Ask the pilot

Gasp! I can't breathe! These bogus media stories about airflight are going to make my head explode during landing!


Patrick Smith
June 3, 2005 11:30PM (UTC)

Recent media coverage of a series of light-plane accidents has me scratching my head. First, on May 21, a Cessna 172 on a sightseeing flight plummeted onto the beach of New York's Coney Island, killing all four people aboard. Reports cited "an engine problem." One Fox News affiliate spoke of the plane's motor having "stalled out."

Then last weekend, a single-engine plane went down during an air race in Oklahoma. The small craft had "lost power," according to newspaper and television sources.

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And on May 31, a privately owned twin-engine turboprop crashed and caught fire at Teterboro Airport in northern New Jersey. More blather about "engine trouble."

Now, although engine problems sometimes precipitate a crash -- usually by distracting an inexperienced pilot who proceeds to turn a difficult situation into a nonsurvivable one -- they do not, by themselves, cause planes to go spinning out of the sky. Perhaps, for instance, that racer in Oklahoma was in the middle of some high-G maneuver when a malfunction caught him by surprise, but whether it's a two-seater or a 747, any airplane is able to glide successfully sans power. Even the heaviest jetliners glide routinely during so-called idle thrust descents, and believe it or not, the glide ratio of a large jet -- altitude lost to horizontal distance traveled -- is usually better than that of your average private model (the one caveat being that it must accomplish this descent at a considerably higher speed).

The Teterboro incident is especially perplexing, as the aircraft had two engines. Multi-engine commercial airliners, as regulars to these pages should know, are certified to climb, avoid obstructions, and otherwise remain aloft following the failure of a powerplant at the worst possible moment. But even a private twin should, at the very least, maintain a stable course should one of its props cease turning. Rest assured there was more to this accident -- and the others too -- than a simple sputtering of cylinders.

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So, if nothing else, there you have three potential entries for my ever-expanding media errata log. (This isn't a column about engines, see, it's a column about the articles that follow them.) OK, maybe I'm overanalyzing. If a pilot radios a message saying he's got an engine on the blink, or if witness accounts tell of the same, that's quite a natural thing to report. Nonetheless, the talk of proverbial engine trouble that comes on the heels of so many accidents reinforces the irritating fallacy that a dead engine necessitates a deadly crash.

Which it does not.

Honest to god, I'm not half the neurotic crank I might seem, and it'd be foolish to expect reporters to expertly grasp each and every nuance of a field rich with mysterious procedures and confusing terminology. Still, it's my job to make note of such infractions (and in fact this column was born out of frustrations over media coverage of safety and security issues after Sept. 11). We live in a time when people have diminishing trust in the press, and there's the danger of assumptive extrapolation: If aviation stories are routinely off kilter, why not those covering medicine, politics and so forth?

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With that out of the way, let's keep going. Somewhat less offensive, if still inaccurate, was a May 29 Associated Press piece that credited Delta Air Lines for being "the nation's third largest airline." Actually, measured either by raw passenger totals or RPKs (that's revenue passenger kilometers, a standard industry gauge), Delta is the second-largest airline. The Atlantans were previously a third-place finisher but have moved up thanks to United's struggles. Measured by those same criteria, Delta is now first runner-up not only in the United States, but in the world.

Passenger totals for 2004, if you're keeping score, went like this:

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1. American Airlines 91.6 million
2. Delta 86.9 million
3. Southwest 81.2 million
4. United 70.8 million
5. Northwest 55.4 million

Granted, that's a petulant quibble, but the Associated Press has been on probation for several months now, and I demand the highest standards from them. You might recall my earlier hissy fits in which the AP was taken to task for, among other errors, misidentifying a regional jet, confusing tailwinds with headwinds, and claiming that more than 300 people were able to fit inside a 737. Over the winter I counted factual errors in five AP stories over barely a month's time. (I've offered my services free of charge as a fact-checker, as most of the mistakes are pretty simple and quickly spotted. No reply yet to my letters.)

Getting off the AP's back for a moment, over at the New York Times on May 31 we discovered an amusing little piece about the troubles at Air Zimbabwe.

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"Shunned by Western travelers," Times reporter Michael Wines explains, "Air Zimbabwe has tried to make money by turning east, serving Beijing and Singapore as well as Dubai. But Zimbabwe's poor economy and the airline's generally creaky planes have dissuaded customers."

Well, OK, except a look at the books shows that Air Zimbabwe's 767s are of comparable vintage to those at most other airlines. Creaky? That's open to interpretation, I guess. The carrier's oldest aircraft, a Boeing 737, was constructed in 1986. Those tuned in to this column during the past few weeks know 19 years is relatively fresh for a jetliner, and considerably younger than those DC-9s and DC-10s found at Northwest, for example.

"Not long ago," the piece continues, " [Air Zimbabwe's] in-flight magazine ran an article assuring ticket-holders that rumors that the airline was not safe to fly were unfounded."

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Good for the magazine, since Air Zimbabwe hasn't suffered a fatal incident since 1979, when it was still called Air Rhodesia. The article doesn't mention this, leaving open the implication that perhaps those rumors are not so unfounded.

Game for more?

Here's one from the BBC.

"Air passengers risking health," yelps the headline. "More than half of air passengers are starved of oxygen, a study finds."

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That certainly sounds alarming, until you click over, read the story, and realize just how misleading and inflammatory it is. And this is the BBC, not Fox News, the New York Post, or one of the U.K. tabloids.

The article discusses a hospital study that determined oxygen levels in airline passengers' bloodstreams decrease by approximately 4 percent on some flights. On the ground, O2 levels are about 97 percent, dropping to an average of 93 percent during flight.

Except, what does that mean, exactly? To anybody who understands the workings of aircraft pressurization these numbers are neither a shocking surprise nor much to worry about. Planes cruise where the air is thin and oxygen is relatively scarce. The fuselage is therefore pressurized to replicate conditions near the ground. Notice I say "near" the ground. An airplane flying at, say, 35,000 feet will maintain a cabin altitude not of zero feet, but of somewhere around 8,000 feet. Maintaining a cabin at sea level itself is unnecessary and would put undue stress on the airframe, and so interior pressure is kept at a certain height above sea level.

Sitting there at the equivalent of 8,000 feet, yes, your blood oxygen will probably register less than it would on the ground. But unless some preexisting condition is already affecting your health, this is hardly the stuff of danger -- not any more than standing on a street corner in Mexico City, at a lofty 7,500 feet above sea level, is inherently hazardous to one's well-being (well, it may be, though for different reasons).

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"This has become a greater problem in recent years," laments Dr. Susan Humphreys, the study's lead researcher, "as modern aeroplanes are able to cruise at much higher altitudes."

That's baloney. No matter how high any aeroplane flies, the resultant cabin pressure is always within a certain comfort zone, and under no conditions will it break the aforementioned 8,000 feet, the regulatory limit. Should something go wrong and the cabin climb higher, cockpit alarms are triggered and eventually masks start popping from the ceiling.

(And for the record, the composite fuselage structure of Boeing's new 787 will allow for greater pressure differentials during cruise, meaning a lower and more comfortable cabin altitude.)

If nothing else, the BBC piece nurtures people's fears and bewilderment over what, exactly, aircraft pressurization is all about. (Note the link to the right of the headline: "Why millions are terrified of flying.") Chief among the public's many misconceptions is the idea of pressurization as a sort of physiological hell -- the pressurized fuselage cocked and ready to destroy the plane and everybody in it. Hollywood has been of no help here, with its renderings of bursting windows and wild panic when, for reasons that are never fully explained, those plastic masks come dangling.

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The sole purpose of pressurizing a plane is to provide you with enough oxygen to breathe normally. That rarefied, high-altitude air is great for fuel economy, but not so great for breathing. Pressurization simply squeezes it back together, increasing the number of oxygen molecules per unit of air.

Yet of all the e-mails I've received over the past couple of years, perhaps the most fantastical of the lot involve pressurization. "If a plane wasn't pressurized," began one of the first queries ever sent my way by Salon readers, and later addressed in my book, "would my eyes pop out?"

I thought I'd put such silliness to rest, but apparently not everybody was paying attention...

I was told the story of a man having a heart attack on a plane. The pilot made a steep descent for an emergency landing, during which, as the story goes, the man's head exploded. I understand that a person whose heart has stopped pumping would have a collection of oxygen in the head and a steep dive would reduce cabin pressure quicker than usual. Could this have happened?

I've checked on Snopes, and there's nothing about exploding heads on airplanes. Yet. Let's cut this story off before it has a chance to propagate. (Albeit with a mild disclaimer: I'm in no way a doctor, and there's a small risk of pulling my own version of an AP/BBC gaffe. Special thanks to Tom Daly, airline pilot and scuba diver extraordinaire, for assistance with the following.)

First, there's no way a stopping heart will cause the dissolved oxygen in your body to come out of solution. Meanwhile, the only place you have dead-air space is in your sinuses -- the nasal passages, inner ear, and in the sensitive tissue surrounding your head -- and these are the only places where changes in pressure are felt. If you don't chew gum, swallow, or somehow equalize the pressure, it will occasionally cause discomfort, as anyone who has ever flown with a cold can tell you. But unless you have a blasting cap lodged up your nose, there's no danger of your head exploding.

Think about scuba diving. At 33 feet you have already doubled the pressure on your body. Go to 100 feet and it's four times that of the surface. What do you feel? Nothing, as long as you equalize your sinuses (ears).

Atmospheric pressure at sea level is about 14.9 pounds per square inch. In an airplane, typical cabin pressure at cruise is about 8,000 feet, or 11 psi. With less than a 4 psi difference, even an instant drop to sea level wouldn't cause serious harm. Plus, in a descent, the pressure within the aircraft is increasing, not decreasing, so if anything there would be an inward or crushing effect.

I rode a Canadair regional jet from Washington to La Guardia. Once we boarded, it was announced the flight would operate at only 9,000 feet because the pressurization system wasn't working properly. We were told that our ears might pop more than usual. I have been to Quito, so I know I can breathe at 9,000 feet, but the news was disconcerting. Was I wrong to be freaked out?

What you experienced was unusual but not unprecedented. I used to captain a regional turboprop, and occasionally when things were acting up we'd go unpressurized. On this particular model, the inflatable gasket that surrounded the main cabin door had a habit of unexpectedly deflating. (It would occasionally do so with a noise that sounded like a dozen Harley-Davidsons accelerating at once: harmless but startling.) The cabin would steadily depressurize and we'd be forced to descend below 10,000 feet for the remainder of flight. Then, for the next leg or two, we'd get a deferral to fly sans pressurization until repairs could be coordinated. Don't forget, prior to the 1950s or so, when advanced technologies allowed aircraft to take advantage of upper altitudes, all flights were unpressurized.

The need to stay low will wreak havoc with fuel consumption, so this kind of thing is practical only on short trips and is pretty much unheard of with larger, mainline aircraft. Unless you're on a specially designated maintenance-only ferry flight, you won't be going unpressurized at 9,000 feet in a 767.

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Patrick Smith

Patrick Smith is an airline pilot.

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