CAA NZ IR Instruments and Navaids cheat sheet

Pitot-static: ASI uses total pressure from pitot and static pressure from static port. Blocked pitot with drain open causes ASI to read zero; blocked pitot with drain blocked causes ASI to act like an altimeter (climb shows increasing IAS).

Blocked static port: ASI over-reads in climb and under-reads in descent; altimeter freezes at blockage altitude; VSI shows zero after transient.

Altimeter setting: QNH set on subscale gives altitude above mean sea level; QFE gives height above aerodrome reference point; QNE (1013.25 hPa) used above transition level for flight levels.

Altimeter error: 1 hPa pressure error ≈ 30 ft altitude error near sea level. Temperature error: high temperature causes altimeter to under-read (aircraft higher than indicated).

VSI lag: typically 6–9 seconds to settle; instantaneous VSI indicates trend. In a steady climb or descent, VSI shows rate after lag.

Turn coordinator vs turn-and-slip: turn coordinator shows rate of turn and roll (ball in slip/skid); turn-and-slip shows yaw rate and bank. Both use gyroscope precession.

Attitude indicator: gyroscope with two degrees of freedom (vertical spin axis); erect and caged for fast erection. Precession causes errors during prolonged turns; erect after 5–10 minutes straight flight.

Heading indicator: gyroscope with horizontal spin axis; must be set to magnetic compass periodically due to precession. Magnetic compass errors: variation, deviation, dip, turning and acceleration errors.

Instrument system checks: pitot heat, static drains, alternate static source, gyro suction/vacuum (if applicable), and electrical load. For IFR, verify pitot heat and anti-ice before flight into icing conditions.

VOR: line-of-sight, frequency 108.0–117.95 MHz. CDI indicates course deviation; TO/FROM flag indicates direction to/from station. Accuracy ±1° (plus installation error).

VOR radial vs bearing: the radial is the magnetic course FROM the station. To fly TO the station on a given radial, set the OBS to the reciprocal of the radial.

VOR checks: airborne check within 25 NM of a VOR checkpoint, tolerance ±6°; ground check at designated point ±4°; dual VOR check ±4° between two VORs.

NDB/ADF: frequency 190–1750 kHz (MF). ADF points to the station relative to aircraft heading; relative bearing + magnetic heading = magnetic bearing to station.

DME: frequency paired with VOR or ILS (UHF 962–1213 MHz). Indicates slant range distance in nautical miles; accuracy ±0.5 NM or 3% of distance, whichever is greater. Ground speed and time-to-station derived from DME.

ILS: localizer (108.10–111.95 MHz) gives lateral guidance; glideslope (329.15–335.0 MHz) gives vertical guidance. Localizer course width 3°–6°; glideslope angle typically 3° (2.5°–3.5°).

ILS categories: CAT I decision height 200 ft, RVR 550 m; CAT II DH 100 ft, RVR 300 m; CAT IIIa DH 50 ft, RVR 200 m; CAT IIIb DH <50 ft, RVR 75 m; CAT IIIc no DH/RVR.

Marker beacons: 75 MHz. Outer marker (blue, 400 Hz, dashes) at glideslope intercept; middle marker (amber, 1300 Hz, alternating dots/dashes) near DH; inner marker (white, 3000 Hz, dots) at threshold for CAT II/III.

NDB errors: night effect (skywave interference), coastal refraction, mountain effect, electrical interference. VOR errors: terrain/line-of-sight, multipath, scalloping.

RNAV: navigation that permits operation on any desired flight path within coverage of navigation aids or within limits of self-contained aids, or a combination.

RNP: RNAV with on-board performance monitoring and alerting (OPMA). RNP AR requires special aircraft qualification and crew training.

Waypoint types: fly-by (turn anticipation) and fly-over (no anticipation). Fly-by is default; fly-over used for specific procedures (e.g., holding, approach).

Path terminators: IF (initial fix), TF (track to fix), DF (direct to fix), CF (course to fix), FA (fix to altitude), CA (course to altitude), VA (heading to altitude), VM (heading to manual termination), FM, HM (holding), RF (radius to fix).

RNAV equipment: GNSS, DME/DME, VOR/DME, INS/IRS. Each has accuracy and coverage limitations; DME/DME requires line-of-sight and specific geometry.

Contingency procedures: if RNAV equipment fails, revert to conventional navigation or advise ATC. For RNP AR, execute missed approach if alert limits exceeded.

Turn anticipation: for fly-by waypoints, the aircraft begins turn before the waypoint to roll out on next segment. Distance depends on speed, bank angle, and course change.

Parallel offset: RNAV systems allow offset tracks (e.g., 5 NM) for strategic lateral offsets; ATC must be advised. Offset is not permitted on RNP AR approaches.

GNSS: GPS (USA), GLONASS (Russia), Galileo (EU), BeiDou (China). Augmentation: ABAS (aircraft-based), SBAS (satellite-based, e.g., WAAS, EGNOS), GBAS (ground-based).

GPS accuracy: standard positioning service ~15 m horizontal, 95%. With SBAS, accuracy improves to ~1–2 m. RAIM (receiver autonomous integrity monitoring) detects anomalies.

RNP values: RNP 1 (1 NM), RNP 0.3 (0.3 NM), RNP 0.1 (0.1 NM). RNP AR APCH typically RNP 0.3 to 0.1. PBN (performance-based navigation) includes RNAV and RNP.

Alert limits: RNP 1 alert limit 2 NM; RNP 0.3 alert limit 0.6 NM; RNP 0.1 alert limit 0.2 NM (2× accuracy). Exceeding alert limit requires immediate action (e.g., missed approach).

RAIM prediction: required for GPS approaches if not SBAS. RAIM availability depends on satellite geometry and number of satellites; check NOTAMs or prediction tools.

FDE (fault detection and exclusion): required for RNP AR; can exclude faulty satellite. RAIM only detects; FDE detects and excludes.

SBAS: provides vertical guidance (LPV) and improves integrity. WAAS covers North America; EGNOS Europe; MSAS Japan; GAGAN India. Not all SBAS certified for all phases.

GNSS errors: ionospheric delay, tropospheric delay, multipath, satellite clock/ephemeris errors. Ionospheric errors largest near equator and during solar activity.

AIP New Zealand: contains GEN (general), ENR (en-route), AD (aerodromes) sections. Charts: ENR route charts, AD aerodrome charts, instrument approach charts (IAC), departure (SID), arrival (STAR).

SID/STAR: SID provides obstacle clearance from runway to en-route; STAR provides transition from en-route to approach. Charts include routing, altitudes, speed restrictions, and gradients.

Instrument approach: precision (ILS, GLS), APV (LPV, LNAV/VNAV), non-precision (VOR, NDB, LNAV, LOC). Each has minima: DA/DH or MDA, visibility/RVR, and missed approach procedure.

MDA vs DA: MDA is minimum descent altitude for non-precision; DA is decision altitude for precision/APV. DA includes height loss during missed approach; MDA requires level flight until missed approach point.

Missed approach: climb to specified altitude, follow routing, and hold or proceed as instructed. Missed approach point (MAPt) for precision is DA; for non-precision, at MDA or at a fix.

Take-off minima: specified in AIP or charts; may include RVR/visibility, ceiling, and alternate requirements. Low-visibility take-off (LVTO) requires specific approval and RVR.

Alternate requirements: for IFR, destination alternate required unless certain conditions met (e.g., two approaches with separate runways, weather margins). AIP NZ specifies alternate minima.

AIP supplements and NOTAMs: check for temporary changes (e.g., runway closures, navaid outages, procedure amendments). NOTAMs take precedence over published charts.

Chart symbology: MSA (minimum sector altitude) 25 NM circle; MORA (minimum off-route altitude) grid; transition level/altitude; speed restrictions; mandatory reporting points.