By Erin Delmore
When you think of airplane delays, the common culprits come to mind: snow, sleet, storms. Add one to the list: heat waves. They’re in full swing and they’re grounding air travelers.
“A lot of the time in the summertime you’ll see airplanes having to be offloaded, passengers or they have to offload bags and that’s primarily due to the fact that the airplane’s overweight, or the plane can’t take off given the environmental circumstances outside and they have to offload bags and passengers,” said President and CEO of Infinity Flight Group Gregory John.
A Phoenix-bound plane had to turn back around in June when air temperatures reached a record-breaking 117 degrees Fahrenheit. It’s one of several flights this summer deemed too hot to handle.
When planes have trouble flying in extreme heat, it has less to do with the mechanics of the aircraft and more to do with the atmosphere.
“In the wintertime, the air is very dense. The air molecules are very tight together, so performance is better. The more air molecules you have underneath the wing and above the wing, you get better performance. The airplane climbs better,” said John. “In the summertime those same air molecules are further apart,”
That inefficiency means it takes longer to takeoff and land, necessitating longer runways. Some airports, like Trenton-Mercer, just don’t have them.
“You have to look at what’s happening on the ground as well. When it gets very very hot it’s not safe for people to be out on the tarmac, which retains the heat, and so people suffer heat exhaustion. It’s just not safe for them to operate — the baggage handlers, the ramp folks. In addition, when it gets really hot the asphalt will start to lose its rigidity. It’ll get soft, and so when you have these tremendous weights of these airplanes on it you can’t really operate in those conditions. So it’s a very complex problem,” said Georgia Tech Aerospace Engineering Professor, Marilyn J. Smith.
Extreme heat can cause thunderstorms. They block routes and cause airplanes to make detours to travel further to get to their destinations. That’s one common cause for delays. Plus, a longer trip takes more fuel, but fuel expands in warm weather so less of it fits into the gas tank.
“You might not be able to make it quite as far or plan for those alternates. It’s an issue on longer-haul flights that’s where it really becomes an issue. Going cross country, going across the Atlantic or into South America,” said John.
Airlines compensate by offloading passengers and their baggage, and in extreme cases they cancel flights. That can leave travelers stranded during the busiest travel months of the year. The good news: once the plane reaches cruise altitude, the effects of air temperature have little impact on the flight itself. So like all travel, getting there is half the battle.