Pilot/Controller Glossary

4/3/14

PCG W−1

W

WA−

(See AIRMET.)
(See WEATHER ADVISORY.)

WAAS−

(See WIDE-AREA AUGMENTATION SYSTEM.)

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 posi-

tion used for route/instrument approach definition,

progress reports, published VFR routes, visual

reporting points or points for transitioning and/or

circumnavigating controlled and/or special use

airspace, 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 AIRMET.)
(See SIGMET.)

WHEN ABLE

−

a.

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.

b.

In conjunction with a weather deviation

clearance, requires the pilot to determine when he/she

is clear of weather, then execute ATC instructions.

c.

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.
WIDE-AREA AUGMENTATION SYSTEM

(WAAS)− The WAAS is a satellite navigation system

consisting of the equipment and software which

augments the GPS Standard Positioning Service

(SPS). The WAAS provides enhanced integrity,

accuracy, availability, and continuity over and above

GPS SPS. The differential correction function

provides improved accuracy required for precision

approach.

WILCO

− I have received your message, understand

it, and will comply with it.
WIND GRID DISPLAY− A display that presents the

latest forecasted wind data overlaid on a map of the

ARTCC area. Wind data is automatically entered and

updated periodically by transmissions from the

National Weather Service. Winds at specific

altitudes, along with temperatures and air pressure

can be viewed.
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.
WIND SHEAR ESCAPE– An unplanned abortive

maneuver initiated by the pilot in command (PIC) as

a result of onboard cockpit systems. Wind shear

escapes are characterized by maximum thrust climbs

in the low altitude terminal environment until wind

shear conditions are no longer detected.
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.)