During takeoff, how does high humidity impact performance?

High humidity negatively affects aircraft performance during takeoff due to the change in air density. When the humidity is high, the air contains a greater proportion of water vapor, which is less dense than the nitrogen and oxygen that make up dry air. This lower density means that each cubic foot of air contains fewer air molecules, resulting in reduced lift generated by the wings and decreased engine performance because the engines rely on oxygen intake to produce thrust.

As a consequence, aircraft require a longer takeoff distance to achieve the necessary speed for lift-off in humid conditions. This is particularly critical in situations where runways are short or if the aircraft is already at a higher weight for a given flight. Thus, high humidity conditions hurt overall performance during takeoff phases, making it essential for pilots to take these factors into account during pre-flight planning and operations.