Airline delays, the causes

Travel advice

London Heathrow is one of the busiest airports in the world yet it also has the honour of the worst airport delays in Europe. On average, each plane waits about half an hour before being given the clearance to take off. Quite a delay, yet it varies according to the locality and the season. Delays go up in high season departures (summer holidays and Christmas time). Jet bridges overcharged by planes, hold up at check-in, security controls and customs: all these parameters influence the punctuality of flights, as do the constant rotations or turnarounds. Turnarounds may be a familiar term for people working in air transportation, less so for the travellers. Here are some causes for delay, in decreasing order.


A plane generally returns to its departure point once arrived at destination. That is the case for domestic and long distance flights. Between landing and takeoff, there is the stopover time, which is chosen by the company. This is the time for the passengers to debark, for an aircraft ?check up' (cleaning, technical verifications) and the boarding of passengers for the following flight. If a plane is delayed upon arrival at an airport, (for one of the reasons detailed later), the stopover time, which is as short as possible for economic reasons, stops the plane from taking off on schedule. The initial delay is therefore conserved, and gets worse if other factors intervene during the rotations. Only the airline can act on delays due to rotations (which represent 29% of the delay causes), by increasing the stopover time, or by using another plane. This is possible for big companies, but less for those functioning with a reduced fleet.

Aircraft checks

This aspect, responsible for 26% of delays, consists of all the mechanical interventions made on the plane during a stopover. It includes compulsory checks, with repairs on some elements, if necessary, that concern the security of the flight (motor, cabin, cabin pressurisation), or other verifications deemed necessary by the company relating to passenger comfort (in flight entertainment, pillow cases etc). In each case, the company evaluates the time necessary for a turnaround, but has to find alternative solutions in case of a technical problem delaying an on time departure. It is important to understand the European regulations concerning passenger rights. The passenger may give up a flight and obtain compensation if the company announces a delay of at least 5 hours. When the journey includes a connection, and the 5 hour delay occurs during transit, the passenger has the right to ask the company for a return to the original port of departure. Other delays (from 2 ? 4 hours) mean passengers have the right to obtain food (drinks, sandwiches) and accommodation (night in a hotel) if the flight is delayed one day.

Airport management (safety measures)

Not to be confused with security which concerns the smooth operations of planes, safety measures aim to reduce the risk of an attack in the airport or on board. The delays due to the airport management represent 16%. They are mainly due to the reinforcement of anti-terrorism controls: Passenger and baggage controls at customs take longer when every passenger is questioned and their baggage checked. But these delays ordinarily happen during peak departure periods. Concerning authorised objects on board, the European Commission issued a regulation on the 17 October 2006.

Air Traffic Control (ATC) and passengers

They each contribute for 12% of the delays. Concerning passengers, it can be the passenger who is still shopping around in duty free shops whilst boarding is closing; another, distracted, creates an alert in the terminal by forgetting his bag; or, the most frequently observed, passengers delayed on public transport arrive just before the check-in closes. Managing those events takes time and influences the flight departure time. The delay due to ATC, rather than the flight time, concerns the landing and take-off schedule, managed by air traffic controllers that may have different priorities and orders than those of the companies.

The weather

Surprisingly, the weather does not create as much disruption as expected. Between cyclones, storms, snow storms and ice, the planet's changing weather conditions really test airport operations. Yet only 5% of the flight delays are due to climate conditions. Weather forecasts give the opportunity to cancel flights (rather than delay it) in case of unfavourable weather conditions, and airports located in cold regions are equipped to face snow and ice storms. If the flight is cancelled by the company due to weather conditions, the European Regulation defines this as an "extraordinary circumstance." Although, these circumstances cancel the right to passenger compensation if they are not informed at least 15 days before departure and if the company does not propose a similar departure time (either with the original airline or another company).
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