NZ CAA PPL Navigation cheat sheet

True airspeed (TAS) from calibrated airspeed: TAS ≈ CAS × (1 + 0.02 × altitude in thousands of feet); at 8,000 ft a 100 kt CAS gives about 116 kt TAS.

Density altitude rises about 120 ft per 1 °C above ISA temperature at a given pressure altitude; high density altitude increases TAS for a given IAS and lengthens takeoff and climb.

Fuel plan: trip fuel + contingency (typically 10% of trip or 5 min holding, per operator) + alternate fuel + final reserve (30 min for VFR in NZ) + taxi. Compare against usable fuel, not total capacity.

Wind triangle: heading = track ± wind correction angle (WCA), where sin(WCA) = (wind speed × sin(wind angle to track)) / TAS; use the maximum-drift method for quick estimates.

Ground speed from wind triangle: GS = TAS × cos(WCA) − wind speed × cos(wind angle to track); a direct headwind reduces GS by the full wind component.

1 in 60 rule: a 1° tracking error puts you 1 NM off track after 60 NM. Cross-track error = distance flown × track error / 60.

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

Weight and balance: compute CG from moments (weight × arm) and confirm it stays inside the forward and aft limits for takeoff, zero fuel, and landing configurations.

Pre-flight NOTAM and weather check: obtain TAF, GAF, METAR, SIGMET, and NOTAMs for departure, route, destination, and alternate; note any airspace restrictions or temporary hazards.

DR position = last known position + (heading × TAS × time) corrected for wind; update at least every 30 minutes or at each turning point.

Time en route = distance / ground speed. With 120 kt GS, 45 NM takes 22.5 min; convert minutes to decimal hours before multiplying.

Fuel used = fuel flow (L/h or gal/h) × time in hours; a 40 L/h flow over 1.5 h uses 60 L.

Mental DR: 1 NM per minute at 60 kt; 2 NM/min at 120 kt; 3 NM/min at 180 kt. Scale linearly for other speeds.

Wind correction angle sign: wind from the left requires a heading to the left of track (negative WCA); wind from the right requires a heading to the right.

Drift = difference between heading and actual track; if the planned WCA was correct, drift is zero.

Revised heading after a fix: new heading = old heading + (track error) + (closing angle to destination), each computed by the 1 in 60 rule.

Top of descent (approximate): 3 NM per 1,000 ft of altitude to lose at a 3° profile; at 6,000 ft, plan about 18 NM out.

NZ 1:250,000 topographical charts: 1 cm = 2.5 km; 1:500,000: 1 cm = 5 km. Use the scale bar for quick distance checks.

Grid references: eastings then northings ("along the corridor, up the stairs"); read to the nearest tenth of a grid square for precision.

Contour interval on NZ 1:50,000 charts is typically 20 m; closer contours mean steeper terrain and stronger mechanical turbulence.

Track crawling: pick two or three prominent features on or near track (lakes, road junctions, coastlines) and time the legs between them.

Map orientation in flight: hold the chart with north up; rotate the chart, not your head, to match the direction of travel.

Magnetic variation in NZ is about 20–25°E and changes slowly; apply variation to convert true to magnetic ("east is least" for magnetic heading).

Feature identification: use shape, size, colour, and surrounding context; a straight grey line may be a road, a power line, or a stopbank - confirm with two cues.

Position fix techniques: two-line fix (e.g., road and river), one-line plus distance, or a single prominent feature with a radial/DME from a navaid.

VOR: bearing is magnetic from the station; CDI centres when the OBS is set to the desired radial. TO/FROM flag indicates whether the selected course leads to or from the station.

VOR accuracy is about ±1–2°; usable line-of-sight range ≈ 1.23 × √(height in feet) NM (e.g., 1,000 ft gives about 39 NM).

NDB/ADF: the needle points to the station relative to the aircraft nose; relative bearing + heading = magnetic bearing to the station.

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

ILS: localiser provides lateral guidance (108.10–111.95 MHz, odd tenths); glideslope provides vertical guidance (329.15–335.00 MHz); fly to keep both centred.

GNSS: RAIM (receiver autonomous integrity monitoring) detects faults; a minimum of 5 satellites is needed for RAIM fault detection, 6 for exclusion.

GPS altitude is ellipsoidal (WGS-84), not pressure altitude; do not use it for altimetry.

Waypoint sequencing: use direct-to or flight-plan mode; monitor CDI scaling (typically ±1 NM en route, ±0.3 NM terminal) for sensitivity changes.

Wind is named by the direction it comes from; 270/20 means wind from 270° at 20 kt.

Wind components: headwind/tailwind = wind speed × cos(angle to track); crosswind = wind speed × sin(angle to track).

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 the gradient wind.

Buys Ballot's law (Southern Hemisphere): stand with your back to the wind, and low pressure is 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.

Sea breeze: develops during the day as land heats faster than sea; onshore wind strengthens in the afternoon and reverses at night.

Mountain wave and rotor turbulence: expect strong downdrafts and mechanical turbulence on the lee of ridges when wind speed at ridge height exceeds about 20 kt.

TAF validity is typically 24–30 hours; GAF (graphical area forecast) covers NZ and is issued several times daily. Check the issue time and validity period before use.

Icing risk: visible moisture plus temperatures between 0 °C and −20 °C; freezing rain is the most hazardous because it can exceed the aircraft's de-icing capability.