JCAA PPL Theory flashcards

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

Transition altitude

The altitude at or below which the altimeter is set to the local QNH; above it the standard pressure 1013.25 hPa is set, and the layer between transition altitude and transition level is the transition layer.

Special VFR clearance

An ATC clearance allowing flight in controlled airspace below VMC minima, requested by the pilot, requiring clear of cloud and at least 1 statute mile visibility by day, with see-and-avoid responsibility retained.

Right of way on approach

An aircraft on final approach to land has right of way over other aircraft in flight; a lower aircraft has right of way over a higher one, except it must not cut in front of an aircraft on final.

Squawk 7600

The transponder code selected after a radio communication failure; the pilot then follows the published communication failure procedures and continues according to the last acknowledged clearance.

Stoichiometric mixture

The air/fuel mass ratio of about 15:1 at which all fuel and oxygen are consumed; richer mixtures cool the engine, leaner mixtures give better economy but risk detonation if too lean.

Carburettor icing conditions

Most likely with outside air temperature between about -7 °C and +21 °C and high relative humidity; carburettor heat melts the ice but first causes a temporary further drop in power.

Detonation

Uncontrolled explosive combustion of the fuel charge after normal ignition, caused by excessive manifold pressure, high cylinder head temperature or an over-lean mixture; it can damage the engine quickly.

Blocked static source

A blocked static port affects the airspeed indicator, altimeter and vertical speed indicator; the altimeter freezes at the altitude where the blockage occurred and the airspeed reads incorrectly.

Magnetic compass errors

Deviation from aircraft magnetic fields, plus turning error and acceleration error; the compass is reliable only in straight, level, unaccelerated flight, so it is used to cross-check the heading indicator.

Density altitude

Pressure altitude corrected for non-standard temperature; it rises with high elevation, high temperature and low pressure and degrades take-off, climb and landing performance.

Crosswind component

The component of wind at right angles to the runway, calculated as wind speed multiplied by the sine of the angle between wind and runway; it must not exceed the aircraft limit.

Centre of gravity calculation

Total moment divided by total weight, where each moment is weight multiplied by its arm; the result must lie within the forward and aft limits for take-off, flight and landing.

Final reserve fuel

Fuel that must remain at landing, typically 30 minutes at holding speed for VFR flight; it is added to trip, taxi, contingency and alternate fuel when planning.

Aft centre of gravity effect

An aft CG reduces longitudinal stability and stick force, lowers stall speed slightly but makes stall and spin recovery harder, and shortens take-off distance.

Best glide speed

The speed giving maximum range in a power-off descent, close to the speed for best lift/drag ratio; a headwind raises the speed for maximum range and a tailwind lowers it.

Time of useful consciousness

The period before hypoxia impairs judgement and control, roughly 3 to 5 minutes at 25,000 ft and 30 to 60 seconds at 35,000 ft without supplemental oxygen.

Hyperventilation

Excessive breathing that lowers blood CO2 and causes dizziness, tingling and cramp; slowing the breathing rate or breathing into a bag relieves it, whereas hypoxia requires oxygen.

The leans illusion

A vestibular illusion in which a slow roll into a bank is not sensed, so the pilot believes the aircraft is level and may lean in the wrong direction when correcting.

Dark adaptation

The eye's adjustment to low light, taking about 30 minutes and relying on rods; bright light, smoking and low oxygen all degrade it, so red light is used in the cockpit.

Alcohol and flight

Even small amounts of alcohol impair judgement and reaction time; the standard rule is no alcohol within 8 hours of flight and blood alcohol below the legal limit.

QNH versus QFE

QNH is the pressure reduced to sea level, so the altimeter reads elevation on the ground; QFE is the pressure at the aerodrome, so the altimeter reads zero on the ground.

Temperature-dew point spread

The difference between temperature and dew point; a spread of 2 °C or less indicates air close to saturation, favouring fog, low cloud and carburettor icing.

Structural icing range

Ice forms where visible moisture exists at temperatures between 0 °C and about -20 °C; it adds weight, increases drag and stall speed, and reduces lift.

High to low altimeter error

Flying from an area of high pressure to low pressure without resetting the altimeter makes the aircraft lower than the altimeter indicates, so terrain clearance is reduced.

SIGMET

A warning of significant weather such as thunderstorms, severe turbulence, severe icing or volcanic ash that may affect the safety of aircraft in flight.

1 in 60 rule

A track error of 1 nautical mile after 60 nautical miles flown corresponds to 1 degree of angular error; it is used to estimate the heading correction needed.

Magnetic variation

The angle between true north and magnetic north at a location; east variation is subtracted from true heading to obtain magnetic heading, west variation is added.

VOR radial tracking

A VOR radial is the magnetic bearing from the station; to fly inbound, set the OBS to the reciprocal of the radial and track it with a 'to' indication.

RAIM

Receiver autonomous integrity monitoring, a GPS function that checks whether the position solution can be trusted; loss of RAIM means the pilot must revert to other navigation means.

Wake turbulence avoidance

Vortices are strongest from heavy, clean, slow aircraft and sink below the flight path; stay above and upwind and land beyond the preceding aircraft's touchdown point.

Rejected take-off decision

Before a set speed, close the throttles, apply maximum braking and maintain directional control; above that speed, the safer option may be to continue and climb.

Load factor in a turn

In a level turn the load factor equals 1 divided by the cosine of the bank angle; a 60-degree bank doubles the load and raises stall speed by about 41 percent.