[time-nuts] GPS from a window seat

[Bill Hawkins]

Group,

Completed circumnavigation of the world via Singapore with a hand-held
Garmin 60 CSx GPS receiver.

Set it to record at 6 minute intervals, and marked waypoints. Used about 6%
of track space with 4 GB micro SD card.

Had no trouble with aircraft interference. Talked to the Captain after a 4
hour flight from MSP to LAX. He said he had no problems, and thinks GPS
receivers are quite safe. He worries about active transmitters, like cell
phones and wireless laptops.

Had no trouble getting a lock at altitude and speed. Didn't have a window
seat in the A380 from Singapore to London. About 2/3 of the way through,
over the Ukraine, I found a window I could stand by. Took about 2 minutes to
lock. Last lock was in Singapore.

Had no trouble with getting 20 foot accuracy with the receiver in a jacket
pocket near the window. Can get 10 foot accuracy when stationary. Could go
to 40 feet in some satellite configurations. Close enough for recording a
trip.

There was some discussion of hand held devices being crippled for aviation,
so that aviation units could be sold for more money. The 60 CSx will not
display GPS altitude. It only uses a barometric sensor, which gives you
cabin pressure. OTOH, the compass display uses GPS if you are moving, and
magnetic when you are standing still. No problem for a map of the course.
Cabin pressure will tell you when you have landed or leaped into the sky.

Very impressed with the performance of the receiver and antenna in that
device. Newer units don't have an antenna stub, so they may not have the
response of the 60 CSx.

Also useful for setting your watch. But you can get several inexpensive
watches and preset them for the cities that you will visit. As you are
landing, change to another watch. Saw an oil executive do that in the
Concorde in '83, with expensive watches.

That was my experience. YMMV.

Bill Hawkins