Re: using GPS derived altitude/heading and "attitude" displays for aircraft control

Note the caution against such use in the AIM:

AIM 1-1-19:

4. The GPS receiver verifies the integrity (usability) of the signals received from the GPS constellation through receiver autonomous integrity monitoring (RAIM) to determine if a satellite is providing corrupted information. At least one satellite, in addition to those required for navigation, must be in view for the receiver to perform the RAIM function; thus, RAIM needs a minimum of 5 satellites in view, or 4 satellites and a barometric altimeter (baro-aiding) to detect an integrity anomaly. For receivers capable of doing so, RAIM needs 6 satellites in view (or 5 satellites with baro-aiding) to isolate the corrupt satellite signal and remove it from the navigation solution. Baro-aiding is a method of augmenting the GPS integrity solution by using a nonsatellite input source. GPS derived altitude should not be relied upon to determine aircraft altitude since the vertical error can be quite large and no integrity is provided. To ensure that baro-aiding is available, the current altimeter setting must be entered into the receiver as described in the operating manual.

Bob Gardner

"Todd W. Deckard" <twdeckard@xxxxxxxxxxxxx> wrote in message news:13lfqv2cq7ido9e@xxxxxxxxxxxxxxxxxxxxx
I have seen the high end GPS units present a psuedo panel display (I am specifically refering to the Garmin 296).

It provides a DG/HSI presentation, GPS derived altitude, turn-and-bank and vertical speed.

Has anyone experimented with this to maintain level flight in lieu of actual gyroscopic instruments. I am *very*
skeptical of this, but have heard it suggested. Has anyone experimented with recovering from an upset using it?
I would be eager for first hand experiences.

In my '170, which only had a needle and ball, if you were trapped on top and the gyro failed, that all things being equal it was bravely suggested you turn to a southerly heading, and use only the rudders and wet compass to maintain wings level during the descent.

In these same heroic hanger flying sessions (when the weather was cloudy and you weren't going to fly the airplane anyway) we speculated that setting up an upright spin was the safest course of action. Spin thru the clouds and
then recover when you are visual, just like the old DH-4 air mail pilots.

I am curious if anyone has played with a hood and one of these gyro displays. Let me know.


--
"Instrument flying, I had concluded, is an unnatural act, probably punishable by God."
--Gordon Baxter


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