Telescopic Sighting System

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The Telescopic Sighting System (TESS) was a sight used on the FV4201 Chieftain^[1] and RAF F-4 Phantom aircraft.^[2]

The TESS was trialed and introduced in the early 1980s originally as a tank sight for the FV4201 Chieftain. Surplus stocks were used on F-4 Phantom aircraft as a cost-saving measure for a long range daytime target identification device, whereas the USAF used the TISEO. The TESS was installed in the rear cockpit in the centre window section for the Radar Intercept Officer to use.^[3] It was boresighted to the aircraft weapons system and when locked on target, the target was magnified six times.^[4]

• Aircraft periscope