Pilots had to request a priority landing at Glasgow Airport as a precaution due to a passenger medical issue on board a flight.
The incident involved a British Airways flight travelling from London Heathrow, which departed the capital at 7:30am this morning.
Flight tracking site Flightradar24 shows the plane descended rapidly from 31,000 ft to 11,000 ft in a matter of minutes on approach to Glasgow as it flew above Cumbria and Dumfries and Galloway.
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This came after the plane issued a Squawk 7700 emergency code - which is reserved for emergency situations and immediately alerts Air Traffic Control (ATC) and other units that the that the aircraft is in distress.
One plane tracker commented that the altitude drop would have been "terrifying for the passengers".
They tweeted: "British Airways inflight emergency. BA1472 has squawked 7700 look at the altitude drop - that has to be terrifying for the passengers - now at 11,000 ft - dropped 20,000ft in a few mins".
The flight, which was due to arrive at 8:40am, landed safely at Glasgow Airport at 08:24am.
A British Airways spokeswoman confirmed to Glasgow Live that the pilots requested a priority landing as a precaution due to a customer requiring medical assistance.
Glasgow Airport have been contacted for comment.
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