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Pilot's Handbook of Aeronautical Knowledge
Aviation Weather Services


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Pilot's Handbook of Aeronautical Knowledge



Table of Contents

Chapter 1, Introduction To Flying
Chapter 2, Aircraft Structure
Chapter 3, Principles of Flight
Chapter 4, Aerodynamics of Flight
Chapter 5, Flight Controls
Chapter 6, Aircraft Systems
Chapter 7, Flight Instruments
Chapter 8, Flight Manuals and Other Documents
Chapter 9, Weight and Balance
Chapter 10, Aircraft Performance
Chapter 11, Weather Theory
Chapter 12, Aviation Weather Services
Chapter 13, Airport Operation
Chapter 14, Airspace
Chapter 15, Navigation
Chapter 16, Aeromedical Factors
Chapter 17, Aeronautical Decision Making




Precipitation targets provide stronger return signals
therefore the radar is operated in the Precipitation
mode when precipitation is present. A faster antenna
rotation in this mode allows images to update at
a faster rate, approximately every 4 to 6 minutes.
Intensity values in both modes are measured in dBZ
(decibels of Z) and depicted in color on the radar
image. [Figure 12-1] Intensities are correlated to
intensity terminology (phraseology) for air traffic
control purposes. [Figure 12-2 and 12-3]

Example of a weather radar scope.
Figure 12-1. Example of a weather radar scope.

WSR-88D Weather Radar Echo Intensity Legend.
Figure 12-2. WSR-88D Weather Radar Echo Intensity Legend.

2. FAA terminal doppler weather radar (TDWR), installed
at some major airports around the country, also aids in
providing severe weather alerts and warnings to ATC.
Terminal radar ensures pilots are aware of wind shear,
gust fronts, and heavy precipitation, all of which are
dangerous to arriving and departing aircraft.

WSR-88D Weather Radar Precipitation Intensity Terminology.
Figure 12-3. WSR-88D Weather Radar Precipitation Intensity

3. The third type of radar commonly used in the detection
of precipitation is the FAA airport surveillance radar.
This radar is used primarily to detect aircraft, but it
also detects the location and intensity of precipitation
which is used to route aircraft traffic around severe
weather in an airport environment.

4. Airborne radar is equipment carried by aircraft to
locate weather disturbances. The airborne radars
generally operate in the C or X bands (around 6
GHz or around 10 GHz, respectively) permitting
both penetration of heavy precipitation, required for
determining the extent of thunderstorms, and sufficient
reflection from less intense precipitation.

Advancement in satellite technologies has recently allowed for
commercial use to include weather uplinks. Through the use
of satellite subscription services, individuals are now able to
receive satellite transmitted signals that provide near real-time
weather information for the North American continent.

Satellite Weather
Recently private enterprise and satellite technology have
expanded the realm of weather services. Pilots now have
the capability of receiving continuously updated weather
across the entire country at any altitude. No longer are pilots
restricted by radio range or geographic isolations such as
mountains or valleys.

In addition, pilots no longer have to request specific
information from weather briefing personnel directly. When
the weather becomes questionable, radio congestion often
increases, delaying the timely exchange of valuable inflight
weather updates for a pilot's specific route of flight Flight
Service Station (FSS) personnel can communicate with only
one pilot at a time, which leaves other pilots waiting and
flying in uncertain weather conditions. Satellite weather
provides the pilot with a powerful resource for enhanced
situational awareness at any time. Due to continuous satellite
broadcasts, pilots can obtain a weather briefing by looking at
a display screen. Pilots have a choice between FAA certified
devices or portable receivers as a source of weather data.