On Mon, Sep 23, 2019 at 04:45:38PM +0100, Someone Somewhere wrote:

But it seems obvious that the best solution would be some kind of
(presumably) electrical tug that could take a plane from the gate to the
point where it needs to switch to using its own engines for takeoff.

Given that the engines (I believe) turn the generators that provide
electrical power, that point is the point at which the plane is
disconnected from ground power. They need electricity to power the
radios that let them talk to the control tower, run air conditioning,
make announcements to passengers, and so on.

If you took the idea further then you could considerably optimise the
airport - planes would only need to be at gates for when passengers were
embarking/disembarking ...

You just introduced a lot of complex ground movements. And while that
might (might, not will) make more efficient use of the gates, it won't
make more efficient use of taxiways, runways, or aircraft.

--
David Cantrell | even more awesome than a panda-fur coat

Longum iter est per praecepta, breve et efficax per exempla.