What usually happens when air passengers are told their flight is overbooked? We've been asking BBC News online readers about the incentives airlines have offered them to take later flights.
Kate Collins from Aberdeen, Scotland, says the whole cost of her holiday to Greece was covered when her flight was overbooked.
"I was on a KLM flight coming back from Greece, to Houston, Texas where I lived, with a change in Amsterdam.
"We were at the gate when one of the attendants loudly called out for volunteers to take a different flight.
"The bidding started at the gate at a few hundred dollars. When it hit over a thousand US dollars, I accepted. That was more than the cost of my entire 14-day holiday. A thousand dollars in compensation was handed to me on a pre-loaded MasterCard.
"They also gave me an overnight hotel voucher, vouchers for meals, transportation vouchers, and a seat upgrade. I was also given an overnight kit and a small clothing allowance.
"I spent the night sightseeing, and slept in comfort on the flight home."
Free flight offer
Rebecca Bell from Cambridgeshire, UK, received a free return flight to anywhere in the world.
"I was flying from Kenya to London with Virgin Atlantic, but they had overbooked.
"I was asked at check-in if I would be willing to be held back in case everyone turned up for the flight, which I agreed to. They were asking single travellers, as it is obviously easier to slot lone travellers back into empty seats than to split up groups.
"I didn't actually ask about compensation, as I wasn't in a hurry to get to London for anything in particular.
"Virgin Atlantic put me up in a hotel in Nairobi, provided transport and meal vouchers, and an upgrade to premium economy on the next day's flight.
"They then informed me that by way of compensation they would provide a free return flight to any of their worldwide destinations."
Hundreds of pounds in cash
Brian Greenhalgh who lives in Abu Dhabi, UAE, was given £600 after his flight was oversubscribed.
"We were flying from Manchester to Abu Dhabi with Etihad.
"At the check-in they asked me and my wife to check in as normal but told us they may have overbooked and asked would we consider giving up our seats and fly with Emirates to Dubai two hours later.
"We agreed and were given a voucher to get some food and a drink while we waited until the gates closed.
"On our return to the gate, they thanked me and my wife for taking the offer and rewarded us with £300 in cash and another voucher to spend in the lounge.
"But when we arrived later for the Emirates flight the gates had closed.
"We were told we would have to take a night flight and were offered another £300 for our troubles. We didn't mind at all."
Hotel and meal vouchers
Gary Holland from Devon, UK, had a good experience with United.
"The airline bumped me off an internal flight from Washington Dulles to Albany New York last year due to overbooking" he said.
"Overbooking on US internal flights is fairly common.
"I was disappointed and explained I'd just flown in from London Heathrow and was needed in Albany the next morning to attend a meeting.
"The United staff at Washington Dulles were very good in finding me an alternative flight that evening from Washington Reagan airport, and arranged a taxi to shuttle me across to that airport.
"Unfortunately the flight got cancelled due to bad weather but United staff at Washington Reagan then arranged free hotel accommodation overnight, covered meal expenses with vouchers and got me on an early flight the next morning."
By Rozina Sini, BBC's UGC and Social News Team