« Previous Next »

HUD Cathode Ray Tube

Technical Information

Catalogue No: C1685
Category: Head-Up Display [HUD]
Object Type: Module/Sub-Assembly/Component
Object Name: HUD Cathode Ray Tube
Part No: XAP0814S6-1
Serial No: None
Manufacturer: Brimar
Division: Unknown
Platform(s): Boeing 737
Year of Manufacture: 2003
Dimensions: Width (mm): 88
Height (mm): 77
Depth (mm): 190
Weight (g): 794
Location: Cupboard CA (CRTs) [Main Store]

Brimar Limited
Cathode Ray Tube
Made in England
CRT Type XAP0814S6-1
Part Number: AE012956
Serial No. -
Factory Ident No: 3M944000
Code Ident U3008
D. Code 0352M
Drive Cursive 31.3v
Focus Cursive 3460v
Cut Off 55.1v


This is an experimental monochrome precision face tube with electrostatic focus, magnetic deflection and used a P43 phosphor Tube but is very similar to the production unit fitted to the Civil HUD 2020 and 2022. The CRT narrow band P43 Phosphor operates with a Rugate notch Combiner Glass. .A Matching Card with deflection current feedback resistors would normally be fitted to the flat area. This CRT Assembly has 960mm cable (with connector) for its drive signals.
The reference document lists this as fitted to the ‘2022 HUD’ which was a variant of the HUD 2020™ fitted to the Boeing 737NG.
The 2020 system was designed from the outset to be expandable to show cursive, raster and cursive over raster displays such that sensors such as ALMW, FLIR or television systems can be considered. The HUD 2022 was aimed at producing a smaller derivative of the 2020 and work began in January 1997 with delivery of prototype hardware in 1998.
The date code is assumed to be yywwd (yy=year, ww=week number, d=?)

In a cockpit of a transport aircraft there are two general areas in which a projection unit can be installed: the glareshield or the overhead area. The overhead area is generally preferred (the C-17 was a notable exception) but installation is bounded by the structure and pilot’s head clearance. In general, the space available reduces sharply going outboard and increases going inboard. Overhead switch panels and eyebrow windows often reduce the space available. Overhead Projection Units were developed by the Company for civil and business aircraft systems in conjunction with Honeywell. The system was known as the 2020 because of the obvious connection with good vision. In 1996 the 2020 design was reduced in size and this new system was called the 2022 HUD.

In 1997 American Airlines solicited replies to a Request For Proposal for a HUD in its Boeing 737-800 and the Company won this major order for 75 displays valued at over £120m. This was a significant breakthrough into a major new business area with the initial order extending to up to 400 extra 737s on which American Airlines held purchase rights, plus possible fitment in other types in the airline's fleet, such as the MD-80 and 757-200.

The system comprises the Overhead Unit, the Combiner Assembly and Control Panel, a Mounting Tray and a Drive Unit. The Overhead Unit contains the Optical Relay assembly the CRT and the electronics with an integral HV Power Supply. The optical system gives a large eye motion box of 20 x 15 x 7.5cms.

The system operates in a cursive or cursive on raster mode to permit the use of sensor video and the TFoV is 30deg x 24deg. Cat 3 Certification was gained in a record two years under the leadership of Brian Harris who coordinated the liaison with the FAA.

American Airlines retrofitted the VGS into 22 Boeing 737-800’s which have been delivered, plus another eight due for delivery over the next four months. All retrofits were carried, out at the rate of one a week, by Marconi Flight Systems at Mojave, California, where the flight tests were carried out. The balance of the fleet was equipped by Boeing at Renton, Washington, around the first quarter of 2000.

The HUD gives guidance in Take Off and Go-Around the HUD providing positive guidance and 'v' speed bugs which enable take off in reduced runway visual range conditions (RVR) down to 90m (300ft)

In Approach the HUD provides guidance from localizer capture right down to touchdown, including all the necessary annunciations from "outer marker" to "idle". The symbology auto-declutters at Cat III decision height. In Landing from Cat III decision height, the HUD provides guidance down to touchdown including a flare cue and engine idle prompt, Positive centreline rollout guidance is also provided.

The more recent Cathode Ray Tube (CRT) for the Company Pilot’s Display Units are supplied as a CRT Assembly incorporating the CRT within its mu-metal housing. The CRT has a deflection coil within the casing which magnetically deflects the beam; focussing is electrostatic. The final anode operates at a high voltage of 18kV or more and the focus voltage is in the range 3-5kV.
A range of fine grain phosphors are used on the screen and the inside face, on which the phosphor is deposited, is accurately aligned to the mounting flange of the tube to ensure it coincides with the optical module's image plane.
When the CRT Assembly is fitted with its Matching Card it forms a Tube Unit Assembly (TUA).
The latest raster/cursive CRTs have a blank or silvered area usually at the bottom of the screen where the beam is deflected for a beam current calibration test. This is found on F-16 C/D (which introduced the idea), LANTIRN and Typhoon.

4500 Series GEC Ferranti HUD: This TUA operates in a raster or cursive mode and uses a P43 phosphor.
C-17 HUD: The circular faceplate of this CRT is blanked top and bottom to match the shallow prism optics in the relay. A P43 phosphor is used and the HUD was planned to have growth to a raster display but this was not installed. This part number in the reference database is wrongly attributed to EFA.
F-5 HUD: This is a conventional TUA and is cursive mode only with a P1 phosphor
F16A/B HUD: It was during this programme that the TUA became a subcontract item. The cursive only TUA uses a P1 phosphor
F-16C/D HUD: A large circular screen with a test area and using a P1 phosphor The TUA operates in raster/cursive and combined modes. 
Gulfstream HUD: A truncated CRT operating in cursive modes with a P43 phosphor
LANTIRN HUD: A truncated CRT operating in raster/cursive and combined modes with a P43 phosphor
Typhoon HUD: A truncated CRT operating in raster/cursive and combined modes with a high drive P53 phosphor

Click to enlarge Click to enlarge Click to enlarge
Related Items: