Old Man Winter made an early appearance this year when snow and frost hit several locations in the North West. Many forecasts also warn of a tough winter ahead, with more snow and cold for much of the northern latitudes. With that in mind CTS has been hard at work at improving and expanding our current Anti-Ice Deice course with a new Winter Operations course. It's never too early to begin thinking about weather changes, and as summer draws to an end cold temperatures and winter storms will present unique challenges to pilots.
Altimeter Temperature Error Corrections
When considering temperature's effect on the accuracy of the altimeter the crucial value is the difference between the standard temperature and the temperature at altitude. This difference is what causes the error in indicated altitude. Put simply, when the air is colder than the standard temperature you are lower than your altimeter indicates. In terminal and mountainous terrain areas this can cause potential obstacle-clearance hazards. When operating in extreme cold temperatures you may want to compensate by adding a cold temperature correction using the ICAO Cold Temperature Error Table, accessed in the Aeronautical Information Manual, 7-2-3 (Table 7-2-3).
Aircraft Icing, on the Ground and in the Air
Icing is the other main hazard of cold weather operations. Whenever icing conditions exist aircraft operators must be careful not to takeoff with frost, ice, or snow adhering to the aircraft and pilots must conduct a pre-takeoff contamination check.
Aircraft icing and frost may occur anytime conditions are right, generally requiring an ambient temperature of freezing or below (32°F or 0°C) and the presence of liquid water (icing) or water vapor (frost). It's important to remember that for frost to form the aircraft surface must be below freezing, but the ambient air temperature may be above freezing since objects can be a different temperature than the surrounding air. Cold soaked fuel frost is also a concern. When cold soaking or light icing is suspected a tactile check of the aircraft should be performed - wet wings may actually be clear ice.
In-flight icing generally occurs in supercooled clouds and is greatest between temperatures of -20°C (-4 °F) and 0°C (32 °F), though runback icing commonly occurs in slightly warmer temperatures (between -5°C (23°F) and 2°C (35°F)). It is generally recommended to fly above the icing threat or to plan the flight to avoid areas where icing may be a threat or where there is significant frontal activity.
Winter Operations Course in Development
With these reminders noted, it may not be a bad time to take a refresher winter operations course. Airspace, High Altitude Weather, and International Operations aren't the only subjects to have received a recent face lift. We are also currently working on a new Winter Operations course to replace the current Anti-Ice De-ice subject. The new Winter Operations course will be available by the beginning of the new year and will include In-flight and Ground Icing Conditions; Anti-Icing/De-icing Fluids, Application Guidelines, and Holdover Tables; and Runway Contamination.
Interested? Let us know!
The Winter Operations course will be replacing the Anti-Ice/De-ice subject, so if you already have Anti-Ice/De-ice, Winter Operations will replace it when it is completed and available. Keep checking back here for the release date.
If you don't yet have a Winter Operations or Anti-Ice/De-Ice course, contact us today at 316-265-1585 for more information.