I will just add one point that just occurred to me.

"Peter Duniho" wrote in message
...

a) that a landing aircraft failed to obtain a clearance to land, and

No. That's the whole point. A controller may well clear an airplane to
land right on top of you. You just don't know.

In the US ATC is permitted to anticipate separation in landing clearances:
"3-10-6. ANTICIPATING SEPARATION

Landing clearance to succeeding aircraft in a landing sequence need not be
withheld if you observe the positions of the aircraft and determine that
prescribed runway separation will exist when the aircraft cross the landing
threshold. Issue traffic information to the succeeding aircraft if not
previously reported and appropriate traffic holding in position or departing
prior to their arrival."

"American Two Forty-Five cleared to land, following United Boeing
Seven-Thirty-Seven two mile final, traffic will depart prior to your
arrival."

In the UK (and I think in the rest of Europe), such clearances are not
permitted. A landing clearance indicates that the runway *is* clear and
will remain clear of other traffic until the aircraft has vacated it.



Thus the level of confusion/incompetence/distraction required for the
controller to "clear an airplane to land right on top of you" would be very
much greater in the UK. I can imagine a scenario under the US regime where,
if the departing traffic were waiting for an IFR clearance and it were slow
to arrive, a controller might fail to resolve the unanticipated conflict.
In the UK it would require a major mistake as to fact, not just a mistaken
expectation.