On Monday, a FedEx cargo jet crashed and burned at Narita Airport outside Tokyo. Both crew members perished, and the accident garnered worldwide attention thanks to spectacular, if grisly, video footage that showed the plane bouncing, cartwheeling, then skidding down the runway in a great rooster tail of smoke and fire.
Shortly after the accident, I began scrolling through the various breaking-news reports. As usual I was wincing at every turn. Among the more egregious snippets was this from a reporter at the Associated Press:
"Investigators said the accident may have been caused by low-level turbulence or 'wind shear,' sudden gusts that can lift or smash an aircraft into the ground during landing, said Kazuhito Tanakajima, an aviation safety official at the Transport Ministry."
That is about the worst and most cartoonish definition of windshear I have ever heard. Was this a translation issue, lazy editing, or both?
For the record, there is no need to put the term "windshear," whether in its contracted form or as two separate words, in quote marks (in aviation circles it almost always appears as a single word, sans quotes, and the press should follow suit). Not any more than we need to put the word "turbulence" in quote marks. But never mind that, what is windshear? It's a common buzzword in the aftermath of air disasters, but few people, journalists included, really understand it.
Windshear is a sudden change in the velocity and/or direction of the wind. Doesn't sound very serious, does it? And it's not, usually. Garden-variety windshears are extremely common and seldom harmful.
One particularly virulent form, however, called a microburst, is another story. Microbursts are localized, downward-flowing columns of cold air, typically encountered at low altitudes -- even on the runway -- in and around powerful thunderstorms. As the air mass descends, it disperses outward in different directions. Planes are not "smashed to the ground," but if a headwind suddenly shears to a tailwind during takeoff or landing, they can suffer a dangerous loss of airspeed and lift. During the 1970s and 1980s, microbursts were accountable for a trio of tragedies in the United States that helped usher in a new generation of windshear-detection technology. Microbursts are now relatively easy to avoid (though the technology is not foolproof and the judgment of pilots remains important).
Hazardous shears can also occur in clear weather if winds are exceptionally gusty. There were no thunderstorms around Narita at the time of the FedEx incident, but wind gusts were at gale force, hitting up to 50 miles per hour.
But that alone, I'm pretty sure, was not the culprit. All aircraft are subject to maximum crosswind and tailwind limits that pilots will not exceed, and even the most vicious gust is highly unlikely to cause a catastrophic upset. There are strong suspicions that known instability issues of the MD-11 itself were also at play.
The MD-11 has unusually high approach speeds, and as part of a strategy to help improve fuel economy, it was designed with a disproportionately small horizontal stabilizer -- the aft set of wings that helps control a plane's nose-up, nose-down motion, or "pitch." According to one MD-11 pilot I spoke with, these characteristics, together with the effects of something known as a Longitudinal Stability Augmentation System, make the jet unusually difficult to land. They also make it easy for pilots to over-control during bounced or otherwise unstable landings, which in severe cases can lead to a total loss of control and a subsequent crash.
In the footage from Narita, we see the aircraft touch down, then bounce back into the air. On a landing bounce, a crew can either allow the plane to touch down a second time, or immediately apply go-around power and climb away, depending mainly on the severity of the bounce. Anything substantial generally entails a go-around. The FedEx plane suffered a very substantial bounce. But rather than climb away, the jet pitches downward, then slams violently back to earth, nose first. Understanding what happened in those few seconds after the bounce is the key to understanding the accident. We don't yet know, and until we do the list of possibilities is long: If the plane's speed had dropped below a certain point, pitch authority may have been compromised to the point where the crew lost control altogether. The effects of automatic spoiler deployment, engine spool-up time and perhaps improper control inputs could also have conspired to make abandoning the landing difficult or impossible.
"A bounced landing recovery is pretty difficult on many airplanes," explains an MD-11 pilot. "You need to act quickly, but the engines need some time to spool up, and everything happens fast."
And don't forget those gale-force gusts and the chance of windshear. In the throes of recovering from a violent bounce, an otherwise innocuous shear can be disastrous.
For whatever reasons, the FedEx jet hits the ground again, hard. The impact is so strong that the tail section and left wing appear to fracture, at which point the jet rolls upside down and bursts into flame.
Another MD-11 pilot I spoke to believes that the plane's landing gear design was also a potential factor. "The main gear assembly of the MD-11 is more structurally robust than is found on other jets," he explains. "This sounds like a good thing, but during certain impacts, such as in a very hard landing, rather than shearing away and helping disperse the impact, the gear strut will transfer the full force directly to the wing spar, leading to collapse of the wing itself and loss of the airplane. It's too much strength in the wrong place."
Boeing, which inherited the MD-11 several years ago through its takeover of McDonnell Douglas, says the gear design is safe and will not transfer excessive impact forces to the wing, but it's worth noting that this was the third MD-11 -- the second for FedEx -- to be involved in a flip-over crash in which the wing separated after a hard landing.
The MD-11 is a derivative of the widebodied McDonnell Douglas DC-10. It first flew in 1990. Although the model is fairly new and advanced, most have been converted to freighters, with only a limited number still in passenger service. (That aforementioned AP story incorrectly stated that none remain in passenger service.) Performance shortfalls and cost issues caused most passenger carriers to replace them with more efficient models, such as 777s and A330s. Cargo airlines operate with a different cost-per-mile metric, and the planes have been quite profitable in that realm.
Finnair and KLM are two carriers that continue to carry passengers in MD-11s, albeit in small numbers. If you find yourself booked on one of these planes, please don't panic. There is no need to cancel your reservation. MD-11s have been operating for almost 20 years and have completed hundreds of thousands of safe landings, in both good and bad weather. Even if what happened at Narita is, on some level, owed to quirky design, that does not make the aircraft categorically unsafe.
And another, desperate plea to the media, the AP in particular: Is there anything I can do or say, aside from the numerous letters I've sent and columns I've written, that will persuade you to please cease and desist from your confusing use of terms "pilot" and "copilot"?
Once again: All commercial jets operate with a minimum of two pilots, a captain and a first officer. The latter is known colloquially as the copilot, but he or she is not an apprentice or a helping hand. First officers perform just as many takeoffs and landings as captains do, and are fully qualified to operate the plane in all regimes of flight.
Use of the term "pilot" is fine, but only as a generic reference to either crew member. To cite "the pilot" at exclusion of the other pilot (as was done to nauseating excess in the aftermath of the US Airways Hudson River incident), is misleading and incorrect -- not to mention rude to first officers like me.
And with that out of my system, let's move on to coverage of another fatal airplane crash.
On Sunday, a single-engine plane went down near Butte, Mont., killing all 14 people on board, including a group of children. Investigators are looking at icing as a potential culprit, possibly exacerbated by overloading. This is nitpicky, but I have to take issue with the AP's Matt Gouras, who wrote:
"The crash is the fourth major plane accident in slightly more than three months." He goes on to list incidents involving Colgan Air (Dash-8 went down near Buffalo, N.Y.), Continental Airlines (737 skidded off runway), and US Airways (Airbus A320 lost both engines and landed in river). "Before the Buffalo crash, there hadn't been an accident involving a commercial airliner in the United States in which there were fatalities in more than two years."
The plane in Montana was a Pilatus PC-12, a Swiss-built turboprop designed primarily for corporate and air-taxi service. It has one engine, and requires only one pilot. It's not quite a private plane, but certainly closer to a private plane than to the transport category planes flown by Colgan, Continental and US Airways. Technically, planes like the Pilatus are sometimes operated commercially, but under a completely different set of guidelines than those governing the airlines. Thus, with all due respect to the seriousness of 14 people dying, I don't believe the Montana crash belongs in the same category with those others.
And lastly, so that I can't be accused of harping only on the negative...
Whether or not you have an interest in commercial flying, you owe it to yourself to read William Langewiesche's recent Vanity Fair piece on the mysterious 2006 midair collision over the Amazon between a Boeing 737 and a corporate jet. (Yours truly covered it here.)
Nobody gets it better than Langewiesche, one of America’s preeminent reporters, a successful author, and a former pilot himself. (He is the son of Wolfgang Langewiesche, author of a famous art-of-flying manifesto called "Stick and Rudder.") The Vanity Fair story delves into air traffic control protocols, anti-collision cockpit avionics and so on. Those are challenging topics, and he is almost flawless (even if I fail to understand his strange animosity toward Joe Sharkey, the New York Times business travel writer -- and Ask the Pilot fan -- who was aboard the corporate jet that struck the 737). I found only a couple of questionable passages and one or two very minor mistakes (it's Amazonica Control, not "Amazonia" Control).
When Langewiesche takes on an airplane story, he pretty much nails it. His work is immaculate and exhaustive, and he's an outstanding wordsmith to boot.
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Do you have questions for Salon's aviation expert? Contact Patrick Smith through his Web site and look for answers in a future column.
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