This is to avoid overflying a heavily defended target, or to distance the attacking aircraft from the blast effects of a nuclear (or conventional) bomb.
Release usually occurs between 20° and 75° above the horizontal, causing the bomb to be tossed upward and forward, much like an underarm throw of a ball.
Although "pop-up" bombing is generally characterized by its low-level approach, the same technique of a toss starting from level flight can be used at any altitude when it is not desirable to overfly the target.
The bomb continued upward for some time in a high arc before falling on a target which was a considerable distance from its point of release.
[3] Author and retired USAF F-84 pilot Richard Bach describes such an attack in his book Stranger to the Ground: The last red-roofed village flashes below me, and the target, a pyramid of white barrels, is just visible at the end of its run-in line.
To counter air defenses en route to the target, remaining at a low altitude for as long as possible allows the bomber to avoid radar and visual tracking and the launch envelope of older missile systems designed to be fired at targets overflying the missile site.
By executing a "pop-up" loft, on the other hand, the pilot releases the munition well outside the target area, out of range of air defenses.
After release, the pilot can either dive back to low altitude or maintain the climb, in either case generally executing a sharp turn or "slice" away from the target.
"Dive-tossing" is generally used at moderate altitude (to allow for the dive) when the target, for whatever reason, cannot be designated precisely by radar.
Thus designated, the pilot can then begin a climb, lofting the bomb at the target from a distance and regaining lost altitude at the same time.
[4] While deployed in Europe with NATO, RCAF CF-104 fighter-bombers carried a Toss Bomb Computer until their nuclear role was eliminated by the Canadian government effective 1 January 1972.
The integration into the FCC simplifies the pilot's workload by allowing the same bombing mode (CCRP) to be used for level, dive and loft bombing, providing similar cues in the pilot's displays regardless of the tactics used, since the computer simply sees it as the release point getting closer.