The nice thing about flying is you can go directly between airports; no following roads. But pilots often choose a more complex route to avoid mountains and in instrument conditions pilots have to follow specific airways. There's no signs in the sky, how do we navigate?

Pilotage and dead reckoning are the most elemental navigation. Pilotage just means "looking down", trying to figure out where you are by matching what you see on the ground to what's on your chart. It's remarkably difficult, particularly high up, but following roads and recognizing unusual landmarks works OK. Dead reckoning is the art of guessing where you are by what direction you've been going. It's pretty unreliable, particularly because of winds aloft, but it can give you some idea where you are.

Beacons are the historical source of airplane navigation. A VOR radio beacon tells you the bearing to a known station on your chart; cross-checking two VORs (or using DME) gives you location to a pretty precise point. Earlier beacons include NDBs, four course ranges, and beacon lights (map, current operation in Montana). The drawback to beacon navigation is you only learn your position relative to some fixed, expensive-to-maintain equipment. Also it's generally only easy to fly directly to or from a beacon, hard to fly any path.

Area navigation is the simplest way to know where you are, X marks the spot. Everyone knows GPS, it makes airplane navigation very simple. Predecessors to GPS include LORAN (RIP) and good ol' sextants, used until the 1970s. An interesting alternative is inertial navigation, in active use today in commercial aircraft and quite accurate as long as you can occasionally correct the accumulated errors with some other reference.

I pretty much always navigate via GPS: plug in the course and fly the purple line. But GPS can and does fail, so it's important to stay current with other forms of navigation. Pilotage is fun and keeps you busy long boring flights. VORs are still an important part of IFR flying. But honestly, GPS is so great it's hard to use anything else.

  2010-06-22 17:12 Z