Unicom: 12/05


Miles And Mics
In Octobers Accident Probe, Miles To Go, you note, The pilot was cleared for the ILS approach to Runway 5 at SPA and released to the local advisory frequency. Oh goodie: Another frequency change from ATC at low altitude, low speed, in actual IMC at 10:00 p.m. Another dead pilot.

Controllers and the ATC system have been killing pilots for generations with frequency changes and clearance deliveries at the most awkward possible times.

Just as the nosewheel lifts off the pavement, they give me a frequency change. As the aircraft is handed off from one controller to another, the frequency should be handed off also. Let the controllers change frequencies.If they become spatially disoriented, there are no consequences.

Hal Stiles
Via e-mail

Every time I get into a dispute with a controller Im tempted to ask how fast his or her chair is moving. That said, its still up to the pilot to manage the cockpit workload and balance the priorities of communicating and navigating with aviating. Sometimes, its not easy. But its always satisfying to do right.


Carbon Monoxide
Thank you for your recent article in the October 2005 issue summarizing a 2003 accident involving a Twin Comanche (Miles To Go). In it you twice mention the NTSBs comments regarding the 11 percent carbon monoxide (CO) levels in the pilots blood, but leave these comments hanging.

There could be a few reasons for this finding. At night in late October in this region of the country, he may have been using a defective heater. We might presume that the NTSBs specific exclusion of CO poisoning in the probable cause of the accident would deter from this possibility. The toxicology also showed a 0.35 g/ml cyanide level. Both these findings are not inconsistent with a heavy smoker.

Finally, cyanide and CO are both known to come from burning aircraft interiors, especially 40-year-old ones. The medical examiners cause of death is listed as: cardiorespiratory arrest secondary to internal hemorrhage, carbon monoxide intoxication, and probable concussion with diffuse severe thermal burns. This implies, whether conscious or not, the pilot was breathing in the burning aircraft for a short period of time before succumbing.

This is, of course, just my own interpretation of the limited data. I mention this only because your readers may have been left with the impression that the pilot might have crashed due to CO intoxication from a faulty heater, which was probably not the case.

Thank you again for your great publication.

Stephen Wagner, M.D.
Via e-mail

As you correctly surmised, we left in the NTSBs references to the pilots CO exposure because we were somewhat confused. And we wanted to spread the confusion. Thanks for your comments, and for helping us understand these findings.


Stuck Mic
I would like to respond to your editorial on the stuck microphone in Octobers issue.

For the last 40 years, the land mobile (two-way radio) industry has supplied first in hardware, and now in software, a circuit called a time-out-timer (also called a transmission limiting timer). Police radio, taxis, and other users have had this as a built-in part of the radio units since many of them have the habit of throwing the microphone on the seat and getting it stuck between the seat cushions.

When the microphone is keyed, the time-out timer keys the transmitter. After the time set in the timer, usually 2-3 minutes, the timer circuit unkeys the radio, and sends a tone to the radio speaker that is unmistakable (loud). As soon as the microphone is unkeyed, everything goes back to normal. The circuit can be built with a small handful of parts, or now just added into the radio software. Where has the avionics industry been for the last 40 years?

I enjoy your magazine. Keep up the good work.

Jay Underdown
Via e-mail

Id guess the omission of this circuit/software from aviation radios is as much the responsibility of the FAA as it is avionics manufacturers, perhaps more so.

Regardless, its interesting that, here in the year 2005, we still havent figured out a way to deal with a stuck mic.


Experiencing Stalls
This comment is motivated by Tom Onetos article Stalls Revisited, September 2005.

It is a shame, bordering on downright dangerous, that full stalls, right through the break and into fully developed spins followed by recovery, are not a mandatory part of flight training. There is nothing more disorienting to a pilot unfamiliar with spins than the face full of swiftly rotating terrain that accompanies an unintentional spin, no matter how it is entered. It is so disorienting that more than a few pilots, some of them quite experienced, have gone headfirst into the earth full of perplexity and fright at the strange sight of the ever-growing spinning scene out front.

There is only one remedy for that danger, and that is experience. To be safe, everyone who flies should be taught to enter spins from a variety of situations, to know what they feel like as they start and when they get going, and how to get out of them safely.

Of course, it goes without saying that everyone should understand the circumstances that lead to spins and have experience of a variety of them. Current training does include this to a very small extent, but most real spins are inadvertent-practice in rapid recognition and correct reaction is badly needed.

David Fox
Via e-mail


Prop Failures
Tom Turners excellent article, Top Prop Traps (October 2005), reminds us all of some important aspects of propellers in GA aircraft. I have often demonstrated the single feathering he describes to illustrate improved glide capability. But it would be good for readers to realize that since, as he points out, such props will fail in flat (high-rpm) mode, coupled with the fact that oil pressure is required for the prop control to operate as advertised, an engine failure mode that results in oil pressure loss would effectively lock the prop in the flat (high-rpm), draggy position.

In other words, because several causes of powerplant failure would remove the pilots ability to coarsen the pitch (or even seize the engine and crankshaft), youd better count on the 1700-1900 fpm descent described, not the more favorable one of 700-900 (for the A36).

Duncan Patterson
Via e-mail


High-Altitude Ops
A recent newspaper article highlighted the recent fatal crash of a 28,212-hour pilot. The crash occurred during takeoff from a high-altitude dirt airstrip. The article states that pilot error was the cause of the crash; the pilot set the mixture control too lean. This was a turbocharged aircraft.

I am a Bonanza pilot, although I havent flown in years. If memory serves me correctly, the procedure for takeoff from high-altitude strips varies depending on the model of Bonanza (and engine) you are flying; for some you must lean for takeoff, for others you do not.

Even though I think I have read about this subject on more than one occasion in Aviation Safety, I do not remember an entire article dedicated to this issue. This recent crash might provide a good opportunity (and reason) to review this matter in your publication.

Doug Finney
Via e-mail

While we wouldnt put too much faith in the general medias coverage of a light plane accident, your point is well-taken. Well be covering high and hot operations in an upcoming issue. Stay tuned.


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