An American Eagle CRJ900

American Airlines

American Airlines has canceled 20 regional flights scheduled for Tuesday at Phoenix Sky Harbor International Airport because of excessive heat that could affect aircraft performance.

That could affect some Tucsonans planning to fly from Phoenix, but there have been no heat-related flight cancellations at Tucson International Airport and none are expected.

Over the weekend, American sent notices to passengers booked on Phoenix flights from Monday through Wednesday, warning them it may have to ground flights in Phoenix during a heat wave that could send the temperature soaring to 120 degrees.

American is allowing Phoenix passengers flying during the peak heat period between 3 p.m. and 6 p.m. to change flights without a fee. The forecast calls for a high of 118 on Monday and 120 on Tuesday in Phoenix.

The affected Tuesday flights are American Eagle routes operated by Mesa Airlines and SkyWest Airlines, which fly Bombardier regional CJR airliners that are most affected by excessive heat.

American had not canceled any Monday flights to or from Sky Harbor as of noon, an American spokeswoman confirmed, adding that Tuesday’s canceled flights include both departures and arrivals.

The Tucson airport has no record of heat-related flight cancellations and has heard nothing regarding any possible cancellations of Tucson flights during the current heat wave, TIA spokesman David Hatfield said, noting that individual airlines make those decisions.

Extreme heat creates changes in the air density that make it harder for airplanes to take off. Airlines respond by imposing weight restrictions, such as carrying less cargo and fuel, in some cases, they will ground flights during peak heat.

According to American, the maximum outside operating temperature is 118 degrees for the Bombardier CJRs, while it’s 127 degrees for Airbus airliners and 126 degrees for Boeing aircraft.

The excessive-heat window potentially affects 15 departures and 17 arrivals on American Eagle daily at Sky Harbor, American said.

American Eagle averages about 90 departures and 90 arrivals daily at Sky Harbor, the airline said.

American passengers can their flights by contacting reservations at 1-800-433-7300.