What weather phenomena can rapidly challenge a de-iced aircraft before takeoff?

Sudden snowfall or freezing rain just before taxiing represents a critical challenge for a de-iced aircraft as it can quickly accumulate ice or snow on the aircraft's surfaces, compromising its aerodynamic performance and safety features. Even if the aircraft has been de-iced prior to this sudden change in weather, the newly formed ice or snow can necessitate a re-evaluation of its readiness for takeoff. This phenomenon highlights the importance of being vigilant about changing weather conditions during the pre-flight phase, as these conditions can unexpectedly affect an aircraft’s ability to take off safely.

Other options, such as clear skies and warm temperatures or gradual temperature changes, generally do not present immediate de-icing challenges since they are more stable conditions that are less likely to lead to ice formation. Light rain and cloudy conditions may also not create the same urgent need for de-icing as immediate snowfall or freezing rain would, as the impact on the aircraft surfaces may not happen quickly enough to create safety concerns before takeoff.