Northern Isles MP Alistair Carmichael has called on the aviation minister to look into serious safety concerns raised by Loganair pilots.
The former Scottish secretary said communities in the Highlands and Islands needed to have “full confidence” in the “lifeline services”.
He highlighted the issue during transport questions in the House of Commons yesterday.
Mr Carmichael told MPs that pilots union Balpa had written to the management of Loganair about cases of aircraft being returned to the line “despite being unserviceable”.
They claim some planes have defects affecting safety, while others are placed under restrictions that render them “effectively unusable”.
The Orkney and Shetland MP added: “These are lifeline services to some of the most economically fragile communities in the country.
“What can you do to ensure – either through your department or the Civil Aviation Authority (CAA) – our local communities can retain full confidence in these crucial services?”
Aviation minister Robert Goodwill insisted safety was the UK Government’s “top priority” and that all airlines have to meet strict safety maintenance requirements.
He added: “Compliance with these requirements is overseen by the CAA.
“I understand the CAA is aware of Loganair’s recent difficulties, but is satisfied the company is operating safely and maintaining its aircraft in accordance with the necessary safety requirements.
“This matter will of course be kept under review.”
The letter from Balpa’s company council was sent to Loganair chief executive Stewart Adams last week.
It follows a two-page letter which outlined major concerns pilots have about Loganair’s engineering department.
Mr Adams told the Press and Journal earlier this week the safety of passengers and staff “is and will always be our number one priority”.
He also said none of his pilots – in whose hands the final decision on whether to depart rests – would ever leave the ground with safety concerns.
Last night Mr Carmichael said: “This, I hope, will give some confidence to local people and visitors that air services within the Highlands and islands are safe but need more effort to improve reliability.”