aviation Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air craft such as hot air ...

, a flight director (FD) is a

flight instrument Flight instruments are the instruments in the cockpit of an aircraft that provide the pilot with data about the flight situation of that aircraft, such as altitude, airspeed, vertical speed, heading and much more other crucial information in fli ...

that is overlaid on the

attitude indicator The attitude indicator (AI), formerly known as the gyro horizon or artificial horizon, is a flight instrument that informs the pilot of the aircraft orientation relative to Earth's horizon, and gives an immediate indication of the smallest orie ...

that shows the

pilot An aircraft pilot or aviator is a person who controls the flight of an aircraft by operating its directional flight controls. Some other aircrew members, such as navigators or flight engineers, are also considered aviators, because they a ...

of an

aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...

the attitude required to execute the desired flight path. Flight directors are mostly commonly used during

approach Approach may refer to: Aviation *Visual approach *Instrument approach *Final approach Music * ''Approach'' (album), by Von Hertzen Brothers * ''The Approach'', an album by I:Scintilla Other uses *Approach Beach, a gazetted beach in Ting Kau, Ho ...

and landing. They can be used with or without

autopilot An autopilot is a system used to control the path of an aircraft, marine craft or spacecraft without requiring constant manual control by a human operator. Autopilots do not replace human operators. Instead, the autopilot assists the operator' ...

systems.

Description

Flight director (FD) modes integrated with autopilot systems perform calculations for more advanced automation, like "selected course (intercepting), changing altitudes, and tracking navigation sources with cross winds." FD computes and displays the proper pitch and bank angles required for the aircraft to follow a selected flight path. A simple example: The aircraft flies level on 045° heading at

flight level In aviation and aviation meteorology, a flight level (FL) is an aircraft's altitude at standard air pressure, expressed in hundreds of feet. The air pressure is computed assuming an International Standard Atmosphere pressure of 1013.25 hPa ...

FL150 at indicated airspeed, the FD bars are thus centered. Then the flight director is set to heading 090° and a new flight level FL200. The aircraft must thus turn to the right and climb. This is done by banking to the right while climbing. The roll bar will deflect to the right and the pitch bar will deflect upwards. The pilot will then pull back on the control column while banking to the right. Once the aircraft reaches the proper bank angle, the FD vertical bar will center and remain centered until it is time to roll back to wings level (when the heading approaches 090°). When the aircraft approaches FL200 the FD horizontal bar will deflect downwards thus commanding the pilot to lower the nose in order to level off at FL200. A flight director can be used with or without automation of the

flight control surfaces Aircraft flight control surfaces are aerodynamic devices allowing a pilot to adjust and control the aircraft's flight attitude. Development of an effective set of flight control surfaces was a critical advance in the development of aircraft. Ea ...

. The FD is commonly used in direct connection with the

Autopilot An autopilot is a system used to control the path of an aircraft, marine craft or spacecraft without requiring constant manual control by a human operator. Autopilots do not replace human operators. Instead, the autopilot assists the operator' ...

(AP), where the FD commands the AP to put the aircraft in the attitude necessary to follow a trajectory. The FD/AP combination is typically used in autopilot coupled low instrument approaches (below 200 feet

above ground level In aviation, atmospheric sciences and broadcasting, a height above ground level (AGL or HAGL) is a height measured with respect to the underlying ground surface. This is as opposed to height above mean sea level (AMSL or HAMSL), height above elli ...

GL, or CAT II and CAT III ILS

instrument approach In aviation, an instrument approach or instrument approach procedure (IAP) is a series of predetermined maneuvers for the orderly transfer of an aircraft operating under instrument flight rules from the beginning of the initial approach to a landi ...

es. The exact form of the flight director's display varies with the instrument type, either

crosshair A reticle, or reticule also known as a graticule, is a pattern of fine lines or markings built into the eyepiece of an optical device such as a telescopic sight, spotting scope, theodolite, optical microscope or the screen of an oscilloscope, ...

command bars Command may refer to: Computing * Command (computing), a statement in a computer language * COMMAND.COM, the default operating system shell and command-line interpreter for DOS * Command key, a modifier key on Apple Macintosh computer keyboards * ...

(so-called "cue").

References

Aircraft instruments Avionics {{aviation-stub

Description

See also

References