On Wednesday, 12 February 2020 15:34:50 UTC+2, Pat Russell wrote:
I would like a deeper understanding of how the LX90xx calculates ETE than can be found in para. 5.1.1.6 of the manual.

I would like to start by asking if there are any accessible documents or discussions on the topic.

As a thought experiment, how should it be done? What is required is a forecast of the weather conditions and your personal flying style for the rest of the flight.

- Do you follow strict MC speeds in calm air?
- Do you keep exact same average speed during final glide as before?
- Do you know that you will get one or several thermals exactly same as your MC setting while flying home?
- Do you fly final glide exatcly to safety altitude with no added margins at any conditions?
- Is the final glider wind identical to your all previous wind measurements, starting from first thermal after releasing from tow?

If you answered yes, it is pretty easy to calculate the ETE/ETA. If no, just forget it.