A Virgin Atlantic flight to New York has been forced to return to London's Heathrow Airport after a laser beam was pointed at the plane - prompting urgent action in the cockpit.
Audio of the plane's exchange with air traffic control describes one of the pilots having a "medical issue" following the incident, which occurred "six or seven miles" west of Heathrow.
Virgin confirmed Flight VS025 to JFK had been abandoned as a "precautionary measure" after the plane's First Officer reported "feeling unwell".
All the passengers on the flight - which took off just before 8.00pm - are safe, but they will have to wait until 1pm on Monday to continue their journey because of "limited availability".
Angry travellers complained that their luggage was going to remain on the plane overnight.
One passenger said there was "very little compassion" at Heathrow and accused the airline of "doing a poor job of looking after people".
A spokesperson for Virgin Atlantic USA: "The safety of our crew and customers is our top priority and we apologise for any inconvenience to those onboard".
"All customers will be offered overnight accommodation and we will get them on their journey as soon as possible".
The airline said it is working with authorities to identify the source of the "laser beam incident".
This recording to air traffic control about the incident was obtained by LiveATC.net:
British Metropolitan Police said they had been contacted at around 9.35pm but were still trying to establish where the offence took place.
Police have previously warned over high-powered laser pens being aimed at aircraft, saying there could be "disastrous consequences" through disorientation or momentary loss of control.
A spokesperson for the UK's Civil Aviation Authority said: "Shining a laser at an aircraft in flight could pose a serious safety risk and it is a criminal offence to do so".
"We strongly urge anyone who sees a laser being used at night in the vicinity of an airport to contact the police immediately".
In 2014, a man who was caught on camera laughing with friends as he dazzled a police helicopter over Birmingham escaped jail after he admitted the offence.