As Boston prepares for its first winter storm, I thought I would do some research over the holiday weekend on the impact to flights and decisions made based on conditions. I was thinking that there must be some standards to when a decision is made to delay flights due to weather…especially snow storms. My quest was to find out what, and who, determines a delay or cancelation to flights. Let’s take a look at what I found out.
First of all, 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.
Below is what I found out regarding who decides the impact to flight schedules. It’s interesting to see the different decision makers for each of the types of conditions. Winter weather is broken down into three considerations; accumulation, winds, and ice. There are different impacts to flights for each.
SNOW – 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. Capability of removing snow directly impacts decisions as well as visibility, icing or turbulence problems during flights and landings. The airport determines the conditions of the runway when deciding on flight delays.
WIND – 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.
ICE – 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. The pilot often determines the potential impact to the plane and can request a delay based on these conditions.
Many of us are getting ready for several months of winter havoc impacting our travel. Being aware of conditions at your airports and flight patterns may help you make better decisions in advance before heading out. Be prepared, dealing with delays is just a part of our job.
Have a favorite snow delay story? Share your comments below.