Action Speed

Decision Speed

Critical Engine Failure Recognition Speed

Definition

V₁ is the maximum speed at which a rejected takeoff can be initiated in the event of an emergency. V₁ is also the minimum speed at which a pilot can continue takeoff following an engine failure.

Discussion

From the definition above, an engine failure that occurs prior to V₁ must result in a rejected takeoff. If the failure occurs after V₁, the takeoff must be continued. Transport category aircraft are certified, and their performance charts are developed, based on these criteria. However, the operational interpretation of V₁ has not always been in sync with the engineering definitions or certification standards.