CAA NZ IR Instruments and Navaids key terms

The network of pitot tube, static ports and associated plumbing that supplies total and static pressure to the airspeed indicator, altimeter and vertical speed indicator. Blockages or leaks cause specific, recognisable instrument errors.

The pressure value dialled into the altimeter's Kollsman window so the instrument displays height above a chosen reference. QNH gives altitude above mean sea level, QFE gives height above a aerodrome reference point, and standard pressure 1013.2 hPa gives flight levels.

The altitude, published in the AIP for each aerodrome or area, at or below which aircraft fly on QNH and above which they set standard pressure and fly flight levels. It is not a fixed height nationwide in New Zealand.

A surface of constant pressure shown on the altimeter when the subscale is set to 1013.2 hPa, expressed in hundreds of feet, for example FL150. It provides a common reference for traffic separation above the transition altitude.

Markings on the dial showing flap operating range (white), normal operating range (green), caution range (yellow) and never-exceed speed (red line). They are type-specific and must be known from the aircraft flight manual.

The maximum speed at which full deflection of a single flight control may be applied without exceeding the design load factor, marked as VA. It decreases with weight, so the flight manual value applies only at maximum weight.

A gyroscopic instrument showing pitch and roll relative to the horizon. Its gyro relies on rigidity in space, so it is subject to apparent drift and must be caged or erected after prolonged manoeuvring or acceleration errors.

The gradual precession of a directional gyro away from true heading caused by the Earth's rotation and internal friction. It must be realigned periodically with the magnetic compass during flight, particularly after turns or long legs.

An instrument showing rate of turn and, indirectly, slip or skid through a ball in a curved tube. It supports standard-rate turns and coordinated flight, and its gyro is electrically driven in most light aircraft.

A turn of three degrees per second, completing 360 degrees in two minutes. The required bank angle increases with true airspeed, and the turn coordinator or turn needle is used to hold the rate.

The angular difference between true north and magnetic north at a given location, shown on charts as east or west. It is applied when converting between true and magnetic directions; New Zealand values differ between the North and South Islands.

The error in a magnetic compass reading caused by the aircraft's own magnetic fields and electrical equipment. It is recorded on a compass swing card and applied separately from variation.

A magnetic bearing from a VOR station, expressed in degrees, along which the aircraft's position lies. Tracking a radial inbound or outbound requires understanding the course deviation indicator's sensing, which reverses after station passage.

The maximum needle displacement on a course deviation indicator, corresponding to a defined angular or lateral offset from the selected course. Knowing this value lets a pilot convert needle deflection into distance from track.

A combined display integrating a heading reference with a course deviation indicator and glideslope pointer. It reduces head-down workload during instrument approaches because the aircraft's heading is shown relative to the selected course.

The vertical guidance component of a precision approach, typically transmitted on a UHF frequency paired with the localiser. The pointer shows deviation above or below the nominal descent path, and fly-up or fly-down sensing must be confirmed.

The lateral guidance component of an instrument landing system, transmitting on a VHF frequency in the 108 to 112 MHz band. It provides runway-aligned course guidance with a narrower beam than a VOR.

A precision approach aid combining localiser, glideslope and marker or distance information. Categories differ in decision height and required runway visual range, and low-visibility operations depend on aircraft and crew certification.

A non-directional beacon transmits an LF or MF signal, and the automatic direction finder in the aircraft displays the relative bearing to it. Tracking requires applying heading and relative bearing to derive magnetic bearing.

The angle measured clockwise from the aircraft's nose to the bearing of a station. Adding it to the aircraft heading gives the magnetic bearing to the station, which is the basis of ADF tracking.

Slant range in nautical miles from the aircraft to a distance measuring equipment transponder, not ground distance. Error grows with altitude, so DME readings overfly the station rather than reaching zero.

Navigation along any desired flight path using equipment that computes position independently of overflying ground aids. It permits route structures and approaches not tied to the location of VOR or NDB stations.

A defined geographical position identified by name or coordinates, used to build an area navigation route or procedure. Waypoints may be fly-by, where the aircraft turns early, or fly-over, where it must cross the point before turning.

A waypoint at which the aircraft begins its turn before reaching the point, so the curved path remains inside protected airspace. The turn anticipation depends on speed and the programmed bank angle.

A waypoint the aircraft must cross before starting any turn, used where early turning would leave protected airspace, for example at a holding fix or procedure turn. It is depicted with a four-pointed star on charts.

A gap in the programmed route that stops automatic navigation guidance until the crew inserts the next leg. It is a deliberate safeguard against the aircraft navigating an unintended path after a procedure or route change.

A navigation specification stating the lateral accuracy, in nautical miles, that an aircraft must achieve for at least 95 percent of flight time in a given airspace. It also implies onboard performance monitoring and alerting.

Global navigation satellite systems, including GPS and its augmentations, providing position, velocity and time. Aviation use depends on receiver approval, satellite geometry, and integrity monitoring such as RAIM or SBAS.

Receiver autonomous integrity monitoring, a function that checks whether the available satellites give a consistent position and warns when the geometry cannot support the required integrity. It is central to non-precision GPS approach planning.

An extension of integrity monitoring that identifies and removes a faulty satellite from the position solution rather than simply warning. It requires more satellites in view than basic detection alone.

An instrument approach procedure based on satellite navigation with a specified navigation accuracy, often using vertical guidance such as barometric vertical navigation. Minima and required equipment are published on the procedure chart.

Vertical navigation computed from barometric altitude rather than satellite geometry, used for approach vertical guidance. It depends on accurate altimeter setting and is subject to temperature limits published on the chart.

The altitude at which a missed approach must be initiated if the required visual reference has not been established. It is referenced to the altimeter and differs from decision height, which is measured above touchdown.

The lowest altitude permitted on a non-precision approach before the required visual reference is established. Descent below it is not allowed unless the runway environment is in sight.

A published procedure diagram showing track, distances, altitudes, frequencies, minima and missed approach instructions. In New Zealand these follow AIP New Zealand volume 4 format and must be read as a complete unit.

The lowest altitude providing a stated obstacle clearance, usually 1000 feet, within a sector around a navigation aid or aerodrome, typically within 25 nautical miles. It is a planning aid, not an approach altitude.

The minimum climb gradient required to maintain obstacle clearance on a departure or missed approach, often expressed as a percentage or feet per nautical mile. It may exceed the standard gradient and then demands specific aircraft performance.

The point on a non-precision approach at which the missed approach must begin if visual reference is not established, defined by distance, time or a navigation fix. It is distinct from the decision altitude used on precision approaches.

The official publication containing aeronautical information, including aerodrome data, routes, instrument procedures and charts. It is issued in volumes and supported by NOTAM and supplements, and is the authoritative source for procedure detail.

A notice distributed by the aeronautical information service giving time-critical information about hazards, changes or restrictions. Pilots must check NOTAMs relevant to the route and aerodrome before flight.