Commercial pilot Ryan explains that pilots use the plane’s radio altimeters to know the exact height of the airplane above the terrain below. They especially rely on this data during approaches ...

Mode C transponders also transmit altitude information, obtained from the aircraft’s barometric altimeter. An improved surveillance radar technology is Mode S, for Mode Select. Each Mode S ...

Almost every full-scale plane has a variometer as part of its ... making it easy to adapt the altimeter portion of the project to any language. Finally, a standard family radio service radio ...

But the systems had limitations. GPWS relied on the airplane’s radio altimeter, which determines the aircraft’s altitude by bouncing a radar signal off the ground and measuring the duration of ...