A Cessna 182 was nearing the end of its landing roll on runway 22 at Dunkeswell aerodrome, Devon, UK, when a Boeing Stearman landed on top of it.

Remarkably, both pilots survived, but the Cessna pilot was badly wounded when propeller blades cut through the top of his cockpit.

The Air Accident Investigation Branch report describes what the Cessna pilot experienced: “With around 100 m to go to the [runway] intersection [where he intended to turn off to the right], the pilot reported that he heard and felt what seemed like an ‘explosion’ and then became aware of propeller blades rotating in front of his face. He recalled that the cockpit was filled with debris from the shattered windshield, shards of metal and splintered wood.”

It was a cloudy day but the visibility was pretty good below the cloud-base, which was 1,200ft above ground level, with a few patches at 600ft to 800ft. The AAIB says Dunkeswell witnesses described the weather as “workable”.

The pilots of both aircraft say they made calls on the Dunkeswell Radio frequency, but only the Cessna pilot received a reply.

Both pilots were alone in their aircraft, and both of them were experienced aviators.

Neither was aware of the other aircraft’s presence in or near the Dunkeswell circuit, and at the point of collision neither had seen the other.

If I were to stop the story here, even experienced general aviation pilots would wonder how this situation could possibly have developed. The answer, as usual, is that lots of factors combined; but even after reading the AAIB’s report, some questions remain unanswered.

The assembled contributory factors – in no particular order – are these: Dunkeswell Radio maintained an imperfect listening watch for its air-ground communication service (not ATC as such), the duty officer having multiple other duties while on watch; the Cessna pilot (G-OMAG) intercepted final approach from the “dead side” without clearing the non-standard arrival; the Stearman pilot (N68427), based at Dunkeswell, states he made several calls to Dunkeswell Radio when returning to the circuit, but received no response; neither pilot heard any calls from the other, both believing they were alone in the circuit; forward visibility from the Stearman’s cockpit is limited, especially directly ahead and below the nose. Finally, the AAIB found that the airport operator was not aware that the main AIP (aviation information publication) entry for Dunkeswell did not contain reference to the requirement for inbound traffic to join the circuit via either the downwind or base legs of the active runway. Accordingly, commercial AIP providers did not do so either.

The sequence on the day (20 August 2021) goes something like this: the Cessna, having obtained prior permission to arrive at Dunkeswell, took off from Bodmin – about half an hour to the west – at 13:00. The Stearman had taken off from Dunkeswell at 13:05 to carry out some flying in the local area to the north, and returned later intending a couple of circuits.

At 13:26 the Cessna passed Exeter to its north, and at the same time the Stearman joined Dunkswell’s left hand circuit for runway 22 from the east, and carried out a touch-and-go at 13:29. The Stearman pilot said he made a radio call indicating his intentions but could not recall getting an acknowledgement. Following his touch-and-go, N68427 flew a left hand circuit (see illustration below), intending to land from a curved base leg into a short final approach, because the wing-down attitude provides better sight of the runway for a Stearman pilot.

At about 13:27 the Cessna pilot called Exeter and said he was continuing with Dunkeswell Radio, then called the latter and was informed runway 22 was active with a QFE of 986hPa.

The AAIB report says that when the Stearman entered the 22 left hand circuit from the touch-and-go, the Cessna was about a mile to the west of the airfield, the dead-side of the circuit. The Cessna pilot decided to turn north (see illustration above), then carry out a right hand loop onto the base leg, continuing the turn onto final approach from the dead side. At that point, says the Cessna pilot, he called “Golf alpha golf final 22”. There was no acknowledgement, and the pilot told the AAIB he thought his aircraft was alone in the circuit.

CCTV images of the two aircraft show the two aircraft on final approach, the Stearman slightly higher, initially curving in from the left of the runway extended centreline, the Cessna on the centreline. As they converged, the Stearman remained higher than the Cessna and slightly ahead of it, the latter overhauling the biplane because of its faster approach airspeed. When the Cessna touched down just beyond the displaced runway threshold, the Stearman was above and close behind it, with the Cessna in the pilot’s blind spot below the biplane’s nose.

As the Cessna slowed toward its intended turn-off, the Stearman “touched down” on top of it. The AAIB report provides the Stearman pilot’s perception of what was happening: “The pilot reported that the landing ‘didn’t feel right’ and that the aircraft was not responding to control inputs. He applied power to correct what he felt was a drift to the left, then reduced power to idle. The aircraft continued to swing further to the left, off the runway and onto the grass.” (see headline picture).

The Cessna pilot could not open his cockpit door, but the Stearman pilot managed to do it and helped him out. The airport fire and rescue service attended rapidly and doused the Cessna with foam because fuel was leaking from the left wing tank.

Because the airfield only provided an air-ground communication service, not ATC as such, communications are not logged, but the pilots and some airport witnesses report calls being made in this case. The mystery is: why didn’t either pilot hear the other’s calls?

The UK Civil Aviation Authority’s Skyway Code provides plenty of apposite advice for this serious incident. One piece is this: “If you believe the circuit is clear but are not sure, there is no harm in asking over the radio whether there is any other traffic – it is not unknown for pilots to stop making position calls if they believe they are alone in the circuit.” Another is to stick rigidly to circuit procedure, which would include not joining from the dead side.