At what speed is an engine failure considered a critical issue during takeoff?

An engine failure during takeoff is considered a critical issue when it occurs between 80 knots and V1. This phase of flight is crucial because it represents a point where the aircraft is committing to takeoff. At speeds below 80 knots, the aircraft is still typically in a configuration where an abort is manageable and recovery options are available.

Once the speed exceeds V1, the aircraft has reached the minimum speed dictated for safe takeoff; at this point, parameters are such that stopping the aircraft on the remaining runway would present significant risk and challenges. Hence, if an engine failure occurs after V1, the pilot must continue the takeoff. The interval between 80 knots and V1 is critical because the pilot is close to a decision point, where they need to determine if they can safely proceed with takeoff or abort depending on performance considerations and aircraft control.

This understanding is vital for ensuring safe operations during takeoff and highlights the importance of training in engine-out scenarios at defined speed intervals.