Aeronautical Terms beginning with H
HAA
Height Above Airport.
HAL
Height Above Landing.
HAT
Height Above Touchdown Elevation.
Hazardous attitudes
Five aeronautical decision-making attitudes that may contribute to poor pilot judgment: antiauthority, impulsivity, invulnerability, machismo, and resignation.
Hazardous Inflight Weather Advisory Service (HIWAS).
Service providing recorded weather forecasts broadcast to airborne pilots over selected VORs. Discontinued on January 8, 2020.
Head-Up Display (HUD)
See Head-Up Guidance System (HGS)
Head-Up Guidance System (HGS)
A system which projects critical flight data on a display positioned between the pilot and the windscreen. In addition to showing primary flight information, the HUD computes an extremely accurate instrument approach and landing guidance solution, and displays the result as a guidance cue for head-up viewing by the pilot.
Heading
The direction in which the nose of the aircraft is pointing during flight.
Heading indicator
An instrument which senses airplane movement and displays heading based on a 360° azimuth, with the final zero omitted. The heading indicator, also called a directional gyro (DG), is fundamentally a mechanical instrument designed to facilitate the use of the magnetic compass. The heading indicator is not affected by the forces that make the magnetic compass difficult to interpret.
Height Above Airport
The height of the Minimum Descent Altitude above the published airport elevation. This is published in conjunction with circling minimums.
Height Above Touchdown
The height of the Decision Height or Minimum Descent Altitude above the highest runway elevation in the touchdown zone (first 3,000 feet of the runway). HAT is published on instrument approach charts in conjunction with all straight-in minimums.
Height above touchdown elevation (HAT)
The DA/DH or MDA above the highest runway elevation in the touchdown zone (first 3,000 feet of the runway).
HEMS
Helicopter Emergency Medical Service
HF
High Frequency.
HFDL
High Frequency Data Link
Hg
Abbreviation for mercury, from the Latin hydrargyrum.
HIRL
High Intensity Runway Lights
HITS
Highway In The Sky
HIWAS
Hazardous Inflight Weather Advisory Service. Discontinued on January 8, 2020.
Hold For Release
Used by ATC to delay an aircraft for traffic management reasons; i.e., weather, traffic volume, etc. Hold for release instructions (including departure delay information) are used to inform a pilot or a controller (either directly or through an authorized relay) that an IFR departure clearance is not valid until a release time or additional instructions have been received.
Hold In Lieu Of Procedure Turn
A hold in lieu of procedure turn shall be established over a final or intermediate fix when an approach can be made from a properly aligned holding pattern. The hold in lieu of procedure turn permits the pilot to align with the final or intermediate segment of the approach and/or descend in the holding pattern to an altitude that will permit a normal descent to the final approach fix altitude. The hold in lieu of procedure turn is a required maneuver (the same as a procedure turn) unless the aircraft is being radar vectored to the final approach course, when “NoPT” is shown on the approach chart, or when the pilot requests or the controller advises the pilot to make a “straight-in” approach.
Hold Procedure
A predetermined maneuver which keeps aircraft within a specified airspace while awaiting further clearance from air traffic control. Also used during ground operations to keep aircraft within a specified area or at a specified point while awaiting further clearance from air traffic control.
Holding
A predetermined maneuver that keeps aircraft within a specified airspace while awaiting further clearance from ATC.
Holding Fix
A specified fix identifiable to a pilot by NAVAIDs or visual reference to the ground used as a reference point in establishing and maintaining the position of an aircraft while holding.
Holding pattern
A racetrack pattern, involving two turns and two legs, used to keep an aircraft within a prescribed airspace with respect to a geographic fix. A standard pattern uses right turns; nonstandard patterns use left turns.
Homing
Flying the aircraft on any heading required to keep the needle pointing to the 0 relative bearing position.
Horizontal situation indicator (HSI)
A flight navigation instrument that combines the heading indicator with a CDI, in order to provide the pilot with better situational awareness of location with respect to the courseline.
HSI
Horizontal Situation Indicator.
HUD
Head-Up Display.
Human factors
A multidisciplinary field encompassing the behavioral and social sciences, engineering, and physiology, to consider the variables that influence individual and crew performance for the purpose of optimizing human performance and reducing errors.
Hypoxia
A state of oxygen deficiency in the body sufficient to impair functions of the brain and other organs.
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