AviationBanter - View Single Post - Absolute lowest altitude you can fly (legally)

**Mxsmanic** · January 6th 07, 06:59 AM posted to rec.aviation.piloting,rec.aviation.student

writes:

Knots are not dimensionless in aviation. A knot is one nautical
mile per hour, and that nautical mile is the distance corresponding to
one minute of latitude at the equator.

Yes, but that is largely incidental today, particularly for east-west
movements away from the equator. Anyone using that relationship for
dead reckoning, for example, can get into trouble if he's not very
careful.

Anyone using lat/long and some spherical trig (like the old guys
who crossed oceans used sextants to determine their position) will
make use of these things.

I don't think too many pilots use sextants today. I think an
increasing number of pilots don't know how to do anything except look
at a moving map display, or set an autopilot.

The lazy ones
among us (or like me, the ones really poor at math) will use GPS, which
does the same thing.

Yes. But what you don't use, you lose. And I don't think pilots are
taught how to use sextants, anyway. Although I've heard that early
airline navigators and pilots used them--which is why some older
aircraft have little windows above the pilots, for shooting the stars.

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