An updated list of U.S. airports where operations could be limited by the effect of extremely cold temperatures on aircraft altimetry is now available from the FAA. A number of airports have also been dropped from this new version, InFO 15002. The agency reminds pilots that they, not ATC, are responsible for including temperature-based altitude corrections into their approach planning. However, advising ATC of planned altitude corrections in the final segment is not required.
The new document follows an extensive agency risk analysis of precisely which instrument approach procedures (IAP) can be affected during winter weather. The agency also reminds pilots that temperatures for cold temperature-restricted airports are separate from the temperatures published on area navigation (Rnav) approaches. Temperature restrictions on Rnav approaches for lateral navigation (Lnav)/vertical navigation (Vnav) minimums must be followed, even if they are warmer than the temperature associated with the “snowflake” icon on the associated IAP.
The study was guided by using the coldest recorded temperature for an airport in the last five years and specifically investigated if there was a probability that expected barometric altimetry system errors could exceed the required obstacle clearance used on procedure segment altitudes.