In your controller training, are situations
addressed concerning aircraft
which request priority but do not declare an
emergency? Is there any
guidance in the Controllers' Handbook?

The document says (very roughly) if in
doubt handle as emergnecy even if not
declared by aircrew.

This reminds me of a time when I was
a dual Pilot Under Instruction.

I was flying the aeroplane (almost
ready for solo) when (as we later
found out) a drive gear to one of the
magnetos lost some teeth.

We were 500' AGL climbing out from takeoff.

The engine immediately lost a lot of power
and sounded very bad. The instructor took over
control and turned 180 degrees and made
a downwind landing. The engine did not get worse.
IIRC we were able to maintain altitude more or less.

I was surprised that he did not declare an emergency
and only requested clearance to land on the reciprocal
runway. The tower said nothing either but as we approached
I could see that the fire crews were out.

I did not pursue my flying and so have not really
much more experience that I had then but
I still feel that not declaring an emergency was
not the right thing to do.

He was however a military instructor which I
assume indicates quite a bit of flying experience.

He did, of course, take the opportunity to
demonstrate and talk through the issues
and techniques of downwind landing which
I had not yet covered!

The engine lost power since the faulty
mag was still firing quite a lot but not at
the right time. Given more altitude various
mag switch fiddling would have presumably
restored power.

Anyway, the point is that the UK controllers
behaved as described in the document
referred to in the previous post and
called out the crash crew even though no
emergency had been declared.