Planes flying low along the border with Mexico can often slip through Norad's radars, which were designed to spot high-flying bombers.

But the radars were designed to spot high-flying Soviet bombers, and are blind to aircraft flying below 10,000 feet.

American forces relied on high-flying bombers in the initial stages, for fear of exposing AC-130 gunships or helicopters to Stingers.

They appeared to have moved antiaircraft guns into the area, and fired on unreachable high-flying American bombers.

Taliban gunners furiously fired antiaircraft shells, but they exploded thousands of feet below the high-flying bomber.

The Welkin was a twin-engine high altitude design to intercept attempts by high-flying German bombers to attack Britain.

The high-flying bombers would have full fighter escort but the low-flying bombers would have to use stealth to avoid interception to and from the target area.

The Soviet Air Force, equipped mainly for low-level interception and ground-attack roles, was able to do little to hinder the high-flying bombers.

Operational Requirement F.155 was a specification issued by the British Ministry of Supply for an interceptor aircraft to defend the United Kingdom from high-flying supersonic bombers.

Firing trials involved launches against simulated targets of various types, from cruise missiles to high-flying bombers.