What Are The Top 10 Causes of Flight Delays?

Flight delays - arguably the most common cause of frustration for air passengers all over the world. In the last few years the number of delayed flights has grown with nearly every 3rd flight departing with more than 15 minutes late. Your plane could remain grounded for various reasons, and while some of them are beyond the airlines’ control, others lie within their responsibility and could bring you financial compensation of up to £502 (€600) under EU Regulation 261/2004. 

Why do flights get delayed? Let’s find out.

What are common reasons for flight delays?

Understanding the reasons behind disrupted flight departures can help you better prepare for any legal disputes that might arise from your flight disruption and increase your chances for reimbursement. Based on information from Eurocontrol and the Bureau of Transportation Statistics (BTS), we at SkyRefund summarized the ten most common causes of flight delays.

 

1. Adverse weather conditions

The most common plane delay reason is probably the first to come to mind for many of us. Bad weather – from heavy rain to blizzards, through fog and strong wind, almost always creates chaos at airports and could collaterally affect many flights down the schedule. According yo Eurocontrol's research on flight delays, weather-related issues added 1.2 minutes on average per departing plane. 

EU261 lists bad weather under the so-called extraordinary circumstances and excludes flights affected by meteorological conditions from eligibility for compensation. However, airlines tend to misuse this excuse and apply it even when the causes of delay are within their control, to avoid paying compensation. 

Expert tip: If you suspect the air carrier is using the weather conditions simply as a blanket excuse, you have the right to challenge the explanation for the delay and request evidence such as the meteorological report from the day of your flight. If you submit your claim with SkyRefund, our aviation lawyers will handle such disputes without involving you in the tedious and sometimes exhausting legal process. 

 

2. Security and customs checks

Flying through big busy airports comes with perks like numerous shopping and dining options and luxurious lounges –  but also carries risks for your smooth travel experience. Long security, passport, and customs check queues are to be expected at air hubs with heavy passenger traffic and could potentially lead to flight delays or missed connections. 

While this factor accounts for a small fraction of total delay minutes according to BTS, it shouldn’t be underestimated, especially during peak holiday seasons like Christmas, Easter and summertime. In cases like this, however, airlines are not held accountable and you wouldn’t be entitled to compensation. We recommend you be at the airport as early as possible to avoid unnecessary rush and stress.

 

3. Previously delayed flight

Ever wonder how many flights a single aircraft could make per day? Typically, one airplane can operate 6 to 8 short-haul flights or 3 to 5 medium-haul flights within 24 hours. Eurocontrol found that knock-on effects delay flights with 8.2 minutes on average. With that in mind, it is easy to imagine how a delay early in the schedule could affect all other flights down the line.  

For the purposes of compensation claim evaluations, each flight is assessed separately and the airline is required to provide the exact reason for each delay. Under EU261, you would be entitled to reimbursement only if the reason was within the airline’s control, and examples of that would be crew scheduling issues, cabin cleaning or catering delays (see section 6), and aircraft technical maintenance. If you are uncertain whether your flight qualifies for compensation, consult our free flight delay compensation calculator.

Expert tip: When booking your tickets, consider flying early in the morning (between 6 and 9 a.m.). This could significantly decrease your chance of experiencing a delay. 

 

4. Strikes

Another common issue at major airports is staff strikes that block the operations of entire air hubs, sometimes for days at a time. While these are usually announced in advance and more often lead to cancellations than delays, some flights may still operate but with significant schedule disruptions. 

EU Regulation 261/2004 explicitly lists industrial action as an exception of its provisions, so flights affected by such strikes will not qualify for compensation. On the other hand, if the airline personnel goes on strike (a.k.a. wildcat strike) and your flight gets delayed, you will be entitled to compensation. 

 

5. Air Traffic Control (ACT) restrictions

The next answer to the question “why are flights delayed?” lies with Air Traffic Control. Experts in control towers regulate airport traffic and no plane can take off without their clearance. Airport or airspace congestion, especially at busy hubs, often causes delays, as ATC assigns specific departure slots to ensure safety.
EU261 considers ATC restrictions an extraordinary circumstance and airlines may use this excuse, even when the delay was actually caused by factors within their control and they missed their assigned slot.  

Expert tip: Even if you think your chances for compensation are slim, do not leave the airport without proof of delay. Take photos of the departure board, save all flight notifications, and ask airline staff for written confirmation of the delay reason.

 

6. Baggage loading 

Take-off depends not only on the successful boarding of passengers but also on the timely loading of checked luggage. During and post the Covid era, many airports had to lay their employees off, especially the ones involved in ground operations, and these staff shortages continue to affect flight schedules to this day. 

Even if baggage loading is usually operated by third-party ground handling services, the airline would be liable in case of any disruptions to this process, and if the crew cites this reason for the delay, you should make sure to record it as proof for your claim.

 

7. Cabin cleaning and catering 

Services like cabin cleaning in between flights and catering for in-flight meals are typically also outsourced to third-party companies, often associated with the airport. However, a flight disruption caused by delays in the delivery of these services is considered the airline’s responsibility under EU261 and you should be wary if you are told otherwise.

Expert tip: A delay of more than 3 hours for these reasons would be a rare exception, but you could reserve your right to care. If you are stuck at the gate or in the aircraft itself, do not hesitate to approach the airline’s staff about it. 

 

8. Technical issues with the aircraft

Even if most airplanes nowadays mostly rely on automatized and electronic systems, technical and mechanical issues occur from time to time, possibly causing delays or even cancellations. If your flight gets delayed because the aircraft needs repairs and you arrive at your final destination more than 3 hours later than originally planned, you will be entitled to compensation from the airline. EU261 considers it the airline's responsibility to maintain its fleet in a good condition and to perform regular check-ups of its aircraft. 

 

9. Passenger-related incidents

Sometimes, a single passenger could cause a delayed departure or even a diversion. For example, most airlines are tolerant toward travellers with connecting flights (under the same booking) and do everything possible to put them on their next flight. It’s not uncommon for everyone to be on board, ready to depart, but waiting for that one passenger rushing through the airport to catch the next leg of his journey. Typically, however, such delays are insignificant.

A more dramatic example is a medical emergency where the duration of the delay is unpredictable. If someone feels unwell before take-off, the crew is obliged to wait for the medics. An emergency that occurs mid-flight could cause the pilots to divert the plane and either return to their departure point or land elsewhere. 

Another reason for a flight delay could be an unruly passenger, threatening the safety of his fellow travellers and the airline crew. These incidents are on the rise and flights usually get diverted until such individuals are removed and detained by local authorities. Unfortunately, as unpleasant as these situations are, airlines are not held accountable and do not owe compensation. 

 

10. Security threats

Anonymous tips for terrorist attacks, bomb threats, suspicious individuals… the list of potential security threats that airport staff and police officers have to look out for is long. Such cases could turn out to be a false alarm like for example a bag forgotten by a distracted traveller. 

 However, all potential safety threats are taken seriously, even if this means airport chaos, including flight delays or cancellations. Preventing serious incidents is always the priority. Under EU261, security threats are classified as extraordinary circumstances and airlines are not obliged to compensate passengers in such cases. 

 

How can SkyRefund help?

EU Regulation 261/2004 states that you may be entitled to compensation of up to £502 (€600) for a delayed flight. Airlines often try to attribute delays to extraordinary circumstances in order to avoid paying you and here is where SkyRefund’s expertise could come to the rescue. Our aviation law specialists are well acquainted with air carriers’ tendency to find loopholes and excellently prepared to fight for your rights. 

We have helped more than 700 000 passengers successfully claim their compensation payments not only for delayed flights, but also for flight cancellations, denied boardings, and downgrading. You can use our free compensation calculator to establish your right to compensation and leave the rest to us. 

 

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