A British Airways co-pilot suffered significant eye damage when a laser was shone into the cockpit of a plane landing at Heathrow Airport, a trade union has revealed.
Jim McAuslan, general secretary of the British Airline Pilots Association (Balpa), said a "military strength" device was used, causing the most serious injury ever inflicted upon a pilot in the UK during a laser attack.
"His retina was burnt on one of his eyes," Mr McAuslan said.
He added that "people have assumed (the laser) must have been military strength" because the damage was much more severe than that caused by common laser pens.
He said: "When there's something like this, that's damaged a man's retina, that starts to worry us."
Mr McAuslan said the victim was a co-pilot at the time of the incident and was not operating the plane.
He was taken to a hospital in Sheffield for treatment and has not been back to work following the attack, which took place in the spring.
Mr McAuslan did not reveal the identity of the victim as the case is "under an employment tribunal".
Balpa has found that half of pilots experienced a laser attack in the past 12 months.
Figures from the Civil Aviation Authority (CAA) show more laser incidents were reported at Heathrow than at any other airport in the UK this year.
The west London hub had 48 attacks in the first six months of the year. Some 168 were recorded in 2014.
BA issued a statement which read: "The safety of our crew and our customers is always our main concern.
"We urge our pilots to report such incidents so we can make the authorities aware."