The accident aircraft Boeing 737-3Y0 EI-DON, was operated by KD Avia on a flight from Kaliningrad, Russia to Barcelona, Spain and return. Flight KD793 to Barcelona was uneventful. The return flight, KD794, departed at 16:18 with 138 passengers and six crew members on board. The copilot was Pilot Flying, the captain was Pilot Monitoring. The en route part of the flight was uneventful. As the flight was descending to Kaliningrad at night in heavy rains and with gusty crosswind. During the descent flaps were first selected at 1ø and thereafter to 5ø. As the flaps were transitioning to this position, a flap asymmetry warning caught the attention of the crew. At 19:00 hours the captain took over control and selected flaps to 2ø, the position at which there was no asymmetry warning. The crew then contacted the controller at Kaliningrad and reported that they had flap problems. As the descent was continued, the copilot performed the necessary calculations for a landing with flaps at 2ø. At 19:09 the cabin crew was warned to prepare for a high-speed landing. Using the QRH to work the flap issue, the co-pilot activated the ‘flap inhibit’ and ‘gear inhibit’ switches. This “incorrect” action effectively disconnected the ground-proximity warning system (GPWS). At 19:11 it was established that the landing speed would be Vref +30, leading to a planned landing speed of 161 knots. At 19:14 the Landing Gear Warning Horn sounded due to the combination of power and flaps setting with the fact that the landing gear had not been selected down. This warning was cancelled by the crew. When the engine power was reduced to idle, the Landing Gear Warning Horn sounded again. This time the crew did not pay attention to the warning and continued to land. The airplane performed a gear up landing, sliding for 1440 m before coming to rest on the runway. The flap asymmetry issue was caused by a faulty Flap Position Transmitter. The flaps had extended to the commanded position, but the system incorrectly detected an asymmetry issue. This issue had occurred previously on EI-DON. The sensor had been replaced prior to departure from Kaliningrad that same day. CAUSE (translated from Russian): The cause of the accident was landing the aircraft with landing gear retracted, leading to structural damage to the airplane and engines, and this was due to a combination of the following adverse factors: – the erroneous action of the second pilot to switch of the GPWS, which was the result of incorrect execution of the recommendations in the QRH to disable the alarm when a flap asymmetry occurs; – the presence on board the aircraft Boeing-737-300 EI-DON collection QRH, contained in paragraph Additional Deferred Item head Trailing Edge Flap Asymmetry, recommendations crew who are not specialized for a particular board layout; – mistaken switching off by co-pilot the landing gear warning of ground proximity warning system (GPWS), that resulted from incorrect carrying out of the recommendations of Quick Reference Handbook (QRH) in part of switching off the trailing edge flap warning in case of asymmetrical extension. – QRH availability on board of Boeing-737-300 EI-DON that contained in the Additional Deferred Item paragraph of the Trailing Edge Flap Asymmetry article the recommendations for crew team that were not particularized for the certain aircraft configuration. – violation of the “Flight Crew Manual of the aircraft Boeing 737-300” and failure to comply with the QRH (section LANDING CHECKLIST), with the result that the crew did not deploy the undercarriage and did not control their position; – the preconceived notion of the crew that Landing Gear Warning Horn audio alarm (alarm about the landing gear when the flaps are being selected) was a false warning during landing, causing the crew to repeatedly cut off the alarm without a checkng the position of the landing gear; – poor crew interaction, as expressed in the absence of monitoring the compliance with FCOM and QRH, the origin and development of the particular situation.