Mauritius DCA IR Theory flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Semicircular rule

Cruising level rule by magnetic track: 000–179 degrees uses odd thousands, 180–359 uses even thousands, to give vertical separation between opposite-direction IFR traffic.

Readback requirement

Pilot must repeat clearances, level, heading and speed instructions, altimeter settings and frequencies; the readback confirms the instruction was correctly received and understood.

Lost communication squawk

Squawk 7600 when radio contact is lost; maintain the last assigned route and level, then follow the published lost-communication procedure.

Minimum fuel declaration

An advisory to ATC that the flight may land with less than final reserve fuel; it is not an emergency and does not give priority, unlike MAYDAY FUEL.

Blocked pitot tube

With the static port clear, the airspeed indicator behaves like an altimeter: it reads higher in climb and lower in descent because trapped pressure stays constant.

Blocked static port

Airspeed over-reads in climb and under-reads in descent; altitude freezes at the blockage value; the alternate static source restores operation with small errors.

Turn coordinator role

Electrically driven rate instrument that shows rate of turn and roll; it survives loss of the vacuum system and allows partial-panel instrument flight.

Standby attitude indicator

Independent gyro instrument with its own power supply; it must be uncaged and checked for correct erection before flight and during cruise.

Density altitude formula

Density altitude = pressure altitude + 120 x (OAT - ISA temperature). It drives take-off, climb and landing performance and is higher than pressure altitude on hot days.

Net take-off flight path

The gross climb gradient reduced by 0.8 percent for twins, 0.9 for three engines and 1.0 for four engines, giving the gradient used for obstacle clearance.

Final reserve fuel

Fuel to hold for 30 minutes at 1500 ft above the aerodrome in ISA conditions; it is part of the required fuel and must not be planned for use.

Aft CG effect

Centre of gravity behind the aft limit reduces longitudinal static stability, lightens control forces and can cause pitch-up and difficulty recovering from a stall.

Time of useful consciousness

The period before hypoxia incapacitates; approximately 30 to 60 seconds at FL350 and longer at lower altitudes, shortened by exertion or cold.

Somatogravic illusion

A false pitch sensation caused by linear acceleration: acceleration feels like pitch-up and deceleration like pitch-down, which can lead to inappropriate control input.

Leans illusion

After a sustained bank, a sudden return to level flight feels like a bank in the opposite direction, so the pilot may lean into a bank that no longer exists.

Circadian low

Periods of lowest alertness around 0300–0600 and 1500–1700 local time; fatigue effects are greatest then and during long duty periods.

QNH versus QFE

QNH set on the subscale gives altitude above mean sea level; QFE gives height above the aerodrome reference point and reads zero on the ground.

BECMG versus TEMPO

In a TAF, BECMG indicates a gradual lasting change over a period, while TEMPO indicates temporary fluctuations that do not persist for the whole period.

Freezing rain hazard

Supercooled water droplets freeze on impact and can produce rapid, severe airframe icing; it is a strong reason to divert or change level.

Wind shear response

A sudden airspeed loss or sink increase on approach should trigger a go-around; chasing the glideslope after a shear encounter risks a hard landing or stall.

VOR course deviation

One degree of CDI deviation equals about 1 NM per 60 NM from the station; TO/FROM depends on the selected OBS course relative to the station.

ADF bearing formula

Bearing to the station = aircraft heading + relative bearing shown on the ADF needle; the result is a magnetic bearing to the station.

Glideslope frequency band

The ILS glideslope is transmitted in the UHF band, separate from the VHF localiser, so a dedicated glideslope receiver is required.

RAIM prediction

Receiver autonomous integrity monitoring checks whether enough satellites are available to assure navigation integrity; a positive prediction is required before an RNP approach.

Climb via SID

A clearance phrase meaning the published SID altitude restrictions apply; 'climb and maintain' instead cancels the published restrictions.

Stabilised approach criteria

By 1000 ft in IMC the aircraft must be on speed, on profile, on centreline, with thrust set and checklist complete; otherwise a go-around is flown.

Decision altitude

The altitude on a precision approach at which a missed approach must be initiated if the required visual reference is not established; it is referenced to the altimeter.

Missed approach point

The point on a non-precision approach where the missed approach must begin if visual reference is not established; the aircraft may level at MDA until then.

Load factor in turns

Load factor n = 1/cos(bank angle); at 60 degrees bank it is 2 g, so stall speed rises to 1.41 times the 1 g stall speed.

Induced drag relationship

Induced drag is proportional to the square of the lift coefficient and inversely proportional to the square of speed; it dominates at low speed and high angle of attack.

Critical angle of attack

The angle of attack at which lift coefficient is maximum; exceeding it causes a stall regardless of airspeed, attitude or weight.

Mach number definition

Mach number is true airspeed divided by the local speed of sound; the speed of sound falls with temperature, so a constant TAS gives a higher Mach at altitude.