@Sebastian_G, does it have to be via GDL?
For such a rare occurences it might be enough to add consumer-grade INS system to some existing product, just a new model, and display it on a tablet or phone.
You know, there is really smart guy in Germany, Dr. Golze, do you know if could we ask him to add a new feature to the ADL devices? ;)
Yes it is obvious the ADL app would be the ideal platform 
but you need a better AHRS than the cheap solid state ones, if you want to actually navigate with it.
Peter wrote:
Yes it is obvious the ADL app would be the ideal platform but you need a better AHRS than the cheap solid state ones, if you want to actually navigate with it.
Question is for how long at a time would you want to use it for navigation? I think the cheap ones are OK for about 15-30 min, which is OK to help you if GNSS just died…
arj1 wrote:
Question is for how long at a time would you want to use it for navigation? I think the cheap ones are OK for about 15-30 min, which is OK to help you if GNSS just died
The AHRS sensor in most of the ADL devices is called BNO055 (there are two types for supply chain issues but both are very similar). I did not yet build an AHRS but the amount of drift seen on the gyros and also the amount of noise on the accelerometers make me guess it is impossible to build any meaningful INS platform with such sensors.
An INS should be able to detect a change in altitude wind through the slight acceleration experiences by the plane. To make this happen a much better sensor would be required. Most probably an old school platform with a certain minimum mass for damping is a requirement.
A cheap solution could be to use an air data computer plus a download of GFS wind predictions before the flight. Then plotting the flight path second by second might work fine for a while.
We have a few other threads here on AHRS / solid state gyro products. Some of these, supplied as temperature stabilised modules, are way better than the bare yaw gyro + accelerometer chips as used in e.g. the Sandel SG102 (see the avionics internals thread for the classic AHRS approach which has not changed much in 20 years). Whether they are ok for “navigation” depends, of course, on the “navigation” 
Probably ok for driving a moving map (initialised with GPS) for long enough to climb out of a canyon. But the end user price of such a package would be well over 1k. @ultranomad had some interesting info on the latest modules and I probably posted some. Much of that market is driven by automative needs where you need a faster response than you get with a GPS receiver alone. But with lots of effort and temperature stabilisation (an oven) and throwing lots of software at it to compensate for drift etc, the 3 digit priced modules are about 100x better than the raw chips.
Look here for some non-cheap products.
Peter wrote:
Probably ok for driving a moving map (initialised with GPS) for long enough to climb out of a canyon.
It can also be improved by including magnetometer data (+ IGRF map), air data, and constraining the ensemble of data from all sensors with aircraft’s equations of motion.
