When do you need both wings and cowls for takeoff?

The requirement for using both wings and cowls for takeoff is crucial under specific conditions related to temperature and potential contamination. When the outside air temperature (OAT) is 5°C or below and there is ground contamination, this indicates a higher risk for ice formation on the wings and critical engine surfaces.

In this situation, pilots are instructed to ensure that both the wings and cowls are heated adequately to prevent any icing that could adversely affect aircraft performance during takeoff. Ice on the wings can disrupt airflow, leading to decreased lift and increased drag, while ice in the engine inlets can lead to engine performance issues or failure.

The guidelines emphasize that when temperatures drop to this level, along with the presence of contaminants such as ice, snow, or slush, it is essential to apply both wing and cowl heating before takeoff to ensure safety and adherence to operational standards.

Other scenarios offered, such as temperatures above 10°C or when no moisture is present, typically do not require the same level of precaution since the risk of ice formation is significantly lower.