Spring! But FROST is still around!
March 1, 2018
How much can frost affect your plane? According to the NTSB:
• Frost the size of a grain of salt, distributed as sparsely as one per square centimeter over a wing's surface, can destroy enough lift to prevent your plane from taking off.
• Frost can reduce your wing's max lift by 30 percent or more.
• It can also reduce the margin of your wing's critical angle-of-attack by several degrees.
• Because frost disrupts airflow over your entire aircraft, it can increase drag by up to 40%.
The Federal Aviation Administration has updated their guidance on takeoff with polished frost in SAFO 06014. Here's an excerpt from the Safety Alert:
Discussion: Since 1960, operational experience and accident history have shown that contamination of any kind can adversely affect the aerodynamic properties of an airfoil, and that the safest course of action is to completely remove all contaminants from wing and flight control surfaces.
Therefore, the FAA cannot support the practice of merely polishing frost on a wing or control surface unless an aircraft manufacturer has developed explicit, approved procedures for doing so, and these procedures are strictly adhered to in operations and supported in training.
Recommended action: Pending rule changes, directors of operations, directors of training and pilots should ensure (1) that during operations in ground icing conditions no contaminants including frost are adhering to wings or to stabilizing or control surfaces immediately prior to takeoff; and (2) that "polishing frost" as a means to meet this objective is not practiced unless an aircraft manufacturer has developed explicit, approved procedures for doing so, and these procedures are strictly adhered to in operations and supported in training.
We at MnDOT Aeronautics are working "Toward Zero Deaths" in Minnesota aviation, and your continued safe practices in the air and on the ground are helping to make Minnesota one of the safest states in the U.S. Please use your checklists and continue to keep safety as your Priority One.
Remember, you as the PIC, are responsible for all facets of your flight preparation and flight. Your safety and the safety of your passengers is dependent upon your skills and best practices as a pilot.