The graph shows flight envelope for a F104 without external stores.
The horisontal axis shows speed in mach numbers,
the vertical axis altitude. Det filled part shows altitude/speed combinations that can be maintained in military power, that is without lighting the afterburner.This field is limited in speed to mach 1.0 and in altitude to slightly above 40.000 feet.
By lighting the afterburner the operational area grows in addtion with the hachured field. This is limited at low altitudes by maximum equivalent airspeed (750 K) and CIT 120 degrees due to compressive heating of the air entering the compressor. The upper limit of this field depicts how high the plane can climb. The drop in altitude around mach 1.0 is due to the increased drag during sonic transition. Maximum altitude with afterburner varies between 50.000 feet and 55.000 feet.
It is possible to get higher by trading speed for altitude, or zooming as it is known. The zoom limit shows how much altitude can be obtained from a given speed reduction. What altitude can be reached depends on which maneuvering margin is required. 1.0 G stall line shows the upper limit for 1.0 G maneuvering, actually known as level flight. If we consider a partially ballistic path we can do with less maneuvering margin. The graph depicts 0.5 G and 0.1 G stall lines.