"Marc Adler" wrote in message
oups.com...
The pilots say things like "See traffic at 12 o'clock, but can't tell
if it's a regional carrier or not. Please advise." This sounds like the
pilot is expecting to be able to recognize the plane.

At two miles, it's usually the case that one can recognize the general type
of aircraft. Distinguishing a twin turboprop from a single-engined piston
plane, for example. But it's dependent on a variety of things, including
the pilot's own vision (only required to be corrected to 20/40) and ambient
conditions (whether the called traffic is viewed against the sky or ground,
current visibility, position of the sun, etc.). Two miles is certainly
getting toward the edge of reliable identification.

Generally speaking, a clarification request from ATC such as what you've
heard resolves the question. A pilot can go ahead and proceed following the
traffic they believe to be the correct traffic, and with the request for
clarification ATC knows to keep an eye on things and make sure the pilot is
following the traffic they expected them to (if ATC has a radar display,
this can be done quite easily).

Pete