Iranian investigators probing a tail-strike involving an ATR 72-600 have disclosed that a pilot under instruction was part of the cockpit crew at the time.

Sixty-three passengers and eight crew members were on board the Iran Air aircraft, identified by the Iranian Civil Aviation Organisation as EP-ITD, when the incident occurred on 26 August.

The aircraft was one of a batch of four initial deliveries to the flag-carrier in May 2017, part of a larger order for 20 of the turboprop type placed after US sanctions on the Iranian government were briefly eased.

It had departed Rasht at 14:45, bound for Tehran Mehrabad as flight IR3332, and arrived at around 15:40.

But during the landing, says the CAO, it experienced an "inappropriate" touchdown and sustained a tail-strike. The aircraft moved to the apron and the passengers disembarked, without injury.

"Afterwards the aircraft was attended by technical personnel and it was determined that it had been involved in an accident," says the CAO.

It states that flight recorders and other documentation were preserved and the crew underwent interviews, which revealed that the crew included a pilot under training, an instructor and examiner as well as an observer.

The crew told the inquiry that the approach was stabilised down to 50ft but then the nose was pitched down and the rate of descent became "unusually high".

Despite attempts to correct the situation, the tail of the aircraft scraped the runway and caused damage to the fuselage underside.

Iran Air engineers have examined the aircraft to assess the extent of the damage, in order to determine the classification of the event.