The FAA has released an updated list of airports where temperatures can fall so far in cold weather that altimeter error may require pilots on instrument approaches to make altitude adjustments to ensure safe obstacle or terrain clearance.
The updated list of cold temperature restricted airports is available in the Notice to Airmen Publication that takes effect Nov. 12, and includes examples of how pilots should make the necessary corrections—a procedure that became mandatory this year. The first list of affected airports was released in 2014.
AOPA has been active in the cold temperature restricted airports process through the association’s participation in the aeronautical charting forum. AOPA believes that the process is an important component of obstacle avoidance in the terminal environment at affected airports.
When the reported temperature at a listed airport drops to or below the published cold temperature restriction, aircraft on approaches may be flying lower than the altitude indicated on a barometric altimeter. Under those flight conditions, pilots “must make an altitude correction to the published, ‘at,’ ‘at or above’ and ‘at or below’ altitudes on all designated segment(s), for all published procedures and runways” for the airport, as shown alongside its entry on the list.
“Pilots may correct on the other segments of the same approach,” according to the Notices to Airmen publication. The publication’s discussion of the procedure specifies that they must advise air traffic control of the corrected altitude in use “if the additional corrections are in the intermediate and/or missed approach segment.”
Pilots should not change their altimeter settings to account for any needed altitude increases, the FAA said.
Instrument approach procedures for airports with a cold temperature restriction are published with a snowflake symbol.
Operators whose aircraft are equipped with avionics that compensate for temperature should ensure that the system is activate and working, “or else they should be using the chart and applying the manual adjustment,” said Rune Duke, AOPA director of government affairs for airspace and air traffic. Controllers are not responsible for assigning cold temperature adjusted altitudes.
Duke recommended that pilots become familiar with the altitude-adjustment process, and check the temperature of the destination airport during flight planning, when the adjustment should be computed.
“That is far easier and safer than trying to do it once airborne,” he said, noting that the Notices to Airmen publication provides a full explanation of the cold temperature restricted airport process, including examples of calculations.
The cold temperature error table used for calculations also may be found at the beginning of the Terminal Procedures Publication.
The FAA notified AOPA of two errors that appear in the edition of the notam publication in effect from Nov. 12 to Dec. 9. The correct temperature restriction at Freeman Field in Junction City, Kansas, is “-25C/-13F.” There is also erroneous information published about Alaska’s Teller Airport, where the intermediate segment is the only required segment for temperature adjustment. The errors will be corrected in the Dec. 10 edition of the notam publication.