When is single engine taxi prohibited due to contaminants?

Single engine taxi is prohibited when ramps are contaminated with snow, slush, ice, or freezing precipitation because these conditions significantly reduce the ability of the aircraft to maintain control and can lead to accidents. Contaminated surfaces can cause a loss of traction, making it challenging for pilots to control the aircraft during taxiing. This requires a higher level of power, which could lead to an unsafe situation if the aircraft is unable to respond correctly to the pilot's inputs. Prohibiting single engine taxi during these conditions enhances safety by ensuring adequate power is available for control, minimizing the risk of skidding or accidents on the ground.

In contrast, dry taxiways do not present the same risks as contaminated ramps, allowing for single engine taxi to be conducted safely. Heavy rain conditions may require specific precautions, but they are not universally prohibitive for single engine taxiing. Low visibility impacts flight operations more than taxi procedures and does not inherently restrict single engine taxi operations. Therefore, prohibiting this practice in cases of ramp contamination is a critical safety measure.