The incident has resulted in a change to safety measures around the release handles, Ritzau reported on Wednesday.
Helicopter Wing Karup, a unit of the Danish military, conducted an investigation into the accident, which occurred on June 30th when an EH-101 Merlin rescue helicopter was transporting a patient to Copenhagen's Rigshospitalet.
The door fell from a height of 150-200 metres and landed in the back yard of a property on Frederiksborggade, a busy street around 1.5 kilometres from Rigshospitalet's helicopter landing pad.
The investigation found that the release handle on the door was accidentally turned by the crew member as he removed a jacket in order to provide first aid to the patient.
“The jacket hit the release handle without anyone noticing and that cause the door to fall off. It took around 15 minutes from the turning of the handle for the door to fall because of air conditions around the helicopter,” wing commander Kim Holst, head of the investigation board at Helicopter Wing Karup, said.
It is normal practice for crew to remove the jackets in order to ensure free movement when treating patients.