Two Boeing 737-800 passenger aircraft, operated by Ryanair, were involved in a taxiway collision at London-Stansted Airport (STN), England. Ryanair flight 752, operated by EI-ENL, had landed on runway 22 at London-Stansted Airport following a flight from Hahn Airport, Germany. It was a dry morning, visibility was good, and the wind was from 230ø at 5 kt. After vacating the runway via the high speed link NR the co-pilot checked in on the Ground radio frequency and the aircraft was instructed to take the second left turning onto Taxiway J and to hold short of Taxiway C. Later the Ground controller instructed EI-ENL to proceed via the ‘C West’ line to park on Stand 43R. As EI-ENL was taxiing, another aircraft, Ryanair flight 1021 to Warsaw, Poland, operated by EI-DLJ, requested permission to “push and start” from Stand 44R. The Ground controller approved this request and in so doing repeated the stand number clearly and instructed EI-DLJ to push onto the ‘C West’ line. The crew of EI-ENL did not discern that another aircraft was being given a pushback instruction that conflicted with their own routing. Onboard EI-DLJ, the crew were completing their pre-flight preparations and therefore they were not monitoring taxi instructions given on the Ground frequency when EI-ENL received parking instructions. When the tug driver for E-DLJ was passed the ‘brakes released’ signal, he saw EI-ENL on Taxiway J but lost contact with it as he started the pushback. A pier obscured the controller’s view of Stands 43 and 44 and only the fins of aircraft on the ‘C West’ line could be seen. The crew of EI-ENL saw a B737 on Stand 44R as they turned onto the ‘C West’ line but they did not appreciate that it was commencing pushback. After completing the turn, the co-pilot looked to his right and realised that the tail cone of the other B737, was now moving towards him. He told the commander to stop and the commander started to turn left, away from the conflict, and to apply the brakes. Three and a half seconds after the co-pilot started speaking, the right hand winglet of EI-ENL impacted the leading edge of the right horizontal stabiliser on EI-DLJ. The winglet was forced under the tail cone of EI-DLJ where it penetrated the APU bay and fragmented. The pilots of EI-ENL felt the aircraft “touch” before they brought it to a halt a few metres further on. The tug driver had seen EI-ENL re-appear behind EI-DLJ and braked hard but could not prevent the collision. The impact of the winglet caused the APU on EI-DLJ to fail and a small amount of fuel to leak onto the ground. Onboard, the crew felt a thump, the aircraft stopped suddenly and some electrical services failed. After engines had been shut down the two 737s were later towed onto their respective stands and all persons onboard disembarked without injury.