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F-5 Pilot's Display Unit

Technical Information

Catalogue No: C0022
Category: Head-Up Display [HUD]
Object Type: Display Unit
Object Name: F-5 Pilot's Display Unit
Part No: 79-090-03
Serial No: None
Manufacturer: GEC Avionics
Division: Airborne Display [ADD]
Platform(s): F-5
Year of Manufacture: circa 1988
Dimensions: Width (mm): 140
Height (mm): 295
Depth (mm): 680
Weight (g): 8,600
Location: Rack RAA14 (HUD DUs) [Mezzanine Store]

Pilot's Display Unit
Contract F09603-84-G-1438
Dsgn Act K0656
PN 79-090-03
Mfr K0656
Ser. No.
[optics underside]
Part No. 2501-00049.
Serial No. f5E 0007
Mfr Code K6111
Mfr Part No. 039909
Cont No. F09603-84-G-1438/SA15
[optics handwriten]
B:-A -.44mR, E -1.39mR
M:-M 0.999, E1.002


In 1988 the Royal Thai Air Force ran the First Capability Upgrade on their F-5 aircraft. The DoD had placed the Contract in 1984 and the update was to provide a ‘lead-in’ fighter for the F-16. The programme included a new HUD/WAC (Head-Up Display/Weapon Aiming Computer) from GEC Marconi, decoy system AN/ALE-40 and warning detection system AN/ALR-46 RWR (Radar Warning Receiver). During early 1986 through to mid 1987 GAv developed a simple cursive only PDU with a keypad Up Front Control Panel aft of a Video Camera. The basic design was subsequently used in a variant for a different aircraft. GAv Atlanta managed the programme and they also developed the HUD Electronics Unit which was based on the F-16 design with a 1553 bus. This PDU was used as a space model for the Indonesian F-5 and was a test fit in the aircraft. The space behind the blank panel on the aft end was for a Video Camera. (Possibly Part No. 79-093-01) This HUD needs some assembly of the various parts.

The handwritten inscription that can be seen on the aft face of the optical module housing refer to B[oresight] & M[agnification] corrections required for A[zimuth] & E[levation] axes.

The F-5 was sold to many countries and provided a simple but effective fighter aircraft with potential for avionic upgrade. The Company worked on various upgrade programmes and in each case a replacement for the existing  Lead Computing Optical Sight (LCOS) was offered.

The earliest such replacement is seen in Catalogue No. C0022. The HUDWAC consists of three line replaceable units; the Pilot’s Display Unit (PDU), an Electronics Unit (EU) and a Weapon Data Input Panel (WDIP).

The physical configuration of the HUDWAC was designed to be drop-in compatible with all known versions of the F-5E/F. Other than removal of the Lead Computing Optical Sight (LCOS) no rearrangement of existing systems nor structural modification was necessary; the new PDU mounts onto the same LCOS tray. The HUDWAC was made to be interchangeable between F-5E’s fitted with the APQ-153 radar and AHRS and those fitted with an APQ-159 radar and an INS without any modifications. The HUDWAC monitors the armament panel switch settings and the in-built software determines the required operating mode which overall makes the system easier to use than the original LCOS.

The PDU gives a field of view nearly twice that of the ASG-29 Lead Computing Optical Sight it replaces. The unit hosts a control panel with switches and a keypad through which mission data such as target elevation and barometric pressure can be loaded. A 16mm film camera or a colour video camera can be attached to the aft end of the PDU. In this aircraft the PDU is hard mounted to a pre-aligned mounting frame, rather than an adjustable Mounting Tray i.e. it is already boresighted to the airframe. The drawback to the installation is that the PDU has to be long and narrow which is reflected in the design of the circuit boards within the unit. The High Voltage Power Supply locates on the underside of the PDU and there would be a Gun Camera and an Up-Front Control Panel fitted to customer requirements.


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