An approaching heat wave is set to make life uncomfortable for people in the eastern United States and could make air travel difficult.
High temperatures can force planes to reduce their loads, leading to delays and passengers being removed from flights, and hot days can also make the cabins of planes parked on the tarmac before takeoff or after landing sweltering hot.
The impact of extreme heat on aircraft
Planes absorb energy from the sun and the ground, and passengers on board also increase heat and humidity.
Hot air is thinner and less dense than cold air, experts at Embry-Riddle Aeronautical University explain in a post on the school's website. As a result, planes need less thrust when taking off and need more speed to get airborne, which means they need more space on the runway to reach that speed.
“The only way to enable takeoff on shorter runways is to reduce the weight of the aircraft,” Bob Thomas, assistant professor of aeronautical sciences at Embry-Riddle University, said in the post.
On days when weight restrictions are in effect, airlines typically cut back on fuel, baggage and passengers. A Columbia University study that looked at four high-risk airports — Denver, New York's LaGuardia, Phoenix and Reagan National near Washington — found that the number of days when weight restrictions are in effect is expected to double.
Flights may be delayed or canceled altogether until temperatures cool. If flying on a hot day, passengers can have a miserable experience if they get stuck on the tarmac. During last summer's heatwave, passengers on several airlines complained of being stuck on planes that were too hot. In at least one case, a passenger required medical attention.
How to (and how not to) cool down an airplane
Federal regulations say travelers have the right to a “comfortable cabin temperature” during tarmac delays, though the regulations don't define “comfortable.” The FAA reauthorization bill signed into law last month includes a mandate to study and evaluate cabin temperature standards.
An airplane's cooling system works best when the plane is flying, not when it's on the ground. When the plane is on the runway, the captain may shut down the main engines, which are best suited to power the air conditioning. In those cases, the auxiliary power units may not be able to cool the plane as much as needed.
Airlines often pump cool air into the cabin before boarding, but on very hot days, this may not be enough to make the cabin comfortable.
“At some point on the temperature scale, even the best equipment has a limit,” Billy Nolen, a former acting FAA administrator and chief safety officer for aircraft manufacturer Archer, told The Washington Post last year.
Airlines say they are taking steps to keep planes cool enough, but acknowledge that such measures are needed more frequently.
“We take this issue seriously and must continue to do so,” American Airlines Chief Executive Robert Isom said in a conference call with investors last summer.
Experts recommend that air travelers avoid booking flights during the hottest times of the day, with early morning and late evening flights offering the lowest chance of suffering from heatstroke, according to a post from Embry-Riddle.
Many in the aviation industry are already recommending booking the first flight of the day to avoid weather-related delays, which tend to increase throughout the day.
“Nobody wants to be on a plane at 5 a.m., but the temperatures are cooler that time and the plane is likely to leave on time,” Brian Dills, a lecturer in the University of North Dakota School of Aeronautics, told The Washington Post last year.
Andrea Sachs contributed to this report.
