- the point in a flight at which an aircraft will lack sufficient fuel to return to its starting point.
- the critical point in an undertaking, decision-making process, etc., where one has committed oneself irrevocably to a course of action or policy.
- a point at which an irreversible commitment must be made to an action, progression, etc
- a point in a journey at which, if one continues, supplies will be insufficient for a return to the starting place
