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Why does the weather affect flights?

The weather forecast is a key element of the pilot's pre-flight checks and flight crew will continually update their weather information throughout a flight.

There are lots of types of weather to consider. Why does fog affect flights? How can snow cause problems on runways? And will high winds have an impact on my flight?

Why are flight delays more likely in winter?

Fog, snow, ice and cross winds mean that air traffic controllers have to increase the gap between planes that are landing, reducing the number of aircraft that an airport can manage. The same weather can make it slower and more difficult for the planes to taxi between runway and terminal building. As many commercial flights are cruising more than five miles above the ground, they can be affected by different weather than we are experiencing on the ground.

Safety is always the first consideration for the aviation industry. An aircraft that's stood overnight in freezing weather will need de-icing before its first flight in the morning. That's a fairly big task for one plane but imagine the task at Heathrow on a snowy January morning. At the same time there are miles of taxiways and runways to clear. Then think about the people who do this work getting to the airport - the same snow and ice are probably affecting the roads and railways. 

What should you do before travelling?

If you are travelling by air in winter, check the weather forecast the night before and plan accordingly. In poor weather allow extra time to get to the airport and have a contingency in mind in case of a weather delay.

Check with your airline if you think a delay is possible. On most occasions the advice will be to arrive at the airport as normal but sometimes that will change.

When very severe weather is expected, airports and airlines may work together to implement planned cancellations to some flights. This helps to minimise the delays to remaining flights and, although it may be later than expected, it helps most passengers get to their destination as quickly as possible.

There is a lot more advice about air travel for passengers on the Civil Aviation Authority website including information on your rights as a passenger when there are severe delays.