Mxsmanic wrote:
writes:
A sensor to find true north in an airplane in flight doesn't exist.
GPS finds true north. And, just incidentally, you can find true north by
looking at the sky. ANS will do that, and people can do it, too.
Not all planes have GPSes. In fact, most don't. Many of the haldheld
units fail. The failure rate for compasses is quite low. The FAA is
not likely to revise its requorements for a compass any time soon.
Thus, the reliance on magnetic north.
The isogonic lines on a chart take care of all the problems of where
the actual north/south magnetic poles are.
Documenting them doesn't really eliminate them.
Wrong again, bucko, there is nothing better for finding north in an
airplane in flight.
GPS is better, and more accurate, to name just one.
Not really. It is unreliable. Its signals can be disrupted - rendering
them useless. I don;t want my only source of reference taken away at
anyone's whim.
The only ways to find true north are celestial navigation and a true
gyro compass.
You can find true north by looking at the sky, or with GPS, or with ANS
(automated looking at the sky), or with an INS. The latter usually has to be
on the ground, although some systems support align-in-motion with a longer
setup time.
Not likely in most GA planes on most flights. Usually one is busy
flying and has no time for that stuff. Not possible on cloudy days.
You can't use celestial navigation unless you have a clear sky, an
almanac, a precise clock, and the necessary instruments to measure
celestial angles and the training to be able to use it all.
You need a precise clock to do just about any navigation. The need for the
rest is debatable, depending on how resourceful you are.
GPS could be used to indirectly find either type of north, but it
doesn't work without power, which is an important concideration
when flying a real airplane without a pause button.
Unless the airplane is a glider, you have power.
Bull****. Can you say piper cub (to name one counter example)
There is no need for electric power in a plane.
Inertial navigation requires an initial set up against something
else, constant updating measured in minutes, and again, power.
One third correct: it requires power, but engines provide power. It doesn't
have to be set up against anything else to find true north. It doesn't need
to be constantly updated; the whole idea is to be fairly autonomous.
Not in the real world. On a computer maybe...
compass is still the best, most reliable way to find north. (true or
magnetic)