WA -- WST
WA-
(See AIRMET.)
(See WEATHER ADVISORY.)
WAKE TURBULENCE- Phenomena resulting from the
passage of an aircraft through the atmosphere.
The term includes vortices, thrust stream turbulence,
jet blast, jet wash, propeller wash, and rotor
wash both on the ground and in the air.
(See AIRCRAFT CLASSES.)
(See JET BLAST.)
(See VORTICES.)
(Refer to AIM.)
WARNING AREA- (See SPECIAL USE AIRSPACE.)
WAYPOINT- A predetermined geographical position
used for route/instrument approach definition,
or progress reporting purposes, that is defined
relative to a VORTAC station or in terms of latitude/longitude
coordinates.
WEATHER ADVISORY- In aviation weather forecast
practice, an expression of hazardous weather conditions
not predicted in the area forecast, as they affect
the operation of air traffic and as prepared by
the NWS.
(See SIGMET.)
(See AIRMET.)
WHEN ABLE- When used in conjunction with ATC instructions,
gives the pilot the latitude to delay compliance
until a condition or event has been reconciled.
Unlike "pilot discretion," when instructions
are prefaced "when able," the pilot
is expected to seek the first opportunity to comply.
Once a maneuver has been initiated, the pilot
is expected to continue until the specifications
of the instructions have been met. "When
able," should not be used when expeditious
compliance is required.
WILCO- I have received your message, understand
it, and will comply with it.
WIND SHEAR- A change in wind speed and/or wind
direction in a short distance resulting in a tearing
or shearing effect. It can exist in a horizontal
or vertical direction and occasionally in both.
WING TIP VORTICES-
(See VORTICES.)
WORDS TWICE-
a. As a request: "Communication is difficult.
Please say every phrase twice."
b. As information: "Since communications
are difficult, every phrase in this message
will be spoken twice."
WORLD AERONAUTICAL CHARTS-
(See AERONAUTICAL CHART.)
WS-
(See SIGMET.)
(See WEATHER ADVISORY.)
WST-
(See CONVECTIVE SIGMET.)
(See WEATHER ADVISORY.)
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