NZ CAA PPL Navigation flashcards

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

True airspeed formula

TAS ≈ CAS × (1 + 0.02 × pressure altitude in thousands of feet). At 10,000 ft, 100 kt CAS gives approximately 120 kt TAS.

Density altitude

Pressure altitude corrected for non-standard temperature. It rises about 120 ft per 1 °C above ISA and increases takeoff and climb distances.

Fuel reserve requirement

For VFR in NZ, plan trip fuel plus contingency, alternate fuel where required, and a 30-minute final reserve. Compare total against usable fuel, not tank capacity.

Wind correction angle

The angle between heading and track needed to counter drift. sin(WCA) = (wind speed × sin(wind angle to track)) / TAS.

Ground speed calculation

GS = TAS × cos(WCA) − wind speed × cos(wind angle to track). A direct headwind reduces GS by the full wind component.

Alternate aerodrome rule

The alternate must be forecast to permit a landing in VMC (for VFR) or above approach minima at the ETA, with fuel to reach it plus final reserve.

Centre of gravity calculation

CG is found from total moment divided by total weight. Confirm it lies inside forward and aft limits for takeoff, zero-fuel, and landing configurations.

Dead reckoning position

Estimated position from the last fix, using heading, TAS, elapsed time, and wind correction. Update at least every 30 minutes or at each turning point.

Time en route

Time = distance / ground speed. At 120 kt GS, 45 NM takes 22.5 minutes. Convert minutes to decimal hours before multiplying by fuel flow.

Fuel used calculation

Fuel used = fuel flow × time in hours. A 40 L/h flow over 1.5 hours consumes 60 L.

Mental DR speeds

At 60 kt you cover 1 NM per minute; 120 kt gives 2 NM/min; 180 kt gives 3 NM/min. Scale linearly for other speeds.

Drift definition

The difference between heading and actual track. If the planned wind correction angle was correct, drift is zero.

Revised heading after fix

New heading = old heading + track error + closing angle to destination. Compute each component with the 1 in 60 rule.

Top of descent rule

Plan about 3 NM per 1,000 ft of altitude to lose at a 3° profile. At 6,000 ft, start descent about 18 NM out.

NZ chart scales

On 1:250,000 charts, 1 cm equals 2.5 km. On 1:500,000 charts, 1 cm equals 5 km. Use the scale bar for quick distance checks.

Grid reference order

Read eastings first, then northings: "along the corridor, up the stairs". Read to the nearest tenth of a grid square for precision.

Contour interval NZ charts

On NZ 1:50,000 topographical charts the contour interval is typically 20 m. Closer contours indicate steeper terrain and stronger mechanical turbulence.

Track crawling technique

Select two or three prominent features on or near track, such as lakes or road junctions, and time the legs between them.

Magnetic variation NZ

Magnetic variation in NZ is about 20–25° east. Apply variation to convert true to magnetic: "east is least" when converting.

Two-line position fix

A fix using two features that cross, such as a road and a river. Confirm with a third cue or a navaid radial where possible.

VOR radial interpretation

The VOR bearing is magnetic from the station. The CDI centres when the OBS is set to the desired radial; the TO/FROM flag shows direction.

VOR line-of-sight range

Usable VOR range is about 1.23 × √(height in feet) NM. At 1,000 ft, expect roughly 39 NM line-of-sight reception.

ADF relative bearing

The ADF needle points to the station relative to the aircraft nose. Relative bearing plus heading gives the magnetic bearing to the station.

DME slant range

DME measures slant range, not ground distance. The error is negligible beyond about 3 NM from the station at typical altitudes.

ILS frequencies

The localiser transmits on 108.10–111.95 MHz (odd tenths); the glideslope transmits on 329.15–335.00 MHz. Fly to keep both indications centred.

RAIM satellite requirement

RAIM detects GNSS faults. Five satellites are needed for fault detection; six are needed for fault detection and exclusion.

GNSS altitude datum

GPS altitude is ellipsoidal (WGS-84), not pressure altitude. Do not use it for altimetry; use the aircraft altimeter set to the correct pressure setting.

Wind direction convention

Wind is named by the direction it comes from. A 270/20 wind comes from 270° at 20 kt, producing a headwind on a westerly track.

Wind component formulas

Headwind or tailwind = wind speed × cos(angle to track). Crosswind = wind speed × sin(angle to track).

Southern Hemisphere veer

In the Southern Hemisphere, wind veers (turns clockwise) with height and backs (turns anticlockwise) with descent. Surface friction reduces wind speed to about two-thirds of gradient wind.

Buys Ballot's law

In the Southern Hemisphere, stand with your back to the wind and low pressure lies on your right.

Föhn effect

Air descending the lee side of the Southern Alps warms and dries, producing strong, gusty northwesterlies in Canterbury and Otago.