Definition
The amount of forward force the powerplant and propeller (or jet engine) can actually produce at a given airspeed, altitude, and power setting. It is plotted against thrust required on a performance curve to determine climb performance, with the maximum angle of climb occurring where the difference between thrust available and thrust required is greatest.
Plain English
How much pushing force the engine and propeller can deliver right now under the current conditions. The bigger the gap between what the engine can produce and what the airplane needs to fly level, the steeper the airplane can climb.
Context Anchor
Seen in climb performance discussions, especially when comparing angle of climb and the forces acting on the airplane in a climb.
Derivation
From Latin trudere meaning 'to push' (the engine pushes the airplane forward) and Latin valere meaning 'to be strong or capable.' Together: the pushing force that is currently capable of being produced.
Why Pilots Care
It determines how steeply the airplane can climb and whether it can clear obstacles after takeoff.
Intuition Check
TA does not mean the thrust the airplane needs. It means the thrust the airplane can actually produce under the conditions at that moment.
Example Sentence 1
At full throttle on a hot day at high elevation, thrust available was noticeably reduced, and the climb felt sluggish.
Example Sentence 2
At higher altitude the curve for thrust available falls, so the angle of climb becomes shallower.