Unhindered by the need for oxygen from the atmosphere they are suitable for very high altitude flight.

Another important aspect of high altitude flight involved physiological problems that balloonists could experience when exposed to conditions at great heights.

The gains in aircraft performance that came with high altitude flight were not significant enough to justify switching from low-altitude bombing.

After another six and a half hours of low altitude flight, they arrived back at Takhli.

During the winter the prototype performed long-range and high altitude flights.

For high altitude flight sixteen 32 litres oxygen bottles were installed.

There are very few alternatives to using terrain-following radar for high-speed, low altitude flight.

Almost half of it is concerned with earlier high-speed, high- altitude flight as a means of paving the way for the Shuttle.

Blech recognised that he could win the competition outright with a high altitude flight in one of the clouds.

However, at some airports visual approaches are not allowed for environment protection reasons as low altitude flights over populated areas produce high level of noise.