The actions of a Flybe crew reacting to a false emergency alarm "significantly degraded the operational capability" of the plane, a report has said.
The Air Accidents Investigation Branch said the Newquay-Edinburgh flight, made an emergency descent on 21 July.
The aircraft began to depressurize after a "spurious" smoke warning forced the crew to follow emergency protocol to remove smoke.
BBC News - Flybe criticised over Newquay-Edinburgh false alarm