Soaring Temperatures Reduce Departure Altitude

Aircraft departing in warmer weather do so at lower rates of climb than during periods of cooler weather. During heat waves, the air has lower density which increases the runway length aircraft need during take-off, and decreases lift and altitude gained as aircraft depart the airport.

The chart below shows average departure altitudes during the winter (January 19, 2022 through January 26, 2021 with a low of -16 °F) in blue and average departure altitudes from last summer (July 22, 2021 through July 29, 2021 with a high of 93 °F) in red. To compare aircraft departure altitudes, concentric rings near Minneapolis-St. Paul International Airport (MSP) runway were applied every mile between one mile and ten miles. Total average departure altitudes for flights at each ring are shown in the chart. 

Within three miles of MSP, during the two time periods used for comparison, aircraft were almost 400 feet lower in the hot period than during the winter. At nine and ten miles from MSP, aircraft altitudes averaged about 1,300 feet lower in summer compared to winter.

With the forecasted heat wave coming next week, communities may notice this change in departing aircraft but can rest assured aircraft are able to safely operate just as they do in cooler temperatures. These departure altitudes are normal and expected when temperatures soar.