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Airplanes Don’t Like Extreme Heat: Tips for Avoiding Flight Delays in Summer’s Hot Weather

Summer flying can be tough. Especially this year. Plane engines simply behave differently in the summer, and smart travelers use that information to avoid delays and cancellations.

Flying in the summer always presents challenges. But flying this summer promises to be particularly challenging. 

Airlines are already dealing with tremendous stress, including pent-up demand and delivery delays on new aircraft. 

Now, we have to add record-setting heat waves.

The effect on hot weather on airlines is much more significant than most passengers know. Here’s what to expect, what to know, and how avoid flight delays and cancellations.

Summer heat affects aircraft

The fact is jet engines simply don’t like heat.

Hot weather produces lower air density, which means those powerful engines sometimes cannot suck in sufficient air for combustion and propulsion. Thinner air density can have negative effects on performance, efficiency, and fuel consumption. In the heat, airplane engines may require more takeoff distance to counteract the thinner air.

Longtime airline colleagues assure me that jet engine technology has greatly improved in recent years, so some hot weather problems of the past have dissipated. But not entirely. What does this mean for passengers? Plenty.

I haven’t used my FAA aircraft dispatcher license in many years, but I vividly recall being faced with tough decisions on very hot days to mitigate diminished takeoff performance resulting from extreme heat.

• bump passengers to reduce takeoff weight

• bump baggage to reduce takeoff weight

• delay the flight until temperatures drop

• schedule a fuel stop en route (which delays arrival and potentially creates a cascade effect of missed connections)

• cancel the flight outright

Obviously, none of these options are good for passengers. But safety comes first, and unfortunately, sometimes the only safe choices are less than ideal. 

Like in June a few summers ago, when temperatures in Phoenix reached 118 degrees Fahrenheit (47.8 Celsius), forcing dozens of flight cancellations.

In certain seasons, I try to select optimal hubs when making connections on major airlines. 

For example, in the winter, I like to avoid Chicago, Minneapolis, and Denver. And when temps hit three digits in July and August, I try to avoid Sun Belt locations like Atlanta (Delta’s hub), Miami (American), Dallas (American, Southwest), Houston (United), and Phoenix (American). 

But there’s an obstacle to this tactic. Due to extreme industry consolidation, we now have fewer hub choices than before, so you might not be able to avoid cities where weather is more likely to pose a problem.

And high temperatures are even worse when combined with two other factors: short runways and high altitudes. Dispatchers and pilots often request runway changes. Unfortunately some of the nation’s busiest airports can’t physically accommodate such requests. 

The longest runway at New York/JFK is 14,511 feet. But other high-volume airfields don’t have as much room: Washington/DCA’s longest runway is 7,169 feet, New York/LaGuardia’s is 7,003 feet, Burbank’s is 6,886 feet, and Chicago/Midway has just 6,522 feet. When extreme heat strikes, those may be too short for some full flights (and this summer, most flights are full). 

Also, without geeking out too much on physics, another key factor in engine takeoff performance is altitude, because air pressure and density decrease at higher elevations and aircraft need more runway to get up to speed. So mitigation decisions at high-altitude airports are often even more acute than at airfields closer to sea level.

(Photo credit: MNBB Studio / Shutterstock)

How to plan to fly in extreme heat

Some advice is evergreen during busy periods like summertime. You already know that you need to get to the airport early. You probably also already try to avoid checking bags. 

But here is more to ponder.

Take nonstops when possible. 

I fully understand that much of the country is dependent on the airlines’ hub-and-spoke systems, because after the airlines consolidated and competition fell, many American communities are served by fewer nonstop flights

But if possible and if affordable, this summer is the time to consider flying nonstop, even if it costs a little more, to avoid hassles. 

It really comes down to simple math: Do you want to double your odds of experiencing flight delays or cancellations? If you’re a family of four, do you really want to risk 16 potential bumpings by taking two flights each way, rather than just risking 8 by taking nonstops? 

Heatwaves are not the ideal time to roll the dice on such risks. 

Choose airports wisely. 

I know—I already gave you a lot to contemplate on airport climates, altitudes, and runway lengths. 

But also factor congestion. In dozens of cities and regions around the country, you’ll have a choice of multiple departure airports depending on what you consider a reasonable drive to an alternate secondary facility. (For example, I have friends in Illinois who drive several hours to Milwaukee to avoid the grief of Chicago.) 

Know the best days and hours to fly. 

Which days of the week are usually less busy? Experts suggest Tuesdays and Wednesdays, but the list of caveats is lengthy, and it can vary by airport, month, etc.

The best time to fly is easier to pin down. You may not like an alarm clock ringing while it’s still dark outside, but the simple fact is the first flights of the day have the greatest chance of not being delayed or canceled. And this can be especially true when summer thunderstorms roll in during afternoon and evening hours.

To illustrate, Department of Transportation statistics for July 2023 proved the best hour of the day to depart on time from the nation’s 30 busiest airports was 6–7 am (86.2% on time), and the worst hour was 8–9 pm (49.6% on time). It’s been this way forever.

Fly the most reliable airlines. 

Monthly DOT reports also rank U.S. airlines by on-time performance. The most recent data, for the first quarter of 2024, exposes how the ten largest domestic carriers stacked up for on-time arrivals (punctuality for some airlines might be different during summer).

Delta is currently the most on-time airline, with 83.61% departing in a timely manner. That airline is followed by Hawaiian (79.68%), United (79.10%), Southwest (77.67%), Allegiant (77.64%), American (77.26%), Alaska (74.34%), Spirit (73.13%), Frontier (72.03%), and in 10th place, JetBlue (70.61% ).

Be alert to your airline’s policies. 

Yes, I’ve recently shared good news lately on Frommer’s from both Congress and the DOT on new passenger protections. However, most rules won’t kick in until after the summer of 2024. 

In the meantime, check out the DOT’s Airline Cancellation and Delay Dashboard, which links policies on service and amenities during flight disruptions for the largest domestic carriers.

You should also visit your carrier’s website and pull up its Contract of Carriage (COC), which provides details on what it will—and will not—do for you. Just because it’s written in the COC doesn’t mean airlines will automatically fulfill their promises, so be prepared to fight for your rights.

Consider travel insurance and booking with travel advisors.

Travel insurance may make sense for some trips, but there are caveats. Frommer’s developed a guide to address this.

You also may want to rely on travel advisors (we used to call them travel agents), since many of them offer 24/7 assistance during airline meltdowns. The American Society of Travel Advisors compiles a detailed directory

File complaints. 

If things do go wrong—which will be inevitable for some this summer—keep detailed records and promptly file claims at this link. The DOT has info on filing complaints against airlines.

Stay cool!

William J. McGee is the Senior Fellow for Aviation & Travel at American Economic Liberties Project. An FAA-licensed aircraft dispatcher, he spent seven years in airline flight operations management and was Editor-in-Chief of Consumer Reports Travel Letter. He is the author of Attention All Passengers and teaches at Vaughn College of Aeronautics. There is more at