Background
Bagby Airfield is an unlicensed airfield with a grass runway oriented 06/24, measuring 710 m in length. Runway 06 has an upslope of 2.6%. The airfield has an air-to-ground (A/G) radio that is not always manned. Its website cautions that in light and no wind conditions, local pilots almost invariably land uphill and take off downhill, advising awareness of mixed direction traffic. On the day of the incident, the surface wind was estimated from 300° to 330° at 8 kt, with CAVOK conditions.
Aircraft and Pilots
Two aircraft were involved: a Cessna 172M Skyhawk, registration G-BTMR, built in 1975, powered by one Lycoming O-320-E2D engine; and a Diamond DA 42 Twin Star, registration G-PETS, built in 2006, powered by two Thielert TAE 125-01 engines.
G-BTMR was being operated as a private flight with two pilots on board. The commander held a Private Pilot's Licence, was aged 71, and had 620 hours total flying experience (351 on type), with 19 hours in the last 90 days and 6 hours in the last 28 days.
G-PETS was being operated as a Commercial Air Transport (non-revenue) flight with one pilot on board. The commander held an Airline Transport Pilot's Licence, was aged 53, and had 6,471 hours total flying experience (213 on type), with 62 hours in the last 90 days and 41 hours in the last 28 days.
Events Leading to the Incident
G-BTMR flew into Bagby Airfield with two pilots and landed on Runway 24. After parking in the maintenance area on the north side of the airfield, the pilots reboarded the aircraft about three hours later, swapping seats and changing over headsets. They then taxied for a departure from Runway 24. The commander, in the right seat, operated the radio. Unable to obtain a radio check on the A/G frequency, he made a blind call advising that they were backtracking along Runway 24. He received no reply and heard no other radio transmissions.
Before crossing the main runway from north to south, both pilots looked for traffic on Runway 06 but saw none. G-BTMR crossed the runway, made a short backtrack, and vacated onto a parallel taxiway on the south side. After travelling about 100 m along the taxiway towards the Runway 24 threshold, both pilots were surprised to see G-PETS landing on Runway 06.
The Incident
At 1215 UTC, G-PETS was landing on Runway 06. Approximately 50 m into the ground roll at an airspeed of about 60 kt, the pilot observed G-BTMR enter the runway from the north side at a 45° angle away from the runway direction. G-BTMR then taxied along the runway, away from G-PETS, before vacating onto the taxiway on the south side. The pilot of G-PETS applied maximum braking and attempted to call the other aircraft but received no response. He estimated the minimum separation between the aircraft was between 50 m and 75 m. The pilot reported making standard joining and circuit radio calls on the Bagby A/G frequency during the approach to land, and had the aircraft's landing, taxi, and strobe lights on.
Aftermath and Findings
The crew of G-BTMR were unaware of the landing aircraft until it drew level with them. They then checked their headset connections and recycled the radio, establishing contact with the crew of G-PETS. No injuries were sustained by any persons on either aircraft, and neither aircraft sustained damage.
The commander of G-BTMR later considered that the lack of response to his radio calls and the expectation that Runway 24 was in use (as it had been earlier) contributed to their failure to see the DA 42. The investigation noted that G-PETS was likely already at a very low level, if not on the ground, when the pilots of G-BTMR looked towards it, and may have been obscured by the sloping terrain or part of their own aircraft structure.