FAA Aircraft Dispatcher (ADX)Regulations (Part 121)Medium
A Part 121 dispatcher is reviewing ground icing conditions before releasing a flight. Under 14 CFR 121.629(c), an aircraft may not take off when frost, ice, or snow is adhering to which surfaces?
- AWings, control surfaces, propellers, engine inlets, and other critical surfaces
- BOnly the leading edge of the horizontal stabilizer
- CAny exterior surface except the wings
- DOnly the fuselage and cargo doors
Show answer & explanationAnswer & explanation
Correct answer: A. Wings, control surfaces, propellers, engine inlets, and other critical surfaces
14 CFR 121.629(c) prohibits takeoff when frost, ice, or snow is adhering to the wings, control surfaces, propellers, engine inlets, or other critical surfaces of the aircraft. This 'clean aircraft concept' ensures aerodynamic performance is not degraded by contamination.
Why the other options are wrong
- B. The rule covers more than just the horizontal stabilizer leading edge.
- C. Wings are explicitly included, making this option incorrect.
- D. Fuselage and cargo doors are not the critical aerodynamic surfaces addressed by this rule.
Clean Aircraft Concept (121.629)
Prohibition on takeoff with frost, ice, or snow adhering to critical aerodynamic and engine surfaces.
- Applies to wings, control surfaces, propellers, engine inlets
- Requires ground deicing/anti-icing when contamination present
- Holdover time tables used to determine deicing effectiveness
Memory trick: Clean wings, clean tail, clean engines — or you don't fly.