Pilot/Controller Glossary

c. 180 degrees Autorotation. Initiated from a
downwind heading and is commenced well inside the
normal traffic pattern. "Go around" may not be
possible during the latter part of this maneuver.
AVAILABLE LANDING DISTANCE (ALD)- The
portion of a runway available for landing and roll-out
for aircraft cleared for LAHSO. This distance is
measured from the landing threshold to the
hold-short point.
AVIATION WATCH NOTIFICATION MESSAGE-
The Storm Prediction Center (SPC) issues Aviation
Watch Notification Messages (SAW) to provide an
area threat alert for the aviation meteorology
community to forecast organized severe thunderstorms that may produce tornadoes, large hail, and/or

Pilot/Controller Glossary

convective damaging winds as indicated in Public
Watch Notification Messages within the Continental
U.S. A SAW message provides a description of the
type of watch issued by SPC, a valid time, an
approximation of the area in a watch, and primary
hazard(s).
AVIATION WEATHER SERVICE- A service
provided by the National Weather Service (NWS) and
FAA which collects and disseminates pertinent
weather information for pilots, aircraft operators, and
ATC. Available aviation weather reports and
forecasts are displayed at each NWS office and FAA
FSS.
(See TRANSCRIBED WEATHER BROADCAST.)
(See WEATHER ADVISORY.)
(Refer to AIM.)