Yes it can be used without a gyro based AHRS.
Let me explain as this is a bit unusual.
The XTreme (as with our larger EFIS panels) is able to estimate your attitude based on your path through the air as measured by the onboard GPS. It works out a bank and a pitch angle from this, assuming that you fly a normal aircraft (yes, trikes qualify too) and not a UFO from the planet Zork (which does not need wings).
This works very well as long as the pilot understands what he is seeing on the screen. For this reason a little bit of text appears on the screen: "GPS Flightpath - No Attitude".
This system cannot show if you're upside down. It will show a "nose down" attitude if you are close to stall (since that is where you are going - DOWN). Bank angle is related to the rate of turn and your airspeed - that is pretty convincing and even if you are slipping the resulting bank angle error is hardly noticable.
So, is this a replacement for a gyro based AHRS ?
The answer is: It depends on your mission.
If I am flying mostly VFR and just need something to keep me upright in the event I get surprised by having to go through a bit of cloud, I'll go to the satellite page and make sure I've got plenty of those birds above me and I would then confidently use the GPS based attitude to guide me. No problem, it's just as good for this as a normal AHRS and it has one important advantage - it does not drift so it is more stable if I experience turbulence in the cloud. It has disadvantages, sure it has - if the turbulence gets so bad that I end up in uncontrolled flight and am tumbling, the GPS based attitude is useless. But to be fair, the gyro based attitude is not going to save you either as it will very quickly go wrong as maximum turn rates are exceeded and measurement errors build up quickly.
This new attitude system is as good as any other in the hands of a pilot that understands the principle it works on and it is just as valuable as tool in the cockpit as an altimeter. This is not an idle statement, I have personally tested this back to back with a gyro based AHRS in the same aircraft at the same time. It works and it works very well.
This system in fact has another aspect to it:
It serves as a backup to any other gyro based system giving a completely independent view on your attitude. This makes it extremely valuable as a cross check source for a gyro based system including dual AHRS systems if you need a tie-breaker.
If you go on the net and search a bit for this kind of thing, you will find some scathing attacks on GPS based attitude systems (which, as far as I can tell where first used at Nasa), one interesting page I found from a maker of gyro based AHRS systems. This is ironic since a lot of the modern gyro based AHRS systems actually use GPS based attitude to aid and correct errors in the gyro based system (look for example at Crossbow AHRS systems, many of the aided systems are used in expensive, certified systems) - all we did is take it one step further...
The bottom line for our typical microlights/LSA is: No need for an expensive gyro system (unless you really want it), you can have a fancy EFIS system that does not have to hide behind anything out there for a price that is simply outstandingly good.
Rainier
CEO MGL Avionics
