AP: Heat could delay flights

The Associated Press reported on Aug. 5 that extreme heat can disrupt flights even when skies are clear, adding another source of summer delays beyond thunderstorms, snow or strong winds. On the hottest days, thinner air can make it harder for aircraft to take off safely, forcing airlines to remove passengers or cargo or carry less fuel, according to the AP report. A July 24 example in Las Vegas showed the issue in practice, when American Airlines offered compensation to travelers who gave up seats after temperatures reached 114 degrees Fahrenheit at Harry Reid International Airport. ### How does heat delay a flight if there is no storm? Hot air is less dense than cool air, and that changes the physics of takeoff. The Federal Aviation Administration says high density altitude reduces aircraft and engine performance, increases takeoff roll and decreases climb performance. The National Weather Service says high density altitude means the atmosphere reduces an aircraft’s performance capability below standard conditions. (usnews.com) Ross Aimer, a retired United Airlines captain and chief executive of Aero Consulting Experts, told the AP that hot air makes it harder for wings to generate lift and for jet engines to generate the thrust needed for takeoff. “There is a science behind all this,” Aimer said, according to the AP report. ### Why would passengers or bags get taken off a plane? (faa.gov) American Airlines said reducing a plane’s weight is a standard industry practice in hot-weather destinations when conditions require it to ensure a safe takeoff, according to the AP report. That can mean leaving behind passengers, cargo or fuel so the aircraft can depart within performance limits. (usnews.com) The FAA’s density-altitude guidance says that even at lower elevations, aircraft performance can become marginal and it may be necessary to reduce gross weight for safe operations. At higher-elevation airports, the agency says high temperatures can push conditions to the point that safe operations become impossible during parts of the day. ### Why did Las Vegas become the example? (usnews.com) Las Vegas illustrated the problem because Harry Reid International Airport combines desert heat with elevation. The AP said American Airlines offered compensation to customers who voluntarily gave up seats on a July 24 flight after temperatures reached 114 degrees Fahrenheit. Alan Price, a retired Delta Air Lines captain, told the AP that pilots and airlines calculate whether an aircraft can safely take off by weighing factors including aircraft weight, airport elevation and outside temperature before every departure. (faasafety.gov) Those calculations become more restrictive as temperatures rise. ### Is this only a desert-airport problem? (usnews.com) The AP said the issue is well known at airports in desert climates from the U.S. Southwest to the Middle East, but it can also affect airports with higher elevations or shorter runways even when temperatures are less extreme. FAA and National Weather Service guidance makes the same point in technical terms: hotter, thinner air reduces lift, thrust and climb performance, and longer takeoff rolls may be required. (usnews.com) The National Weather Service says temperature, pressure and humidity all affect air density, though heat is a central factor in high-density-altitude conditions. Its guidance says pilots mitigate the risk by reducing aircraft weight and favoring operations earlier or later in the day. ### What should travelers watch for on hot days? The National Weather Service and FAA both publish heat and density-altitude guidance that helps explain why a flight can be delayed without a visible storm. (usnews.com) For passengers, the practical signs are airline requests for volunteers, weight restrictions, longer ground delays and schedule changes during the hottest afternoon hours. As U.S. heat persists into August, travelers can check airline alerts, airport updates and federal weather guidance before afternoon departures. (weather.gov) The AP report was published Aug. 5, and the FAA’s density-altitude materials and the National Weather Service’s high-density-altitude page remain available for current reference. (usnews.com) (weather.gov)