Can GPS be *too* accurate? Do I need some XTE??

Cub Driver ) wrote:

I am a certificated American pilot, and have been for six years. I
have never flown a VOR course and never expect to. I fly in New
Hampshire, Maine, and Massachusetts. I have about 350 hours.

Is this VFR or IFR?

I mainly file and fly IFR in the Northeast US and I have learned that if
I am flying to or from Boston or anywhere near NYC, I must file and at
least start flying airways. The controllers will offer direct where
possible, but the volume of traffic during the peak hours often prevents
this.

In my experience, there have been a few times where the only way I could
get off the airways was to cancel IFR, weather depending.

--
Peter

Peter Duniho ) wrote:
: GPS increases the chances of collision, by reducing the average error. But
: the issue did already exist with VOR navigation. Keep in mind that GPS
: error is still going to be on the order 10 to 30 meters or so, just from the
: position information standpoint, and then on top of that you still have the
: problem of the airplane being kept exactly at the intended position (even
: with an autopilot, there's going to be some slop, and not all pilots are
: using autopilots in conjunction with their GPS navigation).

The GPS error you have quoted is relative to a fixed point on the ground.
Most modern cheap GPS recievers in the same region looking at the same
sats with differential corrections are within meters of each other
and with good processing can produce a relative position within a few
inches.

The way to deal with this is to simply move the GPS course .1 nmi
to the right. This means if your doing a 90 degree turn over a VOR
using a GPS, you should make your turn .14 nmi away from the VOR
and you should be able to see it out the left window.

At this point it won't matter much considering the GA autopilot slop
but things could change in the future and now is a good time to
start putting these things in place.

but there are more an more aircraft flying in the skys that don't
but things could change in the future and now is a good time to
start putting these things in place.

-tim
http://web.abnormal.com

Y'All,
To those of you who view this offset GPS program as the latest, I
would like to add the following.

At near the end of WWII when I was a 21-year old Corporal I was
the operator/mechanic of a radar bombardment simulator/trainer as a part of
the 58th Bomb Wing Training Center (B-29) on Tinian
The device was called the Supersonic Trainer and made possible simulations
of actual bombardment runs over Japan. In the week or so prior to the
dropping of the bombs I was told to put the Nagasaki
map into the Trainer.

The trainer was running in conjunction with the APQ-23 radar system. This
was the most advanced radar bombardment system of the war and was still the
standard over five years later. Among its capabiities was to program offset
bombing.. By dialing in the azmuth and distance of a target from a radar
visible target such as a lake we could fly as though bombing the lake but
hit the target. This is where
all the offset navigation came from.

Incidentally the Nagasaki bomb missed its aiming point by three miles. If
you want the full story go to my web site at the very end
of the IFR section. 7.9++ www.whittsflying.com
Gene Whitt