Altitude and Altimeter

Altitude and Altimeter. As everyone knows, an altimeter is of utmost importance when flying. The pilot needs to know the altitude of the ground he's flying over. He needs to know the altitude of the surrounding hills and mountains, if flying in a mountainous region. He needs to know the altitude of any airplanes flying in the vicinity, and he obviously needs to know his own altitude. To do these things, the pilot checks his altimeter.

Our airplane, a kit-built, Vans RV7, has several instruments capable of reading altitude. One altimeter looks like the one at left. Although this type is old technology, often called a "steam gauge" instrument, it's on the instrument panel for redundancy. If the electronic gadgets hubby relies on for altitude readings were to give out, he could use this.

Otherwise, he mostly relies on the Dynon and the AvMap to give him altitude readings as well as a host of other necessary information. The electronic devices give a colored, moving map display. When flying near something higher than we are, those objects (mountains, usually :) ) turn red. Everything else is green.

Commercial airliners fly at an altitude of 35,000-40,000 feet, generally. They are pressurized, but if the jet were to lose cabin pressure, little oxygen masks would drop down to enable passengers to breathe at these high altitudes.

Our airplane is not pressurized, nor do we have supplemental oxygen masks. We can fly only to 12,000-14,500 feet, and only for a maximum of thirty minutes. Otherwise you suffer from hypoxia, oxygen deprivation, and will pass out.

The highest we've flown the RV7 was 11,000 feet, when we crossed the Rocky Mountains and then flew down into Great Falls, Montana.

During most of the year, we fly only a couple thousand feet above ground level. Our local terrain is 2400 feet, and so we seldom fly above 5000 feet. Summer air conditions--updrafts and downdrafts--cause turbulence. The higher you go, the smoother the ride, and so we generally fly a little higher in the summertime than during any other season. Even then, we seldom go above 8000 feet ... and to do all of this, you need to keep a steady eye on your altimeter readings.

Have you ever tried to keep an airplane at a steady altitude? Whenever hubby hands me the stick and asks me to keep the airplane at a certain altitude, I'm always surprised at how hard it is. In the blink of an eye, practically, you can lose, or gain, several hundred feet.