If contaminated runway data exists for the aircraft, should it be used to determine required runway for departure and landing?

Using contaminated runway data is essential for accurately determining the required runway lengths for both departure and landing. Contaminated runways, which may have conditions such as snow, ice, or water, can significantly affect an aircraft's performance. The presence of contaminants alters the available traction and can increase stopping distances, requiring adjustments to calculations for takeoff and landing requirements.

Incorporating contaminated runway data into performance calculations ensures that safety margins are maintained and that the aircraft operates within its required limits. This is particularly important because underestimating the required runway length can lead to dangerous situations during both takeoff and landing phases.

The other options suggest alternative considerations, such as not using contaminated data at all or only using it under certain conditions, which could compromise safety. It is critical to use accurate and complete data in performance calculations to guarantee the aircraft's safe operation in varying runway conditions.