AVmail: May 5, 2003

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Reader mail this week includes comments about improper props, perilous GPS and more.


Guns In The Cockpit (Yet Again)

Up until now I have tried to keep my opinion on this issue to myself. But, after reading Mr. Shaw's April 28 letter on the subject I feel compelled to comment.

I mean no disrespect to Mr. Shaw, but please, please, please do not drag what is, in my opinion, pseudo-science and made-up statistics, into this debate. The science and statistics are well-known, substantiated by centuries of everything from running prisons to utilizing firearms in combat operations.

The dangers of arming staff inside a secured environment, particularly with limited training, are so well-known and widely accepted that they are literally acknowledged in the provisions of the statute. Read the statute carefully and you will see that the only place lawmakers are truly comfortable with the firearms in question being deployed is when the pilots are safely locked inside the cockpit.

One does not need to be a math wiz to know that the chances that any of these firearms will be used as a last line of defense against terrorists battering down a newly reinforced cabin door are very small. And no calculator is required to determine that the chances of an airline pilot being accidentally shot in the head by a co-worker while flying will no longer be zero.

But, as with the recent confiscation of my toenail clippers before boarding a commercial flight to Japan, the purpose of this statute is not "safety." The purpose is to make a significant portion of the population (pilots and otherwise) "feel safer." Obviously, "feeling safer" and "being safer" are not always the same thing. But, increased public confidence might have a positive impact on an ailing aviation industry, and critics of the statute should at least keep that in mind.

Joe Fitzpatrick


The Perils of GPS

There is a huge trend of "victimization" in the USA where people generally seek to fault someone or something for their problems rather than accepting responsibility for their own actions. That is the sense that I got from the recent article about The Perils of GPS. I inferred that the author "blamed" the complexity of the GPS and the lack of auto-switching in the #1 nav indicator for he and his instructor missing the localizer. I have forgotten to switch the indicator from GPS (which I used enroute) to NAV for the ILS approach in IMC, but I accept this totally as pilot error. I was never off course, however. Let me explain why the author shouldn't have been either.

To enhance situational awareness, I set up the GPS unit direct to the NDB that served as the final approach fix ...

An excellent idea. When setting up to fly an ILS with the KLNxx GPS, I nearly always set the FAF as the next waypoint. But there should be another step after that.

... we noticed the little button labeled NAV/GPS at the top of the panel. The GPS mode was selected! In other words ... the course displayed on the CDI was an arbitrary GPS course and not the intended localizer course.

This is where the deficiency is shown. Why was the GPS course arbitrary? The course displayed should have been specific: the inbound course for the ILS. Notice the author's own words later in the article:

The OBS mode suspends the automatic sequencing of waypoints and allows the pilot to fly a specific course, often selected using the OBS knob on the primary CDI.

The "hold" or "suspend" that the author focuses on as what OBS mode does is only half the story. He writes the rest in the second half of the above sentence, but he didn't apply it. The specific course or "bearing" set by the Omni Bearing Selector (lest we forget what OBS means) should have been the inbound course for the ILS being flown. Common good practice when flying an ILS is to set the inbound course with the OBS knob even though we know that a CDI displaying a localizer is unaffected by the actual course selected. So when using OBS mode, set a meaningful specific course; don't just "pause" the sequencing.

By all means, fly responsibly with the nav indicator selected to display the correct source of input (GPS/NAV/LOC) as appropriate. But if you actually Select a Bearing in OBS mode, and if your active waypoint is on the final approach course (such as the FAF), the GPS course displayed will overlay the localizer if you forget to switch the nav indicator.

Tim Holloway


The reason given to me [for not requiring automatic switching from GPS to ILS guidance] was that critical GPS guidance could be lost without the pilot being aware of it!! My question to that is, "What about the Localizer?" Answer: "The pilot is responsible to assure he has the appropriate radio set up and identified for his approach." This from the southern region FAA (covering Florida where New Pipers come from) two years ago. There's that finger I was talking about!

Bob Ferguson


NTSB Publishes Recommendations On Hartzell Props

This NTSB warning should be taken very seriously. Two propellers they ordered for my customer were done incorrectly, and at least one they did for another former employer has been inspected by the NTSB and found to be not done correctly. In my case, the props had been done six years ago without being put on the plane (Travelair). I had them sent to American Propeller for reseal and they found the props to be in a dangerous condition, which got the NTSB involved.

Bob Butt


Comments on Columns

This is probably a tech issue, but I was wondering if we can respond to the authors' columns? There is no area at the end of the article to post your comments. I like the new format, just didn't know what happened to this feature. Thank you so much for your site, I look at it several times a day, and it contains exceptional information.

Jon Grief

AVweb responds ...

That was an error when we changed to the new Web format on May 1. We're trying to get that system activated again.

Kevin Lane-Cummings
Features and AVmail Editor