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Old May 4th 06, 08:10 PM posted to rec.aviation.ifr
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Default IFR use of handheld GPS

Peter,

John Deakin wrote about this on Avweb back in 1998.

Take a look at:

http://www.avweb.com/news/columns/182076-1.html

Tim.

On 3 May 2006 14:41:25 -0700, wrote:

Tim,

All of that sounds very reasonable to me. But so many people think
that they can't navigate direct without approved panel mount GPSs that
I thought there might be some truth in it.

So if a controller asks if I can navigate direct to some intersection
(while under IFR) I can say yes and use my handheld and that's okay? I
suppose it'll all work out, but I wasn't sure how to answer that
question a month or so ago when I was asked. So I said "we can wing
it" and his response was, "well I better give you a vector" and then I
went and "augmented" his vector with my handheld. I'm sure the
controller would have preferred that I just say yes and do it. It
would have been easier for him.

Peter

Tim Auckland wrote:
Here's my layman's understanding of this. I hope someone will jump
in and correct me if I've got something wrong,

If you're IFR en-route, ATC has three ways of directing you::

a) via an airway;
b) direct;
c) vectors;

ATC needs to have you on radar to issue (b) or (c).

You should only accept a direct clearance if you're confident you can
navigate direct.
It doesn't matter what method you plan to use to navigate direct -- it
can be dead reckoning, celestial navigation, visual (if you're VMC),
VOR, hand-held GPS, panel-mount GPS, etc.

If you're not confident you can navigate direct, then you should
refuse the direct clearance. ATC already has you on radar, so it's
typically no big deal for them to issue a radar vector instead.

What happens if you've accepted a direct clearance, and your hand-held
GPS's battereis die?
It's just the same as any other reason for being unable to navigate
direct (clouds cover the stars, you can no longer see your
destination, your ham sandwich falls to the floor...). You inform
ATC, eg:
"Cessna 12345 is no longer able to navigate direct xyz. Request
radar vectors."
(Remember, they've already got you on radar to issue the direct
clearance.)

So, it's OK to accept a direct clearance, even if you're /U, as long
as you're confident you can do the navigation.

It's also good practice to always cross-check your navigation using
some independent means.

Once again, if any of this is wrong, stupid, or illegal, please
correct me. I'm here to learn!

Cheers,

Tim.