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.

FMI: Aero-Tips