Why must de-icing procedures be completed before taxiing?

De-icing procedures must be completed before taxiing primarily to ensure that aircraft surfaces, including wings, tail, and control surfaces, are completely clear of ice or snow. Ice or snow on these surfaces can significantly alter the aerodynamic properties of the aircraft, leading to a loss of lift, increased drag, and potentially hazardous flight conditions. Ensuring that these surfaces are free from contaminants allows the aircraft to perform optimally during takeoff and throughout the flight.

While saving time during the pre-flight checklist, compliance with safety regulations, and the appearance of the aircraft may be considerations in the broader context of operations, they do not directly address the critical reason behind the timing of de-icing procedures in relation to safe and effective flight operations. The priority is always focused on ensuring that the aircraft is in a condition that allows for safe maneuvering and operation, particularly during takeoff when the risks are highest.