A helicopter pilot was forced to make a crash-landing at City of Derry airport on Sunday.
It happened at the airfield shortly before 1700 BST. The pilot was said to be qualified, but was taking a refresher course.
Airport manager Damien Tierney said the helicopter was 20 feet above the ground when the pilot lost control.
No-one was injured, but the pilot was treated for shock and minor cuts and bruising following the incident.
"The aircraft hit the ground quite hard, sustaining a substantial amount of damage to the aircraft. But the pilot fortunately was able to walk away with just minor injuries," Mr Tierney said.
"He is quite shaken up obviously, but he is fine."
The pilot was the only person in the helicopter.
The runway was closed for 40 minutes as staff made sure there was no debris on the ground.