More info:

The FAA defines a runway incursion as, “Any occurrence at an airport
involving an aircraft, vehicle, person, or object on the ground that
creates a collision hazard or results in a loss of separation with an
aircraft taking off, intending to takeoff, landing, or intending to
land.” (FAA Safety report, 2006)
http://www.faa.gov/airports/runway_s...rireport06.pdf

Note: "ANY OCCURRENCE AT AN AIRPORT"... That was in 2006.

"The FAA's evolving safety management approach will include:
- Making the transion to the ICAO standardized definition of a runway
incursion...." -ibid

"The biggest difference between the two definitions is that ICAO
defines a runway incursion as any unauthorized intrusion onto a
runway, regardless of whether or not an aircraft presents a potential
conflict. For the FAA, an incident without an aircraft in potential
conflict — such as an unauthorized aircraft crossing an empty runway —
was defined as a “surface incident” and not a runway incursion. The
new definition means that some incidents formerly classified as
surface incidents will now be classified as C or D category runway
incursions, which are low-risk incidents with ample time and/or
distance to avoid a collision." http://www.faa.gov/news/fact_sheets/...fm?newsId=9612
(effective Oct 1, 2007) [seems contradictory]

"Although the official FAA definition of a runway incursion considers
those incidents where an actual loss of separation occurs, for the
purpose of Part 139, runway incursions or runway deviations (not
involving a loss of separation) are based on any unauthorized entry of
a ground vehicle onto the movement area or safety area."
http://www.alaska.faa.gov/airports/s...ification.html

We can debate whether they should be called "runway incursions" or
just "incursions" all day long, but, where the rubber meets the
taxiway, which is at present about 75 feet behind where I'm sitting,
if you enter the taxiway without clearance, the tower, which is about
100 yards to the west of me right now, will report it as a runway
incursion and, according to them, the FAA will generally rule that it
was caused by pilot deviation.

That's quite simply how it works, right now, at the Class D towered
airport where I am presently writing this, according to the chief
pilot, the CFIs, CFIIs and ATPs who are here right now, the FSDO and
the FAA-licensed controller of the FAA control tower with whom we just
spoke.


-c