CAA NZ CPL Flight Navigation General key terms

A navigation method that calculates present position from a known starting point using heading, true airspeed, elapsed time and forecast wind, without reference to external position fixes. It is the fallback basis for every flight and must be cross-checked against fixes.

The vector construction combining true airspeed and heading with the wind velocity to give groundspeed and drift, and hence the track and heading actually required. Solving it produces heading, groundspeed, and estimated time enroute for the flight plan.

The angular difference between the aircraft's heading and the track actually made good over the ground, caused by wind. It is applied left or right of track to convert a required track into a heading.

The direction the aircraft nose points, measured from true north (true heading) or from magnetic north (magnetic heading). Magnetic heading equals true heading plus or minus magnetic variation, then adjusted for deviation.

The actual path over the ground from the last known position to the present position, expressed as a direction. Comparing it with the planned track reveals drift and any tracking error requiring correction.

The angular difference between true north and magnetic north at a given place, caused by the Earth's magnetic field. It is shown on aeronautical charts as east or west and must be applied when converting between true and magnetic directions.

The error of a magnetic compass caused by magnetic fields within the aircraft itself, such as electrical circuits and structure. It varies with heading and is recorded on a compass deviation card used to convert magnetic heading to compass heading.

A confirmed aircraft position obtained from an external source such as GNSS, VOR/DME, NDB bearings, visual ground features, or radar. Regular fixes update the DR plot and confirm or correct the wind and groundspeed assumptions.

A rule of thumb stating that a track error of one nautical mile over 60 nautical miles flown equals one degree, and that one degree of drift equals one nautical mile per 60 flown. It allows quick mental correction of heading and tracking.

The breakdown of required fuel into taxi, trip, contingency, alternate and final reserve components, plus any extra fuel. Each component has defined rules, and the plan must be revised in flight as actual consumption and winds differ.

The minimum fuel that must remain on landing, expressed as time at holding or cruise consumption, intended to cover an unforeseen delay or diversion. It is a protected quantity and declaring minimum fuel or Mayday fuel follows from it being at risk.

Fuel carried in addition to trip fuel to cover unforeseen factors such as wind, routing or consumption differing from plan. It is typically a percentage of trip fuel or a fixed time, depending on the operator's approved fuel policy.

The distance an aircraft can fly per unit of fuel, usually nautical air miles per kilogram or pound. It varies with altitude, mass and speed, and is used to select the most economical cruise level and power setting.

The speed of the aircraft through the air mass, corrected for altitude and temperature from indicated or calibrated airspeed. TAS is the input to the wind triangle and to fuel and time calculations.

The speed of the aircraft over the ground, being true airspeed combined with the wind component along track. It determines time enroute and fuel burned between waypoints.

The ratio of true airspeed to the local speed of sound, which depends on temperature. High-altitude jet operations use Mach for cruise and speed scheduling, and a Mach limit may apply to the aircraft structure.

A operator-set number balancing fuel cost against time-related cost to select cruise speed and climb/descent schedules in flight management computers. A low cost index favours fuel economy, a high one favours speed.

A ground beacon transmitting radial information so an aircraft receiver can determine its bearing from the station. Tracking a selected radial, or using two radials to fix position, provides a line of position for navigation.

A magnetic bearing from a VOR station, identified by the number shown on the course deviation indicator when the aircraft is on that bearing. Radials are magnetic and are used to define airways and positions.

A paired VOR and distance measuring equipment facility that gives both bearing and slant range from the station. The combination allows a single-station fix and is the basis of many airway and RNAV definitions.

A non-directional beacon transmits a signal that an automatic direction finder in the aircraft uses to display a relative bearing to the station. Applying heading gives a magnetic bearing, which is affected by coastal refraction and night effect.

The angle between the aircraft's nose (heading) and the direction to a radio station, measured clockwise. Adding relative bearing to heading gives the magnetic bearing to the station, used to plot an NDB line of position.

A locus of points along which the aircraft must lie, derived from a single navigation measurement such as a VOR radial, DME range, NDB bearing or GNSS range. Two or more intersecting lines give a fix.

A precision approach aid providing lateral guidance from a localiser and vertical guidance from a glide path, with marker beacons or DME for range. It supports approach navigation to defined decision heights.

A satellite-based positioning system, such as GPS or Galileo, that provides position, velocity and time to a receiver. Aviation use requires approved receivers, integrity monitoring and awareness of RAIM availability and signal degradation.

Receiver autonomous integrity monitoring, a function that checks whether enough satellites with consistent signals are available to trust the GNSS position. Loss of RAIM may make a GNSS-based approach unavailable and requires a prediction before flight.

A satellite-based augmentation system that broadcasts corrections and integrity information to GNSS receivers, improving accuracy and allowing lower approach minima. Coverage and approval depend on the region and the installed avionics.

Area navigation that allows an aircraft to fly a desired path between defined waypoints rather than directly to or from ground beacons. It relies on onboard computing and a suitable navigation source such as VOR/DME, DME/DME or GNSS.

A navigation specification that states the on-board performance monitoring and alerting required, expressed as a lateral accuracy value in nautical miles. RNP AR additionally permits radius-to-fix legs and reduced obstacle clearance.

A defined geographical point, identified by name or coordinates, used to build a route in an RNAV or flight management system. Waypoints may be fly-by or fly-over and may be linked by fixed-radius or track-to-fix legs.

An on-board computer that stores the route, performance data and navigation sensors, then computes guidance, fuel predictions and time estimates. Correct entry of route, winds and performance data is essential to its outputs.

A change in wind speed or direction over a short distance, horizontally or vertically, which can cause sudden airspeed and track changes. It is significant for takeoff, approach and flight planning near fronts and convective activity.

A narrow band of strong, often high-altitude westerly wind associated with large temperature gradients. Its position and strength strongly affect groundspeed, fuel burn and the choice of cruise level on long routes.

An oscillating airflow downwind of a mountain barrier, often marked by lenticular cloud and severe turbulence. It can produce strong downdrafts and altitude errors, affecting terrain clearance and route planning.

The vertical margin between the aircraft's path and the highest terrain or obstacle along the route. It is assured by minimum safe altitudes, sector safe altitudes and published procedure design gradients.

The lowest altitude providing a defined obstacle clearance within a specified area, such as a grid or route sector. It is published on charts and used to set a safe altitude before descent or in an emergency.

A chart showing airways, radio navigation aids, reporting points, minimum altitudes and airspace along a route. It is used to plan and monitor the navigation leg between departure and destination.

A defined corridor of airspace, usually based on radio navigation aids, within which aircraft are separated and cleared. Airways have designators, widths and minimum altitudes, and joining or crossing one requires a clearance.

The calculation confirming that the aircraft's mass and centre of gravity lie within approved limits for the planned loading. It uses basic empty mass, crew, fuel, payload and moment arms to produce the takeoff and landing figures.

The point through which the aircraft's total weight acts, expressed as a position along the fuselage. It must stay within a forward and aft limit for controllability, performance and structural safety throughout the flight.

The mass of the aircraft with all equipment, unusable fuel and operating fluids but without crew, passengers, payload or usable fuel. It is the starting figure in every mass and balance calculation.