A DELAYED plane carrying 33 passengers took off from Orkney after air traffic controllers had gone home, it has emerged.

The scheduled Loganair flight left Kirkwall for Edinburgh after the airport’s tower had closed amid a work-to-rule dispute.

A whistleblower said the plane was only able to get off the ground after a ground crew member entered the tower and switched on the runway lights. The incident, last Friday night, is now being investigated by the Civil Aviation Authority (CAA).

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Both Highlands and Islands Airports Ltd (HIAL), which operates Kirkwall Airport, and Loganair have said that there was no breach of either rules or aircraft safety and that both companies were investigating the circumstances of the flight, where air traffic controllers would normally be monitoring activities.

HIAL’s air traffic controllers are working to rule – including not staying beyond airport opening hours if a plane is delayed – because of a pay dispute.

The plane, which was carrying three crew as well as its passengers, took off at 8.45pm, an hour behind schedule and 45 minutes after controllers clocked off.

The whistleblower said that the airport was closed and therefore legally unlicensed and that no commercial aircraft could operate from an unlicensed airport without CAA approval.

The incident triggered mutual accusations of intransigence on the part of HIAL and that the aircraft controllers had exceeded the legal bounds of their agreed industrial action.

Orkney and Shetland MP Alistair Carmichael said he had written to the CAA demanding an investigation as only a thorough probe of events could get to the truth of what happened.

Mr Carmichael added: “I am very concerned about the content of what I have been told and want an early answer from the CAA about what they intend to do as the regulator of this area. It obviously concerns me because the safety of the people travelling throughout the Highlands and Islands is absolutely paramount and, on the face of it, this is a very serious breach of the proper procedures.”

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The disagreement between HIAL and the air traffic controllers union Prospect hinges on the hours that should have been covered, with HIAL and Loganair claiming the controllers were rostered till 8.30pm and the controllers saying their hours concluded at 8.00pm.

A spokesman for HIAL said that the decision to carry on with the flight had been an operational one, with ground management and the pilot deciding it was safe to fly.

He said: “The flight was able to depart following a dynamic risk assessment undertaken by Loganair’s flight operations management in conjunction with HIAL. Recognised safety procedures were followed before the aircraft departed safely and completed its schedule to Edinburgh.”

A spokesman for Loganair said that the plane departed “using alternative procedures available to pilots to fly without local air traffic control support at Kirkwall.”

The CAA, meanwhile, confirmed the organisation was aware of the incident adding that it was “currently looking into the circumstances.”

Prospect negotiations officer David Avery said it would be wrong to comment on the specifics of the incident while an investigation was ongoing.

He added: “If a flight with passengers has departed without air traffic control that would be very serious and the CAA would need to look into the matter urgently..”

Loganair managing director Jonathan Hinkles said Friday evening’s actions were “beyond the scope of the dispute notified by Prospect”.

He also thanked the HIAL safety teams and Loganair’s crew for ensuring customers complete their planned flight despite the “unforeseen and unnecessary” turn of events. Loganair said it notified the CAA after the event as it was an “unusual circumstance” but all parties were “satisfied that the operation was safe and legal.”