Aircraft Flashcards
What is an Attitude Indicator and how does it work?
The Attitude Indicator is a gyroscopic instrument that shows the aircrafts Angle of Bank and Pitch.
Together with other instruments it allows the pilot to fly without external reference (at night, in cloud, over an expanse of water with no horizon in view).
A gyro is a rapidly rotating wheel (normally anti-clockwise,9-12,000rpm) which creates a centrifugal force. This force makes the wheel resistant to movement. The gyro wheel is suspended in 2 gimbals, and weighted at the bottom with a pendulum which keeps the gyro perpendicular to the earth, regardless of the manoeuvring of the aircraft.
The gyros rotation is maintained by either:
- A suction pump or create airflow over the gyro disc which has notches or ‘buckets’ around its circumference (‘water wheel’ effect). Mainly used in lighter aircraft, or
- Using an electric motor.
Failure of either system will freeze the display or give erroneous readings- electrical failure ‘flags’ or pump information is therefore also provided.
What does the Airspeed Indicator show and how is it measured?
The Airspeed Indicator provides the pilot with airspeed information in knots- called Indicated Airspeed. Different colour bands draw the pilots attention to various airframe limitations, for example a band might show the range at which the aircrafts flaps can be used.
The Pitot tube protrudes from the aircraft in the direction of airflow to sense Static and Dynamic Pressure. Static Pressure is removed from Pitot Pressure by means of a Static Vent, and Dynamic Pressure is displayed on the A.S.I.
The Pitot tube can become blocked by detritus or ice, especially at high altitudes, so they are often heated. On larger aircraft multiple redundancy will be achieved by utilising 2 Pitot tubes- one on each side of the aircraft.
What does an Altimeter measure and how does it work?
An Altimeter provides the pilot with ‘level’ information which is measured in feet (in the Europe).
Altimeters are a sealed unit with only one input- a Static Vent. As Static Pressure reduces the sealed capsule expands. The opposite is also true. The smallest of expansions and contractions are measured, geared and then displayed on the Altimeter. The datum pressure of the sealed capsule is adjusted on the altimeter by rotating a nob (set for QNH, QFE, SAS).
What is a Vertical Speed Indicator (V.S.I.) and how does it work?
A Vertical Speed Indicator displays the rate at which an aircraft climbs or descends and is measured in feet per minute.
Inside the V.S.I. a sealed capsule expands and contracts as Static Pressure changes. The capsule has one small calibrated hole or vent, which allows air pressure to EVENTUALLY equalise inside and outside the capsule. (Hence the measurement is of the pressure in relation to what it was recently- rate of change).
What is the Turn and Slip Indicator and how does it work?
The ‘Turn Indicator’ is a gyroscopic instrument (specifically a Rate gyro), which shows direction and rate of turn. It is tied to the longitudinal axis of the aircraft in order to sense movement around the aircrafts normal axis, i.e. Yaw.
It is displayed as a Rate of Turn:
Rate 1= 3°/second (360° in 2 minutes) This is the normal rate of turn in a passenger aircraft.
Rate 2= 6°/second (360° in 1 minute)
Rate 3= 12°/second (360° in 30 seconds).
The Slip Indicator senses gravity. The indicator is a ball which is suspended in a viscous fluid which indicated whether or not the aircraft is in balanced flight. The pilot will apply rudder to yaw the aircraft back into balance if necessary.
What is a Direction Indicator (D.I.), and how is it better than a compass?
A Direction Indicator is a gyroscopic instrument strapped to the aircrafts horizontal plane. It displays heading, similarly to a compass, but is free from possible compass errors caused by turning and acceleration.
What is Limited or Partial Panel flying?
Flying without an Attitude Indicator and/or a Direction Indicator. It requires considerable concentration by the pilot as accurate headings will be hard to fly, especially as erroneous information may be hard to cover up and ignore.
What are the main Flight Instruments used in an aircraft?
Attitude Indicator Airspeed Indicator Altimeter Vertical Speed Indicator Turn and Slip Indicator Compass Direction Indicator
What factors affect aircraft during take-off? (4 points)
Runway conditions:
- Slope: Increased take-off run needed for upslope, and vice-versa.
- Length: Longer runways allow greater time/distance to reach critical take-off speeds.
- Surface: Non- hard/smooth surface increases ground roll (friction). Mud, snow or standing water reduces acceleration (traction).
Wind:
- Taking off into headwind is usual, take-off velocity at lower speeds allows shorter take-off runs.
Air Density
- Increased density means a higher take-off velocity is required, and less thrust is available.
Aircraft Weight:
- Increasing gross weight of aircraft means that required take-off velocity is required, more mass to accelerate along the runway and more rolling friction.
What factors affect an aircraft during the Climb? (3 points)
Aircraft Weight:
- Change in weight of aircraft means drag increases a more power required. This affects both the climb angle and rate of climb.
- Max rate of climb will reduce, aircraft must be operated at higher climb speed.
Altitude:
- Increase in altitude will increase the power required AND decrease the power available. Therefore, climb performance of an aircraft diminishes with altitude.
Wind, Temperature and Air Density:
- Strong headwinds provide more lift, and faster rate of climb.
- Air at higher temperatures holds more moisture resulting in reduced air density. Less dense air reduces climb performance.
What factors affect an aircraft during cruise?
Cabin Pressurisation:
- Not all aircraft equipped with cabin pressurisation, those without will climb at a slower rate and be limited to a lower level.
Aircraft Weight, Speed and Altitude:
- Once in cruise (balanced flight) the weight of the aircraft will reduce as fuel consumed. Optimum airspeed and power setting may decrease, optimum cruising altitude may increase.
Wind and Temperature:
- Headwinds slow an aircraft down, cause higher fuel consumption. May result in request of level change.
- Temperature may increase the formation of ice, which adds weight and drag. May result in lower level requested.
What factors affect aircraft in Descent?
Aircraft Weight:
- Weight reduced as fuel consumed, aircraft may be too heavy for landing and require additional routing or holding to burn off excess fuel.
Speed and Rates of Descent:
- Aircraft may be instructed to maintain certain speeds by ATC, this can affect rates of descent.
Aircraft Configuration:
- Usually aircraft flown in ‘clean configuration’, i.e. no flaps, air brakes, landing gear etc. for as long as possible- more streamlined.
Wind:
- Changing wind conditions can cause turbulence and induce drift.
Cabin Pressurisation:
- Normal descents possible provided cabin pressurisation equipment fully functional, otherwise aircraft must descend quickly.
What factors affect aircraft during final descent and landing?
Aircraft Configuration:
- Flaps, slats and air brakes deployed to slow the aircraft whilst maintaining lift.
Weight:
- Main factor in determining landing distance. Increased weight will result in the need for increased speed to support aircraft at landing angle of attack.
Wind:
- Strong wind increases likelihood of turbulence and wind shear on final approach.
- Headwinds affect ground speed and therefor landing run.
Air Density:
- Increase in density will have the effect of increasing the landing speed.
NB. The most critical conditions of landing are a combination of high gross weight, high density altitude and unfavourable wind.
What is minimum dynamic hydroplaning speed, and why is it important?
9 x (square root of) tyre pressure (in PSI).
Water on the runway reduces the friction between tyre and ground and can reduce braking effectiveness.
The ability to brake can be completely lost when the tyre is hydroplaning because a layer of water separated the tyre from the runway surface. Braking and directional control can be almost nil.
What could be the economic consequences of changes to the flight profiles of aircraft?
- Rerouting could involve longer distances flown and therefor more fuel burn and associated costs.
- Aircraft burn less fuel at higher altitudes, so lower flight levels than planned can lead to more fuel burn and higher CO2 pollution.
What Ecological factors affect airline performance, and what rules are applied?
Fuel Jettisoning- Over the sea if at all possible, or above 10000ft. If this is not possible, may be carried out above 7000ft agl in winter and 4000ft agl in summer. Fuel may only be jettisoned below this level if the situation is unavoidable (emergency).
Noise Abatement Procedures- Procedures in place to minimise localised disturbance. May include: requiring departing aircraft to fly a specific heading or maintain a track to a specified distance and/or altitude, use of Continuos Descent Approaches (CDAs), reminding aircraft operators to fly aircraft in such a manner as to reduce the impact to local residents.
How does aviation affect the environment?
- Aviation contributes to approximately 2-3% of global CO2 emissions.
- Water pollution
What are the types and uses of Direction Finding equipment?
Automatic Direction Finding equipment obtains a bearing to NDBs. The Radio Magnetic Indicator displays the Magnetic bearing of the beacon FROM the aircraft. Requires situational and wind awareness (drift etc.).
ADF can be used to make a ‘Non-precision Approach’ (NDB approach, no vertical guidance).
