Top 15 top reasons why flights are delayed: from bad weather and waiting for luggage to strikes, bird collisions and crew tardiness

So, you are at the airport waiting for your departure, but your flight is suddenly delayed. This is certainly not a funny situation at all, but it's common enough to be surprised by what has happened. And the first thing you wonder is: why is my flight delayed?

Flight cancelations and delays are such a familiar part of air travel as airport security screening. But the preconditions for this can be a variety of situations and circumstances. In this article, we'll look at 15 of the most common causes of flight delays.

Why are flights delayed?

There are many possibilities. Flight management is a very complex process on many different levels. There are factors that are controlled directly by the carrier, such as aircraft turnover between flights, technical availability, passenger punctuality, crew performance, etc. But there are also many factors over which the airline has no control: weather, security, airport conditions and environment, air traffic control, and so on.

So the question of why a flight is delayed will arise as long as airplanes fly, and there is no way to avoid it. For example, in the past year 2023, about 20.83% of all flights were delayed by 15 minutes or more, making it the highest in the past 9 years.

The most common reasons for flight delays are

1. Air traffic control restrictions

Air passenger traffic has increased at a formidable rate since the 80s, from half a billion passengers a year to three billion. There are many planes in the sky at any given moment, and most of the traffic is concentrated in a few transportation hubs such as New York, London, Paris, etc.

Longer-haul flights face a lot of restrictions that force airlines to make last-minute changes. In addition, some parts of the world do not have the same radar coverage as the US or Europe. Therefore, air traffic controllers are forced to increase the time between landings and takeoffs to ensure safety, which in a chain of events leads to the delay of one or more flights.

If a flight is canceled or delayed due to air traffic restrictions, the passenger will not be able to get compensation for it, as airlines are obliged to abide by air traffic control decisions.

2. Bad weather conditions

Mother Nature does not always favor travelers and often plays a major role in flight delays. Adverse weather conditions are one of the main causes of flight delays, but not as common as one might think. Indeed, it is mostly extreme weather conditions such as blizzards, hurricanes, tornadoes, etc. that can delay an airplane, and this accounts for only 6% of all delays.

Often airlines may cite bad weather as the reason for flight delays, although this is not actually the case. To check if your flight is really delayed due to bad weather, you can look at what are called METAR bulletins, which are weather reports used in aviation.

3. Collisions with birds

It seems unbelievable, but the reason why airplanes are delayed can be even a single bird. And it's not that uncommon: in the United States alone, an average of about 13,000 bird collisions occur each year.

Most of them occur during landing and takeoff. While they don't usually cause much damage, they are still considered a safety hazard, with protocols requiring a number of procedures to be followed after a collision.

The European Court of Justice has defined a collision with birds as an extraordinary circumstance, so there is no compensation to be paid to the passenger for flight delays due to this cause.

4. Domino effect

One delayed flight can start a domino effect on the entire subsequent schedule. It causes a phenomenon such as jet lag, where a flight cannot depart on time due to the late arrival of the airplane.

As for compensation, collateral effects do not relieve the carrier of such liability to passengers. But a claim can be denied on the basis of a domino effect if the cause of the delay was an extraordinary circumstance with a limitation within 24 hours of the original event. Simply put, if you are scheduled to fly on Friday on an airplane that collided with a bird on Monday and that affected its entire future schedule, the airline cannot deny your claim based on the domino effect.

5. Strikes

Airline employee strikes are also one of the main reasons why airplanes are delayed. They can either have minimal impact or they can undermine business and trigger huge costs. For example, British Airways pilots' 48-hour strike in 2019 affected hundreds of thousands of passengers because of the 48-hour strike. For them, these strikes are incomprehensible and rightly cause resentment.

A strike is an extraordinary circumstance, so there is no compensation for the passenger. But be careful if the carrier refers to this reason, although the flight does not fall within its period.

6. Waiting for passengers from connecting flights

As a rule, carriers do not wait for connecting passengers. But in certain cases, they may slightly delay a flight. For example, if it doesn't affect other passengers who might miss the connecting flight. Or if the bags of passengers who need to wait are already loaded on the plane, and unloading them will take longer than waiting to board.

It is almost impossible to get compensation because of a flight delay for such a reason, as airlines do not wait long enough for passengers to have sufficient reason to do so.

7. Waiting for baggage

If baggage is delayed in transit and many passengers are affected, the airline may delay the flight. This decision is also made on a case-by-case basis. But a long delay in this case is unlikely. And just as with waiting for connecting passengers, the air carrier will not wait long enough to allow passengers to then apply for compensation.

8. Waiting for cargo

Apart from passengers and their baggage, commercial airlines also carry a variety of cargo, which brings them between 5% and 10% of their total revenue. Therefore, late arrival of cargo can also delay departure. Naturally, we are not talking about a serious delay of 4 hours, but about a slight deviation from the schedule. And, accordingly, we are also not talking about financial compensation for passengers.

9. Missing crew

Not only passengers, but also crew members can miss a flight, for example, being stuck in traffic. The airplane cannot take off if the required number of crew (approximately 1 flight attendant per 50 seats) is not present.

Therefore, the flight may be delayed, and this is not that uncommon. Generally, airlines in hubs or busy airports like London or Paris usually have crew on staff. But there are situations where a crew has to come from another destination.

A flight delay due to lack of crew can reach several hours, and since such a situation is within the company's area of responsibility, the passenger can claim compensation.

10. Need for rest for flight crew

The top 10 reasons for flight delays also include the need for a break for the flight crew. Pilots and flight attendants need certain periods of time to rest, which can trigger some staffing issues. Due to schedule disruptions and delayed rotations, the crew may exhaust their rest hours. In such a case, if the carrier does not have a replacement, there is a possibility of flight delays.

These circumstances are within the air carrier's control, so the passenger can claim compensation.

11. waiting for catering

This is a reason many people don't immediately think of, but catering delivery (food, utensils, hygiene items, etc.) can also be something that will cause flight delays.

A catering agent is responsible for all phases of the job: loading and unloading supplies and equipment, managing inventory, driving catering trucks, etc. But because of the large amount of movement, things don't always go according to plan.

Since the catering agent is hired by the airline, the airline is also responsible for his services. Therefore, if the flight is delayed for this reason, the passenger may apply for compensation.

12. Waiting for clearance

Before the airplane engines are started, there are many events and activities that determine whether the airplane will take off on time. Fulfilling all of these requirements is done according to safety protocols. Factors affecting this may or may not be influenced by the airline, which ultimately affects the ability to receive compensation.

13. Aircraft Preparation

This process begins as soon as the plane lands and involves many steps, from connecting the plane to the ground power system to cleaning toilets and refueling. They can also cause flight delays, including (though extremely rare) several hours. It is the airline's responsibility to keep the fleet in flying condition, so they are also responsible for delays.

14. Technical and mechanical problems

Technical problems are a fairly common cause of flight delays, and although it sounds scary, in most cases they are quickly repaired and are not dangerous for passengers. They are mostly problems with aircraft parking, water drainage system in winter, engine fan blades, air conditioning or fuel contamination.

Usually a passenger can be compensated for a delay due to technical reasons, unless it is a manufacturing defect for which the airline is not responsible.

15. Weight restrictions

The maximum takeoff weight (MTOW) is defined for each airplane. It includes the total weight of cargo, passengers, baggage, food, fuel, etc. Interestingly, this number is not constant: it depends on atmospheric conditions, altitude. If the weight is exceeded, the airplane cannot take off. This is also left to the airline's control, so passengers are compensated due to flight delays.

Apart from these 15 main reasons for flight delays, there are other less frequent ones, such as problems with the coffee machine on the plane or undisciplined passengers who interfere with the flight. But some pretty funny episodes happen, too. For example, turtles going to lay eggs in Jamaica Bay sometimes pass through U.S. airports. In 2016, more than 500 turtles were moved from the runways of JFK airport to a natural habitat. Of course, you won't be compensated for such a delay, but a funny travel story will stay with you.