There is no clear guidance on social distancing measures on an aircraft, the chief executive of Belfast City Airport has said.

Brian Ambrose was speaking following a claim social distancing measures were not observed on an Aer Lingus flight.

The airline said it was reviewing procedures on its Belfast to London flights.

Passenger Sean Mallon took photos on a Belfast-Heathrow flight, showing passengers sitting close together.

The coronavirus crisis has seen NI flights suspended, apart from two London services operating from Belfast City and City of Derry airports.

Speaking on the BBC NI's Nolan Show on Tuesday, Mr Ambrose said social distancing measures were in place in the airport but the issue arose after "the first big influx of passengers" on a flight since the pandemic.

Mr Ambrose said it was not yet clear whether the issue was inadequate measures or if people were not adhering to the measures.

"For the month of April the average loads on our flights were about 20% to 30%, so it hadn't become an issue with large volumes of people on a single flight," he said.

"Then on Monday there were 154 passengers on a 174-seater aircraft," he added.

'You cannot square this circle'

He said he had immediately been made aware of a number of "pinch points" by his operations director.

"We are putting more staff on the ground and making sure there is more compliance and customers adhere to it," he said

Mr Ambrose said there was no clear guidance on social distancing measures on an aircraft.

"It is not clear to anyone within the industry how you can ever achieve social distancing in an aircraft," he said.

"The reason the government has not been definitive is you cannot square this circle.

"You can't keep people two metres apart in an airplane.

"You are in a closed environment where there is a mixing of air."

He said even keeping the middle seat empty did not meet "two-metre" social distancing rule, which he said may be futile on an aircraft in which air is mixed.

Mr Ambrose said Monday morning and Thursday evening flights would now become busier with the reopening of the construction industry.

'Reviewing processes'

Virologist at Queen's University, Conor Bamford, said that on a plane or in an airport "close connections with people would make it very straightforward for the virus to spread".

"The virus would be spread more from talking or breathing rather than recirculation of air in a plane," he told The Nolan Show.

"We might be lucky as there is not that much virus out there In the community but it is certainly not a risk you would want to be taking at this stage," he added.

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In a statement on Monday, Aer Lingus said: "In light of the unexpectedly high loads on the Belfast – London Heathrow service this morning and the level of demand for the route, Aer Lingus is reviewing its processes and procedures applicable to the operation of this service.

"The safety and security of Aer Lingus’ customers and crew is our top priority and any process changes that are identified as being required will be implemented as a matter of urgency."