A flight to Bogota returned to London Heathrow after U-turn over the sea at 37,500 feet.
Avianca flight AV121 departed London Heathrow on time at 22:05 BST Saturday night for a 10-hour flight to Bogota, Colombia.
The Boeing 787-8 (registration N783AV) climbed to 37,500 feet but turn around, still in London FIR, 30 minutes after takeoff from runway 27L.
The Dreamliner was then vectored back to LHR Airport for a reason still unknown.
Flight AV121 landed back in London, on same runway, 1 hour and 20 minutes after departure.
