Point of no return

Point beyond which turning back is no longer possible The point of no return (PNR or PONR) is the point beyond which one must continue on one's current course of action because turning back is no longer possible, being too dangerous, physically difficult, or prohibitively expensive to be undertaken. The point of no return can be a calculated point during a continuous action (such as in aviation). A particular irreversible action (such as setting off an explosion or signing a contract) can be a point of no return. Origins and spread of the expression The phrase "point of no return" originated as a technical term in air navigation to refer to the time and/or location during a flight at which the aircraft no longer has enough fuel to return to its originating airfield. Important decisions may need to be made prior to the point of no return, since it will be unsafe to turn around and fly back if the pilot changes their mind after that point. Otherwise, it may correspond to the aircraft's maximal safe range in a situation where the only possible landing site is the takeoff site, for example in the case of an aircraft to an aircraft carrier that is underway and distant from any airfield.