newest backup for gyro failure in IMC

In article ,
"Todd W. Deckard" wrote:

Actually, Ron you can derive a very accurate attitude reference from only
accelerometer(s).

I doubt that very much. You need roll rate information from somewhere.
Do you have a reference?

In any case, even if you can do it with just accelerometers, you need
very good accelerometers and you need an integrator, neither of which
this camera is likely to have. It almost certainly has a single
accelerometer and no integrator. All it will tell you is the apparent
acceleration, not your actual attitude.

This is how the AHRS units in a Garmin G1000 work for example. They
integrate accelerations and moments
using small very accurate mechanical sensors.

Yes, but some of those sensors are gyros. They are solid-state gyros,
but they are gyros nonetheless. (The gyros may themselves be built out
of accelerometers as components, but one way or another you have to
sense rotation rate in order to build an AHRS.)

Now, I cannot vouch for using a camera as an inflight reference :^)
However, I have wondered if some sort of
"solid state" package (or something based on the small RC helicopter gyros)
could be built that could provide
an attitude reference that you could even velcro to the glare shield.

Yes, such things exist (e.g.
http://www.icarusinstruments.com/microEFIS.html). But they are
expensive because they require multiple sensors and sophisticated
electronics to do the integration.

Maybe the camera is proof we would be close.

No, this is exactly my point. What this camera is doing is (almost
certainly -- I haven't actually looked at its technical specs) NOT the
same as an AHRS despite the fact that their behavior is superficially
similar, particularly when you are not in an airplane. That is exactly
why I think it's important to warn pilots away from trying to use this
device as a backup AI. It will almost certainly kill you.

rg