Unicom: 04/06


Battery Maintenance
With reference to Its Not A River In Egypt (Learning Experiences, January 2006), I do not agree with the crews judgment to fly the airplane with a known problem. The Barons batteries were in such a low state of charge they would not crank the engines.

External power should never be used when the internal battery power isnt sufficient to start the engine(s). Dead batteries require three to four hours to recharge fully from the aircraft generating system. Therefore they are not considered airworthy in a discharged state.

Batteries that have enough power to crank and start the engine(s) will generally recharge to a reasonable state of charge prior to takeoff and should provide the required essential power for a safe landing in the event of a failure of the generating system.

Normally, batteries should be replaced when their fully charged capacity reaches 80 percent of the new rating.

Generally, aircraft are certified with the essential power requirement of 72 percent of the new battery capacity rating. That equates to a battery that is worn to 80 percent in a 90 percent state of charge

It appears that the batteries state of charge was sufficient only to keep the battery relay coil energized and to run the avionics before a total electrical power loss occurred.

Also, it was stated that the voltage regulators were the cause of the complete loss of electrical power.

It is doubtful that both regulators failed at the same time. What is more probable is that the generator or alternator fields were not energized because of the low battery voltage and the flight was made with only the available (low) battery capacity. I dont believe that the FAA certified the Baron with discharged batteries.

Please fly safe, people! Aircraft are not certified with dead batteries!

Skip Koss
Vice President of Marketing
Concorde Battery Corporation


Color, ADAHRS and Age
I love the new design. And color really makes the articles stand out. Two things: What is ADAHRS? This may be familiar to IFR folks but some of us Cherokee 140 VFR guys do not know what you are talking about.

Also, the reference on p. 14 of Januarys issue that older pilots who learned at an early age are at lower risk than those who learned at a later age. Never heard this. Can you elaborate?

Frank Barron
Rome, Ga.

The acronym ADAHRS refers to an air data attitude heading reference system. These components drive the glass-panel primary flight displays (PFDs), like the Garmin G1000, in newer aircraft. Think of an ADAHRS as a miniaturized set of airspeed, altitude, artificial horizon and directional gyro instruments.

The reference to older pilots who learned to fly at a young age being lower risk comes from a recent NTSB study, Risk Factors Associated with Weather-Related General Aviation Accidents, adopted Sept. 7, 2005. Look for a detailed article on this study in an upcoming issue.


More Color
Way to go! Adding color to your already superb publication is a great improvement!

I am a subscriber of many years, and read every issue cover to cover! Keep up the great work!

Norm Seward
Via e-mail


For years now I have been receiving your publication and have loved it very much. I also love the new color. However, I hate the glossy paper used beginning with the February 2006 issue.

Please go back to the original flat paper-because it doesnt reflect as much light, it is much easier to read. Its also much easier to write on and highlight.

I really hope that this glossy paper was just a test as it degrades your publication. The original flat paper was so much easier to read from.Thanks for listening and keep up the great publication, but get rid of that glossy paper.

James E. Pete Polen
Pittsburgh, Penn.


Turnbacks Reconsidered
I am a long-time subscriber who always reads your magazine with great interest. The majority of the time I think the information you put out is of great value to your readers.

I am happy to see that you seem to have adopted a more conservative stance on the turnback issue (Turnbacks Reconsidered, January 2006). I believe some of the key factors are that one size doesnt fit all here, and few people will bother to take the time to practice this maneuver to proficiency on a regular basis. Certainly a C-152 or Citabria will require a different reaction and numbers than, say, a heavily loaded A36 or Malibu!

The one commonality is that all these aircraft seem to benefit most from a 45-degree bank during the turnback. A steeper bank may get you around quicker, but the risk of the dreaded stall/spin accident increases, as does the problem of trying to recover from the higher sink rate generated by maintaining flying speed at the steeper bank angles.

One issue I dont think was addressed in the article involves how many degrees of turn the maneuver really requires. A 180-degree turn wont cut it unless you have a conveniently located parallel runway or a very advantageous crosswind! Without getting into the many different ways to reverse course (90/270 etc.), I think its a safe assumption that the aircraft will turn through perhaps 250 degrees (maybe more, maybe slightly less) to align with a single runway. The reason I mention this is that if someone is practicing these things at altitude and basing the successful outcome on the amount of altitude lost while turning through only 180 degrees, they may be in for a rude surprise when and if the real thing happens!

Keep up the good work.

Jim Piper
Via e-mail

You raise several good points, not least of which is to drive home the argument that not all turnback maneuvers in all airplanes from all runways are created equal. And, more than anything, I think that was the articles intent.

A key thing to remember in considering the turnback maneuver is that there are a large number of variables at work. On some takeoffs, those variables may work in favor of a successful turnback; on others, they may not.

In any case, the number of variables with which a pilot must contend in an engine-out situation shortly after liftoff are greatly reduced by landing more or less straight ahead.


Another Satisfied Customer
I have subscribed to many publications over the years, IFR, IFR Refresher, Aviation Consumer and, of course, all the other fluff magazines. Yours is the best. I really enjoy the format and the information immensely, both as a Senior Army Flight Surgeon and as a Multi-Commercial rated Senior FAA AME. It is truly excellent.

I would ask that you continue to include at least one review of a botched IFR approach or review of a difficult approach in each issue and also that you include a review of a product that can be used to enhance safety. In the past I have read articles on how handheld GPS navigators can be used in a pinch but what I really liked was your comments on redundant systems and the importance of isolated safety back-ups.

Thanks again; I will allow the other subscriptions to lapse but yours will continue to get my renewal check.

Todd Fredricks
Via e-mail

Thanks, Todd. Well do our best.


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