Criteria for Flight Delays During Snow
Snow delays occur when the Federal Aviation Administration, the local airport or a pilot decide that the weather conditions are too dangerous for safe travel. The problematic weather may occur at the departure or arrival airport, or en route. A delay may also occur even when your airport has perfect weather. Each commercial airplane makes several trips a day and a previous flight that the plane was scheduled to undertake may have been cancelled or delayed by weather. The Federal Aviation Administration requires every airport that receives more than 6 inches of snow a year to create a snow and ice control plan and a committee to create guidelines for winter operations.
Airline Snow Delays
Snow can cause issues during take-off, landings or even while in flight. The FAA considers a runway to be contaminated when standing water, snow, ice or slush are present. Standing water, snow or slush can make it difficult for a plane to take off or land safely as they can cause friction, reducing traction which can lead to hydroplaning/aquaplaning. Landing distances required are different for wet and dry runways, meaning some planes may not be able to land safely on their usual runway when snow is present. Small snowstorms without much accumulation aren't usually a concern at airports that are prepared for snow as they have the needed snow-removal equipment on hand. Large amounts of snowfall, however, make it difficult to keep runways clear. An airport that doesn't typically remove any snow may be unprepared to handle even a small amount of snow. Blizzards and thundersnow storms can cause visibility, icing or turbulence problems during flights and landings.
High Wind Delays at Airports
Strong winds can cause visibility issues for pilots even when snow is not falling. While the FAA determines safe parameters for crosswinds during flights, primarily for landings and takeoff, a local airport may need to cancel flights due to blowing or drifting snow. A strong wind might be OK for landings or departures on a sunny day, but when combined with ice may cause problems. Winds from winter storms can be strong and can lead to what meteorologists call "bomb cyclones" or "bombs." This type of wind can prevent take-offs and landings, or cause extreme turbulence in the air, leading to flight delays.
While planes can be de-iced if still at the airport, icing is an extremely dangerous weather condition for flying, landing and take-offs. The runways become slick, making safe landings unlikely. Additionally, ice build-up on the aircraft itself can lead to mechanical or functional problems. In-flight icing is a bigger problem for small aircraft, but it can still cause issues on large planes. If freezing rain is occurring, it is likely that flights will be delayed or canceled as ice can build up on the wings, windshields and runways.
Airline Obligations in Bad Weather
A "contract of carriage" or "conditions of carriage" forms a written agreement between an airline and its passengers. These contracts state that airlines are not responsible for providing compensation to passengers when the event affecting a delay in flight is related to weather or another incident outside of the airline's control. Passengers will be rerouted on the next available flight to their original destination or to another nearby destination of their choosing at no cost. Passengers are also eligible for a refund on the unused portion of their ticket; this is usually made as a travel certificate for a future flight. Passengers are typically not eligible for hotel compensation in the event that their flight is delayed a full day or more when the delay is weather-related. Airlines often allow passengers to change their travel plans for free ahead of time when a winter storm is pending. This can help reduce chaos at the airport when flights are cancelled.