Operators of a plane that skidded off the runway at Sumburgh said they were “intrigued” as to what went wrong.
The two pilots escaped uninjured when the Dornier 328 came to a halt on the grass on Thursday as it landed at the end of a routine training exercise.
There were no passengers on board.
Commentators on social media instantly pointed at the strong crosswinds as the most likely cause for the aircraft to come off the runway.
But Dave Jackson, the managing director of 328 Support Services, said the company was carrying out training flights at Sumburgh because of those winds.
He said the Bavaria-based company was regularly carrying out “calibration flights” in the north of Scotland, including Shetland.
He said: “We were doing some calibration flights, and we needed the high winds in order to do our calibration testing. That’s why we were in Shetland.
“We have been to Shetland two or three times and I am afraid to say this is the first time we had an incident.
“We are all intrigued, because these flights are something that we do as part of our business.”
The two test pilots were said to be very experienced with several thousands hours of flying the Dornier 328 aircraft.
Mr Jackson said he didn’t know what went wrong and had to wait for the results of an investigation by the Air Accident Investigation Branch.