Aero-Tips!
A good pilot is always learning -- how many times have you heard
this old standard throughout your flying career? There is no truer
statement in all of flying (well, with the possible exception of
"there are no old, bold pilots.") It's part of what makes aviation
so exciting for all of us... just when you think you've seen it
all, along comes a scenario you've never imagined.
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master CFI and all-around-good-guy, to bring our readers -- and us
-- daily tips to improve our skills as aviators, and as
representatives of the flying community. Some of them, you may have
heard before... but for each of us, there will also be something we
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the practical test.
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ground-bound readers to the concepts and principles that keep those
strange aluminum-and-composite contraptions in the air... and allow
them to soar magnificently through it.
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Remember... when it comes to being good pilots, we're all in this
together.
Aero-Tips 02.19.06
AWOS provides potentially vital information about weather in the
vicinity of airports. What’s information is
available? What are the system’s limitations?
AWOS
The Automated Weather Observation System (AWOS) provides weather
observations 24 hours a day without human involvement. AWOS reports
wind, ceiling, visibility, temperature, dew point, altimeter
setting, and any recorded remarks such as Notices to Aviators
(NOTAMs). AWOS is a “modular” system with several
upgrade options available, reporting:
- AWOS A: Altimeter setting.
- AWOS I: Altimeter setting plus wind
speed, direction and gusts, temperature, dew point, and density
altitude.
- AWOS II: AWOS I plus visibility and
precipitation.
- AWOS III: AWOS II plus cloud height and
sky condition.
- AWOS IIIP: AWOS III plus present
(prevailing) weather.
- AWOS IIIPT: AWOS IIIP plus lightning
detection.
- AWOS IIIPTZ: AWOS IIIPT plus freezing
rain detection.
- AWOS IV: AWOS IIIPTZ plus a Runway Surface
Condition Sensor.
Since many AWOS units
are privately or state-owned, options (and reported information)
vary. See the Airport Facilities Directory for the type used
at your destination.
Advantages of AWOS:
- Objective observation to 10,000 feet AGL within 25 miles of the
reporting point
- 24-hour availability
- Near-real-time updating
- Data added to the Flight Service briefing and forecasting
network
- Radio and telephone access for pilots
- Permits FAR 135 approaches at non-towered airports (note: most
charter and airline Ops specs require airport weather reporting to
begin an instrument approach)
Disadvantages of AWOS
- Many AWOS installation options report limited information
- Averages some weather data
- Detects clouds only straight up from, and visibility in
immediate vicinity of, the sensors
- Omits reporting of some transient weather, e.g., variable cloud
ceilings
- Terrain or other local features may limit observations
- No human oversight of reported data (in most cases)
Aero-tip of the day: Anticipate the
weather information available at your destination airport, and the
limitations on AWOS reports.