Sept. 23, 2015

The FAA, which said last December that it wants pilots to make altitude corrections when approaching cold-temperature restricted airports, announced that those corrections are mandatory as of Sept. 17.

The new airport restrictions are the result of a risk analysis the FAA conducted in response to concerns over cold-weather altimetry errors, according to the agency. Since altimeters determine altitude by measuring atmospheric pressure, frigid temperatures can create inaccurate readings, which are especially problematic on approaches over mountainous terrain.

“Altitude corrections at cold-weather restricted airports will provide all users of these airports an improved level of safety during extremely cold temperatures,” said John Kernaghan, a pilot and member of NBAA’s Access Committee. “Pilots should familiarize themselves with the corrections required at these airports and plan their flights accordingly.”

The FAA compiled a list of hundreds of cold-temperature-restricted airports across the country that need altitude corrections to ensure the required obstacle clearance. When the temperature falls to an airport-specific threshold, pilots are required to correct for the cold temperature and report the corrected altitude to air traffic controllers.

A snowflake symbol, along with the temperature at which an altitude correction is required, will be added to all of the airport’s approach plates. The list of affected airports will be updated yearly.

Pilots who fly aircraft that can automatically compensate for temperature must ensure their system is working correctly for each segment of the approach – intermediate, final and/or missed approach – that requires an altitude correction.

This includes correcting the minimum descent altitude and decision altitude when the final approach segment requires compensation. Pilots without temperature compensation systems must use the Aeronautical Information Manual 7-2-3 ICAO Cold Temperature Error Table and manually apply the correction.

Review the FAA’s Information for Operators on the change. (PDF)