Navigation Displays Flashcards
What is the purpose of the Head Up Display (HUD)?
The purpose of the HUD is to display essential flight information in line of sight ahead of the aircraft.
What does ‘field of view’ mean in the context of Head Up Displays (HUD)?
It indicates the angle, vertically as well as horizontally, subtended at the pilot’s eye, at which the combiner displays symbology in relation to the outside view.
What is the effect of using a HUD with a limited field of view?
Having a low field of view means the pilot will have a smaller cone angle at which he can see the information displayed on the HUD, leading to lesser performance due to poor ergonomics.
How does a CRT operate?
It creates electrons that are focused into a beam and are deflected in different directions to display information on the HUD.
What are the advantages of using ‘Diffractive optics’ on a HUD?
Improved FOV, requires less light to achieve equal or better brightness than refractive, low power CRT’s can be used, allows FLIR and Radar imagery to be displayed.
What is ‘cursive writing’ in the context of HUD?
The electron beam draws ‘line’ the same way as a pencil drawing on paper.
What is ‘raster scan’?
The ‘spot’ is moved over the whole area of the screen in a series of parallel horizontal lines, and an image is built up by varying the brightness of the spot during the scan.
Label the items from the diagram of HUD general mode symbols.
a) aircraft symbol, b) Horizon bars, c) Pitch bars, d) airspeed indication, e) height, f) angle of attack, g) vertical speed, h) heading.
What is one advantage of using an Electronic HSI (EHSI) over a conventional HSI?
The display is software driven; any changes can be done by software changes.
Label the items a to c from the diagram of an EHSI.
a) speed, b) Height, c) deviation bar.
What are 4 advantages of using flat panel displays over CRT displays?
- Smaller, lighter 2. Cheaper 3. More reliable 4. Less power.
What are 3 types of flat panel displays used in Avionic systems?
- Light Emitting Diode (LED). 2. Liquid Crystal Display (LCD). 3. Active Matrix LCD (AMLCD).
What is the purpose of ‘soft keys’ used on MFDs?
This allows each display to show any type of information. Soft keys can assume various functions depending on the mode of the display.
What is ‘Built In Test Equipment’ (BITE)?
Software used that is capable of detecting failures in a system. In modern aircraft, this facility is now the technician’s main aid to fault finding.
Describe the term ‘diffractive optics’ as used in a HUD.
Diffraction is the spreading or bending of waves as they pass round the edge of an obstacle or through an opening whose size is roughly the same as the wavelength of the waves.
