Triple-digit temperatures are expected to cause flight delays this week.
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IIt definitely gets warm there. The Northeast and Midwest are in a heat wave, with sky-high temperatures and humidity all week, according to the National Weather Service, which warned that the looming heat dome “could see temperatures above the century mark.”
This will make for an unpleasant flying experience for many air travelers, for various reasons. First, extremely high temperatures can force airlines to reduce aircraft weight, which in turn can lead to flight delays and passenger crashes.
As of 1 p.m. Eastern time on Monday, more than 2,500 flights within the U.S. had been delayed — a huge increase from the approximately 1,400 delays reported as of 10 a.m., according to FlightAware, a free app that provides real-time, historical and predictive flight tracking data. Expect the number of delayed flights to rise as the day progresses, perhaps exceeding last Friday’s total of more than 8,300 delayed flights.
“High temperatures reduce air density, which means the aircraft can produce less power or thrust,” explains Dr. Bob Thomas, assistant professor of aeronautical sciences at Embry-Riddle Aeronautical University in Daytona Beach, Florida. “When it’s that hot and you’re creating less thrust, you essentially have to reduce the weight of the aircraft to be able to use the available runway and also to meet the climb restrictions set by the FAA.”
But Dr. Thomas says there is no magic temperature that universally triggers the decision to reduce the number of passengers on a flight. “It’s literally an airport-to-airport thing, and even a runway-to-runway thing, because different airports and different runway lengths are all different. In the mountain areas they are higher, which makes it worse,” he said, adding that in an area like Phoenix it can get so hot that airlines have no choice but to cancel flights. “Essentially the runways are becoming too short.”
According to asphalt rules Introduced by the Department of Transportation (DOT), airlines are required to deplane passengers after three hours for domestic flights and after four hours for international flights. But extremely hot days can lead to passengers sitting in sweltering cabins for hours as the plane is stuck on the tarmac, waiting for takeoff or after landing.
The worst-case scenarios make headlines. Last July, a United Airlines flight was delayed for seven hours on the Newark airport tarmac, leaving passengers stranded without food, water or air conditioning, according to local news reports. The same month, a Delta flight was held on the tarmac in Las Vegas for four hours on a day when temperatures peaked at 111 degrees, reportedly without air conditioning. The heat inside the plane was so intense that several passengers vomited and fainted, and two people ended up in hospital, Reuters reported.
Essentially, an aircraft’s cooling system only works when it is in the air. When the plane flies at 35,000 feet and draws in air at a temperature below freezing, the cabin crew can adjust the temperature in the cabin to their liking.
“The air conditioners on airplanes work differently than you might expect,” says Dr. Thomas. “Normally you have an air conditioner and a big hose that pumps cool air into the plane while you’re at the gate. So once you break away from that and you’re sitting on the ground with no air flowing through the plane, there’s essentially no way to cool the air before it’s brought into the cabin.
Tips for summer flying
A weather problem in one region can become a national air travel problem as airlines reuse aircraft and crews for multiple trips throughout the day, creating a domino effect. For example, a late morning flight delay in Boston could prevent a plane from flying to Dallas for an early afternoon departure, which in turn could hold up the same plane’s late afternoon flight from Chicago.
The easiest way for travelers to reduce the risk of flight disruption is to book an early flight, when temperatures are cooler. “Especially in the Southeast or anywhere south where there are afternoon thunderstorms every day, it’s always smarter to take the very first flight in the morning,” says Dr. Thomas. “You avoid the risk of thunderstorms slowing down and changing routes and things like that.”
FlightAware can tell you whether your aircraft is on schedule or warn you in time that there may be a problem. Enter your flight details and then click the ‘Where is my plane now?’ link just below the flight number. If your aircraft is behind schedule, you can take action accordingly. FlightAware also allows you to sign up for alerts sent via email or text message if there are any changes related to your flight. You can search by flight number or city link.