Partick:

As always, I enjoy your columns. In this one you mention "The atmospheric standard for sea level is 29.92 inches (1013.2 mb), ... "Altimeter: two-niner eight-six," for example. " and also that pilots think about fuel in pounds.

I know that English is the international language for aviation, but do pilots everywhere have to cope with English units of measure, or does the rest of the world use the metric system for aircraft load and weights, altitude, barometric pressure, etc?

Thanks for an answer & keep up the good work!

Stephen Geis

Geneva, Switzerland

and "level" at '", rather than say, "climbing" or descending to said altitude, is self exlanatory! or isnt it?

First of all, regarding BP's letter, my impression was that Mr. Smith was referring to older, piston-driven aircraft engines, not comparing turboprops to turbofans.

On a different note, take a look at this article from American Heritage magazine, originally published in 2003: http://tinyurl.com/b4bdk

It describes "railway neurosis", a phobia of sorts of train travel in the 1800s, similar to what we're talking about in relation to flying nowadays. Eventually, humans habituated themselves to the idea of train travel, and although rail crashes still make the news, I don't think they fill the average person with the sort of dread that airline disasters do. Do we experience that same moment of contemplating our mortality when we board a commuter train as we do with airplanes? How long before we habituate ourselves to flying in the same manner? When space travel becomes commonplace, and usurps our fears?

The Montreal metro also has trains which produce curiously musical sounds. According to a Montreal metro fan site (http://www.metrodemontreal.com/faq/rolling.html#threenotes):

The three-note sound (there may be more notes during a slower startup) that is produced by the MR-73 trains (orange, yellow, and blue lines) is the sound of a piece of equipment called a peak chopper. It is used to power up the motors on the train in stages, to prevent a power surge.

Coincidentally, the three notes are the same as the first three notes as Aaron Copland's Fanfare for the Common Man, one of the musical themes for Expo '67 [which was held in Montreal].

In the January 20th edition of Patrick Smith's "Ask the pilot", Smith writes,

In 2004, just under 1.9 billion people flew, and 466 were killed. That's .000000245 percent of all passengers. For 2005, it was 2 billion fliers and 1,050 casualties, or .000000525 percent.

Smith's percentage death rates are off by a factor of one hundred. 466 deaths out of 1.9 billion passengers represents a death rate of .0000245%; 1,050 deaths out of 2.0 billion passengers represents a death rate of .0000525%

I work in airport operations and ARFF at Flagstaff Airport. Imagine my embarassment when I read that airline staff told passengers waiting to board that "...one of the engines might cut out." I think it goes without saying that no carrier would launch a flight if one of the engines was about to give up the ghost.

Flagstaff sits at 7000ft. above sea level and density altitude routinely reaches 10,000ft. in the summer. As such, air carrier flights are often weight restricted as Mr. Smith points out in the article. I think the counter staff may have misunderstood what (s)he was told by the pilots. Aircraft weight, in high density altitude conditions, would have to be reduced enough to allow the aircraft to proceed through takeoff and initial climb in the unlikely event one of the engines failed during this critical phase of flight. In previous articles, Mr. Smith has shown that complete failure of a turbine engine almost never happens, but for the airlines and the FAA it is better to err on the side of caution.

Please note that this is just my opinion, and that I am not writing on behalf of the airline or airport authority.

I thought the article on why the media fixates on airline disasters very insightful.

However, as a sometimes white-knuckle flyer, I have to say maybe there is some truth to people's fear about flying. I like to work out the numbers while the plane is taxing for takeoff.

While commercial flying is probably the safest form of travel ( excluding elavators) per MILE, the numbers are very different on a per HOUR basis. According to International Civil Aviation Organization, flying on a scheduled commercial airliner in the USA has roughly 11 fatalities per million flight hours, while driving has 0.47 (Failure Associates).

So flying has a 22x higher fatality rate per hour. In other words, the risk is concentrated into a much shorter span than common transportation methods such as driving or bicycling ( which has 0.25 fatalities per million hours [Failure Associates]).

Since a significant majority of the airline fatalities happen during takeoff or landing, the risk is even more concentrated during these procedures. Something I sometimes think about as the pilot rotates.

Another distinctive sound in the passenger compartment of the A320 series, in addition to the dying dog PTU, is the "ker-chunk" heard when the brakes are released. You'll often hear it just prior to taxi.

John L wrote:

"People don't appreciate how much more reliable jets are than prop planes"

There is really nothing inherently more "reliable" about a plane powered by a propeller versus one powered by a turbofan. Aerospace engineers will take exception, I'm sure, but the engine that powers those propellers on a Dash-8 or a Jetstream turboprop is really not that different in principle from the one sitting beneath the wing of that spanking-new A320 or 737-900. Propeller-powered aircraft are remarkably efficient at lower, denser altitudes, which is one reason why regional airlines readily employ them.

An ability to see a few blades spinning in circles shouldn't be one more trigger for the flying jitters that Patrick discusses this week, nor should other everyday occurences like the cabin lights flickering when the engine generators are switched on. I was once sitting next to a very nice woman who nearly jumped out of her seat thinking something was terribly wrong when the cabin lights flickered.

Thanks Patrick, for doing a big part to help the us pay attention to the man behind the curtain, while leaving the mystique of flying intact.

-BP