Airlines at Phoenix Airport, Arizona were forced to cancel around 40 flights yesterday due to extreme temperatures.
The excessive heat (49 C !!! ) is currently higher than the operating temperature of some aircraft.
American Airlines was forced to cancel a dozen of flights.
Most of the cancelled flights were operated with Bombardier CRJ aircraft, which has a maximum operating temperature of 48 C.
A very nice article on “hot and high” on wikipedia.
In aviation, hot and high is a condition of low air density due to high ambient temperature and high airport elevation. Air density decreases with increasing temperature and altitude. At any given true airspeed, lower air density reduces the amount of lift generated by the wings or the rotors of an aircraft, which may hamper an aircraft’s performance and hence its ability to operate safely. The reduced density also reduces the performance of the aircraft’s engine, compounding the effect. Aviators gauge air density by calculating the density altitude.
“Hot” and “high” do not have to be mutually inclusive of one another, though this tends to be the exception. If an airport is especially hot or high, the other condition need not be present. Temperatures can change from one hour to the next, while the elevation of an airport always remains constant. The fact that temperatures decrease at higher elevations mitigates the “hot and high” effect to a certain extent.