Flight planning terms

33 terms

ACO

Airspace control order. An order implementing the airspace control plan that provides the details of the approved requests for airspace coordinating measures. It is published either as part of the air tasking order or as a separate document.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [2] JP 3-30, p. GL-6

Center of gravity

CG. The point about which an aircraft would balance if it could be suspended there: the point at which its whole weight is assumed to be concentrated. It must lie within the limits the manufacturer sets.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 10-4

Compass heading

The reading on the compass that is followed to remain on the desired course, found by applying the compass deviation from the aircraft's deviation card to the magnetic heading.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 16-16

Datum

An imaginary vertical plane or line, set by the manufacturer, from which all arms are measured in weight and balance.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 10-5

DD Form 175

The DoD Military Flight Plan, equivalent to the FAA's domestic form 7233-1, with its elements in the same order. In US controlled airspace DoD aircraft may file it, but flights on it may not be eligible for RNAV departures and arrivals.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [4] Aeronautical Information Manual, p. 5-1-6; [4] Aeronautical Information Manual, p. 5-1-7

DD Form 175-1

The DoD Flight Weather Briefing form, the standard written weather brief. Weather units may use it or a locally derived alternative; a verbal or written brief should cover much of its content.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [5] AFH 11-203 Volume 2 / TC 3-04.14-2, p. 1.6.1.2

DD Form 1801

The DoD International Flight Plan, equivalent to the FAA's international form 7233-4. In US airspace it is recommended for military IFR flights and mandatory for any military flight leaving US controlled airspace or requesting performance-based navigation routing.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [4] Aeronautical Information Manual, p. 5-1-1; [4] Aeronautical Information Manual, p. 5-1-7

Dead reckoning

Navigation solely by means of computations based on time, airspeed, distance and direction.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 16-13

Density altitude

Pressure altitude corrected for nonstandard temperature: the altitude in the standard atmosphere with the same air density. The higher the density altitude, the poorer the aircraft's performance.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 11-3

Descent gradient

The altitude to lose divided by the distance to lose it in, in feet per nautical mile; 100 ft/NM is about 1° of pitch, so 300 ft/NM is about a 3° descent. Solved for distance, it gives where to start an en route descent.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [1] AFMAN 11-217 Volume 3, p. 3.7.1

Equal time point

ETP. The point along a leg between suitable airfields from which it takes the same time to return to the field behind as to continue to the field ahead. Because it depends on the ground speeds, it is not necessarily the midpoint. Computed as distance × GS returning ÷ (GS returning + GS continuing), measured from the field behind.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [1] AFMAN 11-217 Volume 3, p. 13.5.2

FDC NOTAM

Flight Data Center NOTAM. A NOTAM issued when it is necessary to disseminate regulatory information, such as amendments to instrument approach procedures and charts, and temporary flight restrictions.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [4] Aeronautical Information Manual, p. 5-1-3

FM

From. In a TAF, the start of a rapid and significant change, usually within an hour, after which the new conditions are forecast.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 13-9

Ground speed

GS. The actual speed of the aircraft over the ground: true airspeed adjusted for wind. It decreases with a headwind and increases with a tailwind.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 8-9

Magnetic heading

MH. The true heading with the magnetic variation applied: variation is added if west and subtracted if east.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 16-16

METAR

Aviation routine weather report. An observation of current surface weather reported in a standard international format, issued on a regular schedule. Each country may modify the code slightly.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 13-6

Military NOTAM

A NOTAM originated by the US Air Force, Army, Marine Corps or Navy about a military or joint-use navigational aid or airport in the National Airspace System, published in the international NOTAM format.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [4] Aeronautical Information Manual, p. 5-1-3

Moment

The weight of an item multiplied by its arm. The total moment divided by the total weight gives the aircraft's center of gravity.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 10-5

Moment arm

The horizontal distance from the datum to the center of gravity of an item: plus if aft of the datum, minus if forward of it.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 10-4

Nav log

The planning sheet and flight log for a route: for each leg, the course, wind correction, headings, distance, ground speed, time and fuel, worked out before flight and updated in flight.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 16-19

PIREP

Pilot weather report. A report from a pilot of the weather actually met in the air: cloud bases and tops, wind shear, turbulence and icing, which no other source can give.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 13-8

Pressure altitude

The height above the standard datum plane, the theoretical level where pressure is 29.92 inches of mercury: what the altimeter reads when set to 29.92. It is the basis for working out performance.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 11-3

PROB30

In a TAF, a 30 percent probability of thunderstorms and precipitation in the period given; it is not used in the first 6 hours of a 24-hour forecast.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 13-9

RVR

Runway visual range. The distance a pilot can see down the runway in a moving aircraft, reported in a METAR after the prevailing visibility as R, the runway, a slant and the range in feet.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 13-6

SPECI

A special METAR that can be issued at any time between routine reports, for rapidly changing weather, aircraft mishaps or other critical information.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 13-6

SPINS

Special instructions. Instructions published with the air tasking order that, with the airspace control order, give the airspace control and air defense directions every mission must follow: aircraft identification and engagement procedures, rules of engagement suited to the threat, and how tasks are assigned and reassigned. They are updated as often as required.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [2] JP 3-30, p. I-3; [2] JP 3-30, p. III-26

Standard briefing

The full preflight weather briefing, given in order: adverse conditions, VFR flight not recommended, synopsis, current conditions, en route and destination forecasts, winds and temperatures aloft, NOTAMs, ATC delays and other information.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 13-5

TAF

Terminal aerodrome forecast. A forecast for the five statute mile radius around an airport, valid for 24 or 30 hours and updated four times a day, using the same codes as the METAR.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 13-9

TEMPO

In a TAF, a temporary fluctuation in the weather expected to last less than an hour.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 13-9

True airspeed

TAS. Calibrated airspeed corrected for altitude and nonstandard temperature; for a given calibrated airspeed it increases with altitude. It is the speed used for flight planning and when filing a flight plan.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 8-9

True course

TC. The direction of the line connecting two desired points, drawn on the chart and measured clockwise in degrees from true north on the mid-meridian.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 16-16

True heading

TH. The direction, measured in degrees clockwise from true north, in which the nose of the aircraft should point to remain on the desired course.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 16-16

Wind correction angle

WCA. The angle between the course and the heading needed to hold it, found from the wind triangle. It is added to the true course if the wind is from the right and subtracted if it is from the left.

Pilots of every service planning a sortie: tasking, the route and nav log, fuel, flight plans, weather reports and aircraft performance

Source: [3] FAA-H-8083-25B, p. 16-16