
- Fuel Leaks
- Pitot Emergency Static Air Source
- Loss of pressurisation/Explosive decompression
- In-flight damage
What is the general format do pilots follow when reassessing a situation?
D - Diagnose the problem
O - Options available
D - Decide what to do
A - Allocate tasks
R - Review
What are the 6 primary flight instruments and how are they categorised?
Statit/pitot-static
- Altimeter
- Vertical Speed Indicator (VSI)
- Air Speed Indicator (ASI)
Gyroscopic
- Artificial Horizon/Attitude indicator
- Heading Indicator/Gyrosyn compass
- Turn coordinator
N.B. Modern flight decks and even some light ACFT incorporate data from the above into a Primary Flight Display (PFD)
How is atmospheric pressure which feeds flight instruments sensed?
- Via the pitot system. Pressure is measured statically and dynamically
- Static air - is not in direct flow of air over the ACFT in flight
- Dynamic air - is that which is encountered when the ACFT is moving forwards
N.B. Pitot systems are often duplicated or triplicated for redundancy
What is an altimeter and errors associated with it?
- An instrument used to measure the altitude of an ACFT above a fixed level (depends the pressure setting set on the sub scale)
- Correct sub scale setting is vital to ensure the altimeter reads correctly; Setting higher pressure will cause altimeter to over read; Setting lower pressure will cause altimeter to underread
- Altimeter calibrated to ISA so if local pressure and temperature gradients don’t follow ISA, errors could occur
- Environmental errors can be disregarded by ATC as altimeters in close proximity are likely to react in the same way, therefore separation will be unaffected
What is a vertical speed indicator?
Uses static pressure to show the rate of climb or descent in feet per minute
N.B. There is always a slight lag in the instrument. Between 6-9 seconds of steady climb, descent or level flight must elapse before accurate reading is displayed
What is an airspeed indicator?
Measures the difference between static pressure and dynamic pressure received from the pitot tube. Indicates speed at which ACFT is moving through the air
What do the following speeds mean displayed on an ASI?
1. White = V(f) = __________
2. Green = V(no) = _________
3. Yellow = V(o) = __________
4. Red = V(ne) = __________
- Flap operating speed range
- Normal operating speeds
- Max. Manoeuvring speed
- Never exceed speed
What errors are associated with ASI?
- Instrument error - small imperfections in instrument
- Position error - error when pitot tube is not pointing directly into the airflow
- Density error - less air pressure at altitude
- Compression error - If TAS exceeds about 300kts, air entering pitot tube compressed over the pitot hole causing the ASI to over-read - can be corrected
ASI errors should not exceed 3% or 5kt
Pitot system blockages - ASI issues
1. What happens when there is a static blockage?
2. What happens when there is a pitot blockage?
- Pressure in instrument case will remain the same. As long as external pressure stays the same, ASI will read correctly i.e. when maintaining constant height. ASI will under read when climbing
- If pitot line is blocked, true changes in airspeed will not be shown. Same altitude would been airspeed would read the same regardless of any change in speed. In descent, rising static pressure will cause ASI reading to decrease. Vice versa in climb
Why do we used Mach numbers for speeds at high altitude?
To overcome the problem in difference between indicated airspeed and true airspeed at high altitudes
N.B. At 30,000ft, the TAS is more than 50% higher than the IAS
What errors are associated with a Mach meter?
Instrument and pressure error
N.B. Incidentally, these errors are very small so indicated Mach number can be taken to be the true Mach number
What are 2 of the most important properties of a gyroscope?
Inertia and precession
What is an artificial horizon/attitude indicator?
A gyroscopic instrument which employs gyros property of inertia to indicate pitch and roll of the ACFT relative to the Earths horizon
What is a turn and slip coordinator?
A gyroscopic instrument that works on the principle of precession. Indicates the ACFTs turn and also adverse yaw to be corrected with rudder
What is a heading indicator?
AKA Direction Indicator (DI) or gyrosyn compass. A gyroscopic instrument which is tied to the vertical/yaw axis of an ACFT to indicate ACFTs heading on a rotating compass card
N.B. Must be aligned with ACFTs compass when in straight and level unaccelerated flight
What sort of error is a magnetic compass subject to?
- Deviation error - compass affected by ACFT electrical equipment and by ferrous metallic components in the ACFT. Compass correction card
- Dip error - Needle dipping towards pole at high latitudes
- Acceleration error - occurs during airspeed changes and is most apparent on headings of east and west. Accelerating North, Decelerate South ANDS
Why can ACFT brakes get hot while taxiing?
- Engines of modern jet transports have a very high residual thrust
- Braking often required to keep ACFT at a safe speed
- Long taxi routes can mean hot brakes
- Hot brakes are not 100% efficient meaning that an ACFT aborting TKOF with very hot brakes may not be able to stop. Possibility of tyre burst as well
What can a pilot do to cool brakes after TKOF?
Pilot may decide to leave the undercarriage down to cool the brakes. Do not automatically assume he has forgotten to raise it
Why do pilots of jet ACFT like to climb as soon as possible?
Jet engines are not efficient at low levels. Higher fuel burn and is more noisy
What should ATC do when a pilot calls top of descent and why?
ATC should always try to comply with pilots request for descent because they do not like to descend too early (due to fuel) or too late (too much to do in a short space of time)
What are the most frequent things that pilot complain about to ATC?
Economics - 2 frequent complaints
- Long routings at low level
- ATC applies poor speed control when they are in the landing configuration, with wheels and flaps down - high drag in this configuration and therefore high fuel consumption
Ecological
Noise and pollution are serious consequences of the long, low, high drag, high power approach to landing
State the possible consequences of hydraulic failure for approach and landing
An ACFT with a hydraulic failure may have any or all of the following problems; Flaps, Brakes, Gear down, Rudder, Aileron problems
Flaps - A lower angle, faster approach and touch down speed potentially needing full runway length
Steering - ACFT ay stop on RWY and require tug/bus. RWY blocked
Weather - Cross winds, wind shear and fog all make landing difficult
What factors affect TKOF performance?
- TAKE-OFF MASS. (Load + ACFT weight)
- POWER. Provided by Powerplant
- ELEVATION OF AIRFIELD. (Air Pressure calculations based on 1013.2mbs)
- RWY. Length/Slope/Constr/Contam
- AIR TEMPERATURE (ICAO Std. 15o C)
- WIND. Strength & Direction
- NOISE ABATEMENT & ATC
- COMPANY INSTRUCTIONS
- SERVICABILITY
What factors affect performance during the climb? (6)
- MASS. (Load + ACFT weight)
- SPEED
- WIND. Strength & Direction
- CABIN PRESSURISATION
- AIR TEMPERATURE (ICAO Std. 15ºC)
- AIR DENSITY
What factors affect performance during cruise?
- MASS. (Load + ACFT weight)
- CRUISING SPEED
- WIND. Strength & Direction
- CABIN PRESSURISATION
- LEVEL
What factors affect landing performance?
- LANDING MASS (Load + ACFT weight)
- ELEVATION OF AIRFIELD (Air Pressure calculations based on 1013.2hPa
- RWY- Length/Slope/Construction/Contamination
- AIR TEMPERATURE (ICAO Std. 15°C)
- WIND. Strength & Direction
- ATC (Request to vacate early, etc)
- COMPANY INSTRUCTIONS
- PILOT PREFERENCES
- AIRCRAFT CONFIGURATION
What economic consequences to an ACFT due to ATC changes to flight profile should we be aware off?
- Routing - Extra track distance costs time and money
- Flight Level - Higher levels allow better fuel economy
- Speed - As close to Mcrit as possible to allow efficiency. On approach, slow speeds need engine power and flap high speeds burn fuel but reduce time
- Rates of Climb/Descent – High climb rates burn lots of fuel. Slow descent rates need engine power and flaps
- Holding– all of the above fuel, time, drag, track etc.
What factors affect holding of ACFT?
In addition to economic consequences i.e. Fuel, time, drag, track, etc:
- Speed at which the ACFT can hold
- Level at which they are holding.
- The higher the level the more fuel efficient
- Any turbulence that may require a higher holding speed
What are the 4 types of helicopter tail rotor?
- Bladed system
- Fenestron
- NOTAR
- No system
What is V(1)?
The speed beyond which the TKOF can no longer be safely aborted
What is V(R)?
Rotate speed. The speed at which the ACFTs nose wheel leaves the ground
What is V(LO)?
Maximum landing gear operating speed
What is V(2)?
TKOF safety speed. The speed at which the ACFT may safely become airborne with one engine inoperative
What is V(NE)
Velocity never exceed
What is V(REF)?
Landing reference speed
What is the flight envelope?
Represents the strict limits of ACFT performance. I.e. predictable behaviour. Max/min/stall speed. Ceiling, Critical Angle of Attack, Maximum Rate of Climb
What are the most common aviation fuels?
- AVGAS (aka 100LL) - highly refined from of kerosene for use in piston engines
- Jet A1 - Unleaded kerosene - powers modern commercial airliners
- Jet B - Naptha-kerosene blend for cold weather performance - dangerous to handle
- CNG and LPG also developed for use in ACFT but this has not neem incorporated
What are the principle threats to effective in-flight fuel management and what three categories do the effects of this fall into?
Threats
- Complacency, failure to comply with company policy and intentional deviation from planned flight profile
Effects categories
- Operational, legal and financial
What are oil temperature and pressure gauges?
Instruments vital for the safe operation of the engine. Lack of oil can seriously affect engine bearings and could result in engine failure if not corrected. High oil temperature may indicate that the oil levels are dangerously low
What are temperature gauges?
Measure engine temperature and RPM. Should be monitored - falling RPM could indicate loss of power. High temperature could indicate a failure of the cooling system
What is GPWS?
Ground proximity warning system or TAWS. Used to help prevent Controlled Flight Into Terrain (CFIT). Uses radar altimeter to determine height above terrain immediately below ACFT. Audible alarm in cockpit
What is EGPWS?
Enhanced Ground Proximity Warning System - Also known as Terrain Awareness and Warning System. Also includes forward looking terrain avoidance
TAWS Alerts are __________
TAWS Warnings are __________
- Soft - Unusual situation but not yet critical
- Hard - Indicate a critical situation
What should ATCOs be aware of when an ACFT carries out a TAWS missed approach?
ACFT may not conform to published missed approach procedure. When controller informed, they should confirm altimeter setting and not dissuade pilot from climbing
Why does a pilot need weather radar?
In order to avoid flying into areas of bad weather. Pilots able to take their own avoiding action or if under ATC control, can request permission to deviate from track
What is the purpose of autopilot?
A system which can fly the ACFT on behalf of the pilot. Pilots may select cruise mode with speed/Mach No. lock, height lock, climb and descent rates, turns etc including full automatic landings
What are some advantages of autopilot?
- Reduces pilot workload
- Ensures accuracy
- Many factors can be considered
- Reduces input errors (CPDLC - Data link)
What is the FMS and how does it assist the pilot?
Flight Management System
A database which integrates route planning and airport data with engine management and autopilot for flight optimisation. Coupled with autopilot, it can plan, navigate and fly a selected route from just after TKOF to an automatic landing at destination
What is EFIS?
Electronic Flight Instrument System
Glass cockpit. Primary flight display. Combines 6 instruments and TCAS warnings and navigation mode
N.B. Full set of mechanical flight instruments are provided as a back up in the event of EFIS failure
What is EGT in a jet engine?
Exhaust gas temperature - it must be carefully controlled to prevent overheating of exhaust system with consequent risk of fire
What vital ACFT systems usually rely on hydraulic power?
Control surfaces, wheel brakes, nose wheel steering
How are ACFT classified?
What are the ICAO wake turbulence categories?
Super (J) - A380-800
Heavy (H) - 136,000kg or greater
Medium (M) - More than 7000kg but less than 136,000kg
Light (L) - 7000kg or less
How do group designators on which wake turbulence separation is based on distinguish ACFT?
ACFT weight and wingspan
What are the ACFT Categories? (Velocity at Threshold)
- Cat A = Less than 91 knots IAS
- Cat B = 91 to 120 knots IAS
- Cat C = 121 to 140 knots IAS
- Cat D = 141 to 165 knots IAS
- Cat E = 166 to 210 knots IAS
N.B. For purposes of instrument approaches and obstacle clearance criteria, ACFT categorised by velocity at threshold which is defined as 1.3 x the stalling speed in landing configuration at maximum certificated landing mass
What is the most significant cause of adverse community reaction in relation to operation and expansion of airports?
ACFT Noise
What is a continuous descent approach?
Arriving ACFT descends from an optimal position using minimum thrust and avoids level flight to the extent permitted by the safe operation of the ACFT and compliance with published procedures and ATC instructions
What are the benefits of continuous descent approaches?
- Allows for smooth constant angle descent to landing
- Reduces fuel burn
- Reduces ACFT noise
