This is an “RSU,” a Runway Supervisory Unit:
They typically sit at the approach ends of runways at Air Force pilot training bases. During student training operations they are usually manned by a crew of 4: a Senior Controller, an Observer, Gear Spotter and Recorder. The Controller and Observer are IPs in the primary aircraft using the RSU’s runway. The Recorder and Gear Spotter are usually students.
The Controller’s job is as it implies. He/she is the individaul who controls the traffic and is usually a senior, experienced squadron IP. He is responsible for watching jets in the pattern primarily from the ‘perch’ through touchdown.
The Observer, another squadron IP, has the responsibility for the back half of the pattern, watching either the rollout portion of the runway, or clearing for the Closed Pattern – the part where the jet pulls up for another pattern.
The Gear Checker carries a pair of binoculars and is responsible for checking that 3 gear are ‘down and locked.’ More often than not, that the gear just look ‘normal.’
Then, the Recorder records all takeoffs and full-stop landings as well as any comments the Controller might have during the tour.
Usually a ‘tour’ lasts 4 hours or so, and a Controller might have 2-3 tours per week. Being an RSU Controller wasn’t anything I wanted to be, but I kinda got roped into it my last 6 months in the squadron – in 1977. And, I made the best of it, being recognized as Controller of the Quarter, 4th Quarter 1977… Go figure?