Consumer champions Which? say hundreds of thousands of people who are eligible for compensation for flight delays are not making claims.
Using the most recent Civil Aviation Authority Punctuality data, Which? found 37 million passenger journeys to or from the UK were delayed by 15 minutes or more between June 2014 and May 2015.
In total the data shows 9,000 flights were delayed by three hours or more. Which? estimates this means around 900,000 passengers travelling on these services could be eligible to claim compensation from their airline.
However, Which? reports less than four in 10 (38%) claimed money back following a delay, which suggests the majority are missing out.
Those travelling within the European Union who are delayed by more than three hours could be entitled to up to €400 (£283 at current rates). That rises to up to €600 (£425) if the journey is over 3,500km.
The worst offenders
Which? looked at over 1.7 million flights and picked out the worst offenders that delayed passengers by three hours or more.
The worst UK airport for lengthy delayed flights was Gatwick, with 2,134 flights or 200,000 passenger journeys impacted.
Vueling, Monarch and Thomas Cook were the worst airlines for delays on short-haul flights, with over 700 delayed take-offs affecting 68,000 passenger journeys between them.
Pakistan International Airlines, Air India and American Airlines were the worst airlines on long haul journeys, accounting for 400 delayed flights and impacting 40,500 passenger trips combined.
The three largest airlines operating in the UK (Easyjet, BA and Ryanair) were responsible for 40% of delays over three hours. However, set against the proportion of flights each operate they achieved the industry average.
How to claim compensation
You need to apply to your airline or tour operator in the first instance.
If the airline can claim that the delay was down to ‘extraordinary circumstances’ (such as a security risk, weather event, dust cloud – things beyond the airline’s control) then you don’t have a claim. Note that recent rulings concluded this term does not include mechanical failure of the plane.
If you think the airline is not being fair about what counts as extraordinary circumstances then you can challenge it. If your flight was cancelled or delayed in the UK then you can raise it with the Civil Aviation Authority.