"Thank you for your answers, very clarifying.

And what about Doppler navigation, would it be possible on small drones? I have these questions about dead reckoning because it is not always that I can count on good GPS signal."

"For sure not suitable for a small drone, but since 50 years have passed from that model and now we have such small and cheap units (which I find incredible) I just asked if they would be capable of doing dead reckoning (500m long flights).

It…"

"Example of inertial system from the 60's, 2 mile error on 500 mile long flight:
http://en.wikipedia.org/wiki/LN-3_Inertial_Navigation_System"

"Regarding my comment on dials to adjust speeds (V & H), altitude hold, etc, it comes from my experience as an aircraft pilot, it is completely different to fly holding the control yoke or using the autopilot dials. Using the autopilot the plane is…"

"Thank you for commenting JB,
I'm probably thinking about the autopilot 'hold' modes because to me it seems much easier to fly these things from the inside rather from outside ;-)
The hold modes would be there mostly as 'dampers' against oscilations,…"

"Just in case someone is curious about how Boeing deals with redundancy:http://www.citemaster.net/get/3c501aaa-39d5-11e4-9cb6-00163e009cc7/..."

"Sure Ben, you are completely right.
Even on modern, big jets, serious issues can happen when onboard computers get conflicting data. And the conflicting data can lead even the pilots in the wrong direction.
For example, in recent years some Airbus…"

"Hi John, thank you for your reply.
I guess the main thing I wanted to bring is this concept of flying 'manually' trough the autopilot (as I know it), which would be the guy who keeps the flight very stable.
It's a very common thing in airplanes,…"

" Sorry for jumping in your technical discussion, I'm a former airline pilot, now as a photographer I'm researching before buying my first drone.

I think there is a lot to be made on the user interface side yet.

Probably the most popular use for…"