Warming climate will force airlines to shed weight, increase costs

PHOENIX — More frequent sweltering summer days will force commercial aircraft to go on a diet, new research suggests.

At some airports, effects of future climate change could as much as triple the number of days when departing planes face weight restrictions, climate scientist Ethan Coffel said January 8 at the American Meteorological Society’s annual meeting.

Planes departing in warm, less dense air must reach higher speeds before generating enough lift to take off. If temperatures become too toasty, fully loaded planes can’t get up to speed before they run out of runway, and so have to lose weight. Since 1980, the number of summer days necessitating aircraft weight restrictions has increased alongside rising temperatures.

Coffel and Radley Horton of Columbia University projected the number of hot summer days under a worst-case greenhouse gas emission scenario for airports in Denver, New York City, Phoenix and Washington, D.C. For all four airports, the number of weight-restricted days increased 50 to 200 percent by midcentury. In Phoenix, they predict that the number of particularly hot days requiring a Boeing 737-800 to lose 4.5 metric tons before takeoff will go from near zero to 20 each year. For a long-duration flight, this amounts to a roughly 25 percent reduction in passenger and cargo weight.

Airports can counteract the problem by extending runways, Coffel said, but that is costly and not viable for urban airports with limited available land. Most likely, airlines will have to carry fewer passengers and less cargo per flight and raise prices to compensate, he said.

Editor’s note: This article was updated January 16, 2015, to correct that climate change could as much as triple (not double) the number of days that planes face weight restrictions, and that the number of weight-restricted days increased 50 to 200 (not 100) percent in the researchers’ projections.