We discussed the required HUDs display data yesterday, but most exceed these minimum requirements. As the technology evolves more and more critical flight information can be displayed on the HUD. The flight path vector
data is useful for a pilot because it provides information about when the aircraft is losing energy, or during an instrument approach and landing by providing correct descent angle information along with the touchdown point on the runway. The navigation data and symbols
are used by the pilot where he fits the flight path vector
symbol inside a circle which allows the pilot to fly the correct flight path during an instrument approach and landing. Among the additional symbols currently available on some HUDs are:
boresight or waterline symbol which is fixed on the display and shows exactly where the nose of the aircraft is actually pointing;
flight path vector or velocity vector symbol which shows where the aircraft is actually going along with the sum of all forces acting on the aircraft;
acceleration indicator or energy cue which is normally to the left of the flight path vector symbol and which indicates whether the aircraft is accelerating or decelerating;
angle of attack indicator which shows the angle of the wing in relation to airflow;
navigation data which provides visual cues for approach, landing and instrument approaches.
The use of head-up displays allows commercial aircraft substantial flexibility in their operations. Systems have been approved which allow reduced-visibility takeoffs and landings, as well as full Category IIIc landings. Studies have shown that the use of a HUD during landings decreases the lateral deviation from centerline in all landing conditions, although the touchdown point along the centerline is not changed. Until next time keep your wings straight and level Hersch!
JetAviator7 The air is an extremely dangerous, jealous and exacting mistress. Once under the spell most lovers are faithful to the end, which is not always old age. Even those masters and princes of aerial fighting, the survivors of fifty mortal duels in the high air who have come scatheless through the War and all its perils, have returned again and again to their love and perished too often in some ordinary commonplace flight undertaken for pure amusement. — Sir Winston Churchill, Thoughts and Adventures, 1932.
ps: Don't forget to sign up for our newsletter "All Things Aviation" here!