What are the rules?These aren't willy-nilly have a delay, get compensation rules - there are important qualifiers. Here's a quick summary below. See Martin's full Flight Delay Compensation help with free template letters for more.CHAR(13) + CHAR(10)It's only for EU flights. You must be on a plane that left from an EU airport, or arrived at an EU airport (but then it must be an EU airline).You can go back to 2008. This doesn't just apply to recent flights. If you've been delayed at any time since 2005, you have a right to compensation under EU rules. Though in the UK, it's much easier in practice if it's been since 2008 due to our legal system.It must have been the airline's fault to claim. The delay has to be under the airline's control. Staffing problems, poor planning, and even technical problems caused by not fixing regular wear and tear all count. Political unrest or bad weather don't.Delays must be over three hours to get compensation. This is a straight rule, although it's about when you arrive, not when you leave. So if you're on a flight that takes off 4 hours late but arrives 2 hours 55minutes late - you're not over the three hours needed to get compensation. If you're struggling to remember if your delay passed the crucial three hour cusp, try the FlightStats website. It's a free site, though you need to register to use it. It's worth noting the site's terms and conditions say it can't be used in any passenger rights claims actions, so best to consider it a belt and braces check that your memory of the event is correct.Compensation depends on delay, not flight cost. The amount you get is fixed solely on the flight length and delay time. So a 1,000km flight delayed by four hours is €250 (£200ish) per person, while a 4,000km flight delayed for five hours is €600 (£480ish) per person.How do I claim?First, write to the airline stating the details of your delay and asking for the compensation. If you're unsuccessful, depending on where you flew from and the airline you flew with, go to the Civil Aviation Authority, the European Consumer Centre, or the relevant regulator to get a ruling. However as these aren't ombudsman schemes, their decisions, which should help to push the airline into paying up, aren't binding.When you do reclaim, many people get paid out easily, such as Samantha. She emailed me saying: "We were delayed over three hours on our Easyjet flight back from Palma to Stansted in June due to a lack of crew. I sent the letter on 16 July, had an e-mail reply two days later agreeing to our claim and €500 was refunded to our card yesterday (5 August)." CHAR(13) + CHAR(10) CHAR(13) + CHAR(10)Bryan also had success with Easyjet. He emailed me saying: "My wife and I were delayed for five hours on a July flight from Edinburgh to Belfast. Used your templates and received 500 Euros from Easyjet in compensation." CHAR(13) + CHAR(10) CHAR(13) + CHAR(10)But others meet a brick wall - few are in the middle - often because of two court cases...What if my claim's affected by on-going court cases?Two major airlines - Thomson and Jet2 - have been fighting two specific elements of the flight delay rules in court and they, and a few other airlines, have put relevant cases on hold while they await the outcome of their respective bids to make appeals to the Supreme Court.The Jet2 case is all about what is defined as being the airlines fault. It argued that unexpected technical faults are extraordinary, meaning airlines don't need to payout, but the Court of Appeal ruled that airlines can only cite technical faults as a reason for not paying compensation if the fault was originally caused by an event that was "out of the ordinary".Meanwhile the Thomson case saw the airline argue that you can't claim for flight delays and cancellations that are more than two years old. Again the Court of Appeal ruled against this and said you can claim for flights delays and cancellations that took place over two years ago.But despite the airlines currently petitioning against the Court of Appeal's rulings, it's still worth submitting new claims and asking for old claims to be reopened from when they were put on hold pending the Court of Appeal judgment. You never know... and nothing is lost by trying.Is this fair on the airlines?I don't want to push unnecessary compensation culture. For someone on a £10 flight, only just three hours delayed, which didn't bother them, it's worth questioning whether it's fair to push for £200. I'd urge caution or it'll push up all our air fares.Yet if you're a family with young kids who spent 24 hours in a smelly airport lounge with kids sleeping on the seats - then push for your rights. Each individual must make their own ethical choice of whether to take up the cudgels.