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.
Aero-News has called upon the expertise of Thomas P. Turner,
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
might never have considered before, or something that didn't
"stick" the way it should have the first time we memorized it for
the practical test.
It is our unabashed goal that "Aero-Tips" will help our readers
become better, safer pilots -- as well as introducing our
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.
Look for our daily Aero-Tips segments, coming each day to you
through the Aero-News Network. Suggestions for future Aero-Tips are
always welcome, as are additions or discussion of each day's tips.
Remember... when it comes to being better pilots, we're all in this
together.
Aero-Tips 04.29.06
A student of mine sent me an e-mail:
Hi Tom,
What does it mean when ATC reads the Radar weather and responds "no
echoes"?
I replied:
That means that they see no evidence of precipitation on their
radar scope.
Radar works by broadcasting a powerful radio beam that reflects,
or "echoes", off obstacles it encounters. The reflected energy
travels back to a receiver antenna where it is detected by the
radar set—what is called a primary display. This allows the
receiver to determine the bearing of the obstacle (the direction
relative to the receiver). Since radar energy travels through the
atmosphere at the speed of light (approximately 186,000 miles per
second), accurately timing the transmission of the beam and the
receipt of an echo permits calculation of the range, or distance,
from the receiver to the object detected.
The word "radar" is an acronym for this entire process: RAdio
Detection And Ranging.
Most Center radar images recognize airplanes well, but not
weather. Approach radar uses wavelengths that are better at
detecting weather. Both Center and Approach radar usually
"declutter" the display by filtering out weather they do receive,
and also primary displays—showing instead only transponder
signals, radio transmissions triggered from aircraft when the
transponder is "hit" by the radio beam.
ATC reports "no echoes"
If an Air Traffic Controller reports "no echoes," then, you need
to consider the source of the information. Is it a Center radar?
Chances are precipitation would have to be very heavy, and/or close
to the radar transmitter, to be detected at all. Are you talking to
Approach Control? They may have weather echoes filtered from their
screens. Are controllers referencing the standard FAA radar report?
Plotted radar data may over an hour old. (See figure, and note
the effective time at the upper left -- I downloaded this at 1822Z,
or 37 minutes after the observation time). Is it a NEXRAD or
Doppler image they’re referencing? Chances are this
information is recent and pretty accurate, unless you’re in
an area where terrain can block the radar signal, or you’re
very distant from the radar transmitter.
Note: Last time I visited an Approach
Control facility -- admittedly about four years ago -- it was
stormy and controllers were taking turns running to the break room
to watch radar displays on The Weather Channel to better assist
pilots.
Aero-tip of the day: Ask not only if ATC sees
precipitation, but also what type of radar they’re
referencing, and how recently the display was created. In the US,
you can generally get better weather information by calling Flight
Watch on 122.0 or the appropriate high-altitude frequency.