(HUD) Head Up Display System or (HGS) Head Up Guidance System as it is widely called is a system that is located in the windscreen of the cockpit to provide better visual cues to the Pilot, without looking below at his Primary Flight Displays located in the panel.
The benefit of using the system is that the Pilots are constantly looking outside the cockpit, at the Transparent flight displays located at the windscreen and monitoring their Approach on instruments at the same time, being backed by the visual cues to the outside ground reference.
This decreases the stress caused by constantly changing focus of eye by viewing inside the cockpit on instruments for a while or till DH or MDA and then trying to look for the visual cues outside the cockpit through windscreen.
Since the system utilizes the transparent foldable display located in front of the windscreen, it can be used to fly an approach without changing the focus of the eye from the early approach to the roll out point.
It uses clear combiners located between the Pilot’s eyes and the windscreen to display essential flight information within the Pilot’s field of view.
The displayed information is projected on a relay lens using a Monochromatic Holograph symbol, projected from a Cathode Ray Tube.
The display on the transparent screen includes all the information of an EFIS system, including Airspeed Indicator, Altimeter, Vertical Speed Indicator, Radio Altimeter indications, Approach guidance by the Auto pilot on the Flight Director Guidance bars as well as ILS indicator and RMI indications.
The newer advanced system also shows TCAS traffic indications as well as Wind shear Alert and Guidance and GPWS warning of the significant terrain in front of the A/c, which is displayed on the transparent foldable screen.
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ENHANCED HEAD UP DISPLAY SYSTEM
The EHUD is the same system as the HUD, except that in this an infra-red camera is located at the nose of the A/c to allow the Pilot to see the airport environment in poor weather.
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SYNTHETIC VISION SYSTEM
SVS is a system that displays terrain information, and airports structures utilizing the EGPWS information to calculate the A/c position as well as Terrain information on the flight route.
It draws a line of highway that is fixed on the display, denoting clear route and shows the A/c position with relation to the drawn highway line.
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ENHANCED SYNTHETIC VISION SYSTEM
ESVS is same as SVS system, except that it integrates sensor based Enhanced vision and utilizes Terrain data based Artificial Vision indications, to calculate A/c position, giving real life display of the outside world in the cockpit.