Extreme temperatures in parts of the US and around the world are forcing airlines to reduce fuel loads, shed passengers or baggage, or wait for daytime temperatures to drop in the evenings, to fly some aircraft.
High temperatures reduce the performance of engines and the lift airplanes wings are able to produce, which is leading Las Vegas-based Allegiant Airlines to warn that it will delay flights if there’s a threat to passenger safety.
Earlier this month, several Delta passengers voluntarily got off a flight from Las Vegas to Atlanta after aircraft weight issues in the heat caused delays, Bloomberg reported.
“Additional protocols have been put in place to address the operational impacts extreme heat has on aircraft, including loading less fuel to account for weight and balance and schedule refuelling along the route when needed,” Delta said in a statement.
Last week, a Delta flight from Las Vegas to Atlanta sat on the tarmac for four hours in 46 degrees heat, without air conditioning, causing some passengers to experience heat-related sickness. The US transportation secretary, Pete Buttigieg, called the incident “shocking”.
[ ‘Hell on earth’: Phoenix’s extreme heatwave sparks calls for actionOpens in new window ]
The US department of transportation confirmed it is investigating Delta the circumstances. Multiple passengers were seen by medical first responders and two people went to a local hospital. Delta says it has offered compensation and apologised to affected passengers.
American Airlines has also responded to the issue, saying it is taking extra steps to make sure it has cooled air on jet bridges hooked to planes and to perform early maintenance on auxiliary power units, the smaller engines that give power when larger engines are shut down.
“Though we’ve had a very small number of diversions and delays related to high temperatures, the plan we have in place has allowed us to avoid significant impact,” an American Airlines spokeswoman told Bloomberg.
The complications that high temperatures can cause a plane’s performance is due in part to some flight manuals in some aircraft do not go above 49 degrees. “When exposed to extreme heat exceeding its maximum operating temperature, passengers aboard the airplane could be at risk,” according to Monroe Aerospace.
Last week, park service officials in Death Valley, where temperatures can reach 54 degrees, warned hikers that rescue helicopters would not be able to fly to their aid during daytime.
[ European heatwaves Q&A: How deadly are they and how hot will they get?Opens in new window ]
A heat dome over the US southwest had caused temperatures in Las Vegas to soar to 47 degrees on July 16th and Phoenix to hit 48 degrees. Extreme temperatures in Phoenix in 2017 also forced the cancellation of some 60 flights, primarily by smaller regional jets and older aircraft, over the course of three days because safety calculations were not calibrated for temperatures above 49 degrees.
Industry expert Robert Mann previously told the Guardian that flights “have to wait until the sun goes down, the temperature drops, and they can take off”.
He added: “As temperatures increase, there are going to be more occasions, at more places, where certain flights are going to have to take payload limitations or stop en route because they had to short-load the fuel.” – Guardian