One topic that sometimes receives scant attention during flight training is the effect of temperature on a pilot’s ability to understand just how much air separates them from the ground. Aircraft altimeters don’t operate normally when subjected to extremely cold temperatures. In cold regions of the globe, failure to compensate for extreme cold can induce significant errors in the indicated altitude, errors that can prove fatal during instrument flight.
In the U.S., the FAA publishes a list of airports where altimeter corrections must be considered when temperatures plummet and includes airports not just in Alaska, but some in California, Massachusetts, Minnesota, Idaho, Wisconsin and others.
Not only are pilots responsible for applying altitude corrections, but also for advising ATC when these corrections are made on any segment other than the final. ATC is not responsible for advising pilots that an altitude correction is required at a specific airport. Pilots flying internationally should also research how a particular country handles altimeter corrections when the temperature plummets in those areas.
The FAA recently announced the results of a risk analysis conducted to determine if any Part 97 instrument approach procedures pose a greater or reduced risk during cold temperature operations. The outcome led to the FAA to publish a Notice to Airman Publication (NTAP) providing pilots with a list of airports, the affected segments and procedures needed to correct published altitudes at the restricted temperatures. A number of previously listed airports have been removed.
