Ask the pilot

Death and survival in the skies over Brazil and England: Two New York columnists show us the ups and downs of air disasters.


Patrick Smith
October 6, 2006 3:30PM (UTC)

The biggest aviation news stories of the past several days take us on a journey from Brazil to England, with stops along the way at two of the world's most influential newspapers.

We begin in Brazil with the crash of a Boeing 737. Shortly before 5 p.m. local time on Sept. 29, Gol airlines Flight 1907, bound from the port city of Manaus to the capital, Brasilia, with 155 people on board, collided in midflight with a smaller executive jet carrying seven crew and passengers. The smaller plane, damaged in the left wing and horizontal stabilizer, remained flyable and made an emergency landing at an air force base. The 737, apparently rendered uncontrollable, plunged into the Amazon jungle -- in a region so inaccessible that indigenous Kayopo Capoto-Jarina Indians used machetes to help emergency crews reach the scene. There were no survivors, making it the worst-ever crash in Brazilian aviation history.

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Both aircraft were effectively brand new. The Boeing, a 737-800, had been delivered to the airline on Sept. 12. (Registered PR-GTD, it can be seen here fresh from the assembly line.) The executive jet was a Legacy 600, a derivative of the popular ERJ-145 regional jet manufactured by Brazilian aerospace giant Embraer. The plane was on its delivery flight to ExcelAire, a private aviation firm based at MacArthur Airport outside New York City.

All seven occupants were Americans, including New York Times "On the Road" travel columnist Joe Sharkey, who was researching a story. For me, coming across Sharkey's name in the newspaper was one of those spit-out-your-coffee moments, for Joe happens to be an avowed reader of this column. He and I have shared occasional correspondence. (Several months ago he was nice enough to contribute a complimentary blurb to my home page.)

"We were flying at 37,000 over the Amazon," Sharkey tells "Ask the Pilot." "Nobody saw the 737. One pilot and one passenger saw only a fast-moving shadow. "We were headed straight, minding our own business, when bang!"

At that point, four feet of the Legacy's left winglet was sheared away, along with several inches of the horizontal stabilizer. Winglets are the upturned tips affixed to the airfoils of many modern aircraft. They increase efficiency and enhance aerodynamic performance by smoothing the mix of high- and low-pressure air at a wing's outermost extremity. Horizontal stabilizer refers to the aft set of wings mounted on or near a plane's tail. Winglets are expendable -- if you're going to lose something, have it be a winglet (or maybe an engine, provided it doesn't slam into something on the way off). But aircraft quickly lose their flyability when stabilizers are banged up. Had a larger portion been lost, or had the elevator -- the stabilizer's hinged portion, used to control a plane's up and down pitch -- been impacted or jammed, chances of survival would have been substantially reduced.

It might seem counterintuitive that the much larger and heavier 737 was fatally impacted while the smaller Embraer survived. But it's not about weight, size or even speed, necessarily. What matters is where, exactly, the damage occurs, and to what extent. Nobody yet knows where the 737 was struck. The Legacy's winglet may have cut away a stabilizer, or a critical portion of the wing.

According to Sharkey, loosened skin panels of the left wing began to separate during the half-hour descent that followed. "We remained stable throughout, but because of the wing deterioration the crew considered ditching before we reached that air force base. They brought us down hot, in a wide spiral to minimize stress on the left wing. We were flying over dense, dense Amazon jungle. The sun was low to our left. The forest canopy was dark."

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I don't know if he and the other six realize how fortunate they were. "I would be told time and again in the next few days," Sharkey recounts in the Times, "that nobody ever survives a midair collision." Actually, it has happened a few times. In 1972, a Convair 990 jetliner was clipped by a DC-9 in the skies above France. All 68 on the DC-9 perished, but the Convair managed a safe landing at a military base. But Joe is basically correct: Midair collisions are not normally so forgiving, and for one party to emerge unscathed is definitely the exception and not the rule.

The worst of them was the 1996 collision near New Delhi, India, between a Saudia 747 and a Kazakh cargo jet. All 349 passengers and crew were killed in what remains history's third-worst aviation accident. The Kazakh pilots had disobeyed instructions from controllers, and neither airplane was equipped with collision-avoidance technology. In 2002, a DHL freighter collided with a Bashkirian Airlines passenger jet over the Swiss-German border. Both planes fell to the ground, killing 71 people. Confused by conflicting instructions from air traffic control, the Bashkirian crew responded incorrectly to its cockpit collision warning system, descending into the path of the DHL 757. An understaffed control sector, a disabled alarm system and even a malfunctioning phone line were contributing factors. Prior to that, in what remains Europe's deadliest two-plane catastrophe, 176 were killed when jets belonging to British Airways and Inex-Adria, a Yugoslavian carrier, hit each other over Zagreb in 1976. (Of course, the worst accident of all time, anywhere, was the 1977 ground collision of two 747s in the Canary Islands.)

In America, 82 people died, including 15 on the ground, after an Aeromexico DC-9 was struck by a private plane over Los Angeles in 1986. The single-engine Piper had wandered into LAX airspace sans permission. Eight years earlier, a Pacific Southwest Airlines 727 collided with a Cessna over San Diego. A snapshot of the plummeting PSA jet, its right wing aflame, is one of the most remarkable aviation photos ever taken.

The two California crashes helped usher in the anticollision technology called TCAS (Traffic Collision Avoidance System, or "Tea-Cass" in aviation parlance) that is standard now in almost all passenger airliners, large and small. Air traffic controllers monitor a plane's altitude and location as relayed by a cockpit unit called a transponder, while TCAS goes a step further, using those same transponder signals to present a graphic representation of nearby aircraft to pilots. A typical TCAS display, superimposed over a cockpit's weather radar screen, looks like this. A more advanced version would look like this. TCAS issues progressively ominous oral and visual commands once thresholds of distance and altitudes are crossed. If two aircraft continue to fly toward each other, their TCAS units will work together, ultimately vocalizing a loudly imperative "Climb!" instruction to one, and "Descend!" to the other.

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An emerging, satellite-based technology known as ADS-B, currently under testing, promises to provide crews and controllers with even greater protection. An enhancement of ADS-B, called CDTI (Cockpit Display of Traffic Information), has been installed in over a hundred aircraft flown by cargo giant UPS.

"Collision avoidance based on ADS-B would be infinitely superior to TCAS," says Jim Haney, a UPS captain. "TCAS is merely a transponder add-on. With CDTI and ADS-B, aircraft could 'see' each other from many miles away, and accuracy could allow for lateral as well as vertical avoidance maneuvers."

Down in Brazil, the biz jet and the 737 were both equipped with TCAS and sophisticated transponders, and were under air traffic control supervision. Local authorities claim the Legacy pilots were flying at the wrong altitude, had ignored a command to descend and may have turned off their transponder. Why they would have done so is a mystery. A disabled or nonfunctioning transponder (typically two are on board) would prevent TCAS from issuing the proper advisories. Brazil has seized the two U.S. pilots' passports. With little else to go on it's tough to speculate on what went wrong. According to a Brazilian newspaper, the planes were being handled by separate ATC sectors (not "control towers," as some have stated; those handle traffic only in the vicinity of an airport) -- one from Manaus, the other from Brasilia. In the United States, controllers in separate facilities do not clear traffic through the same airspace.

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I feel terrible for the airline. Gol -- the company's full name is Gol Transportes Aéreos -- is a low-fare upstart that in less than six years has captured nearly a third of Brazil's air traffic. Last year, Gol's orange-and-white 737s carried 13 million people in a tussle for market share with the country's mainstay carriers -- the feisty TAM (19.5 million) and the perpetually beleaguered Varig (12.9 million). Over 10 percent of Gol's passengers are first-time fliers.

And while I don't mean to sound flip or disrespectful toward those who've been killed in midair collisions, speaking as the airline pasionado -- one who wishes to be as close as possible to every important event, even the tragic kind -- I'm a tad jealous of Joe Sharkey. Any aviator -- even an erstwhile one, and especially one who writes a weekly column on the world of flying -- covets a battle scar or two for his résumé. My own close call, you might recall, was comparatively light on the carnage, and heavy on the melodrama.

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For another intriguing story, we turn to Sharkey's counterpart over at the Wall Street Journal. There, Scott McCartney, author of the Journal's "The Middle Seat" feature, has reignited controversy surrounding the strange saga of British Airways Flight 268.

That was the London-bound Boeing 747 that suffered an engine malfunction moments after takeoff from Los Angeles in February 2005. After shutting down the errant power plant and conferring with company technical staff, the crew opted to continue with three functioning engines rather than return to LAX. Several hours later, having consumed more fuel than anticipated, the aircraft, carrying 18 crew members and 352 passengers, made an emergency diversion to Manchester, England, where it landed safely. The incident made headlines and touched off a small hurricane of debate. The Federal Aviation Administration promptly filed civil enforcement charges against British Airways.

In August the FAA announced it was finally dropping the case after 18 months of investigation. The agency's decision came after British Airways agreed to revise its engine-out policies on flights from the United States. Separate investigations by two U.K. air safety boards had already exonerated the crew of Flight 268.

Ostensibly reporting on the FAA's decision, McCartney's Journal piece has circulated far and wide during the past several days -- though not necessarily because it is well researched and informative. It's both of those things, yes, but it's also misleadingly sexed-up, with an incendiary headline and overtones of danger that, for the most part, never existed. The problem is mostly in the packaging: "After Engine Blew," sings the headline, "Deciding to Fly On 'As Far as We Can.'"

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That "as far as we can" bit is the article's money shot. It's lifted from a conversation between air traffic controllers and Flight 268's captain shortly after takeoff. The controllers are informed of the decision to press on, and they are surprised. The snippet gets your attention, doesn't it, conjuring up the image of a crippled 747 striking out boldly across the North Atlantic, the pilots clenching their teeth. Except the reality was nothing like that, and while there's some potential hazard in flying a 747 to Europe on three engines, there's the more imminent danger to public perception by taking air-to-ground dialogue out of context and shaping it into a tabloid-style headline.

McCartney transcribes a large portion of the air-to-ground transmissions, taken from tapes obtained by the Journal through the Freedom of Information Act. The tapes, we're told, help to "flesh out" the incident. Actually, they flesh out almost nothing. For the lay reader, there's some voyeuristic novelty in trying to decipher what sounds like candid chatter, but in truth it offers little insight into the crew's decision-making process.

Ultimately, neither the tapes nor the published report from Britain's Air Accident Information Board, completed last June, reveals much that hasn't been known since the beginning:

When barely 300 feet off the ground, the Boeing 747 -- the exact ship, registered G-BNLG, is shown here in a lovely departure shot -- suffered a compressor surge in its No. 2 engine. Per checklist procedure and operational policy, the engine was shut down. Note: The motor did not "explode," "burst into flame," "catch fire" or otherwise "burn" as described in numerous accounts. Actually, McCartney's description comes closest. To say the engine "erupted in a spectacular nighttime burst of flame" is a tad over the top, but such is the nature of a jet engine. Anomalies like surges and compressor stalls, which are relatively common and seldom if ever deadly, are known to manifest themselves with loud noises and, sometimes, vivid plumes of flame. Check out the shot of this Boeing 767 enduring what is presumably a compressor stall.

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A 747 can fly just fine with three engines -- and in most conditions two -- though it will suffer altitude and speed penalties. Working together with company technical staff, the crew recalculated its projected en route fuel burn, and determined it would remain within all regulatory parameters. Rules mandate that a plane have enough fuel to reach its destination; continue to its designated alternative airport(s); then still have enough left over for approximately one hour's flying time (the precise margin varies). This, plus any contingency fuel for anticipated delays or holding patterns. Consumption is tracked carefully, with measurements taken at regular intervals -- usually when crossing lines of longitude -- and compared against anticipated values on the flight plan.

With all of that accounted for, the crew chose to keep going rather than circuit back to LAX for a precautionary landing -- one that would have required jettisoning hundreds of tons of kerosene. They would spend the next five hours over North America monitoring tank levels (there are eight in the standard 747-400), with dozens of diversion opportunities had projections proved faulty.

As it turned out, tailwinds over the Atlantic were lighter than forecast. Fuel burn grew higher than anticipated, and the pilots also became concerned that a portion of remaining fuel might be unusable because of a tank transfer problem (a worry that investigators said was unfounded). Upon making landfall over the U.K., they decided to divert.

In the words of McCartney, the emergency landing at Manchester took place "as the crew worried about running out of fuel." Editors fashion headlines, but it's a bad idea, particularly for a 10-year veteran of the airline beat, to use simplistic phrases like "running out of fuel" to describe scenarios he knows are quite complex. The concern wasn't "running out of fuel" in the literal sense. The concern was falling behind the regulatory buffers outlined above. Once this happened, they changed course for Manchester. They were not running on fumes. The rules are there to prevent crews from running on fumes. A diversion would be a possibility from the outset, and the pilots and British Airways knew that. That's what was meant by the quip about going "as far as we can."

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The system worked as it should have. A captain, two first officers and B.A. tech staff together concluded it was prudent to continue flying. To assume this team of professionals would willingly play fast and loose with the lives of 352 people, their own included, to save the cost and hassle of returning to Los Angeles is to misunderstand airline culture entirely.

Having said all that, my professional opinion is that the airline and its pilots indeed made the wrong decision -- just not a reckless or dangerous one. The 747 is built and certified for normal operation on four engines, not three. Had the surge taken place high over the Atlantic this wouldn't be worth debating, but that it occurred seconds after takeoff makes it another matter. Setting out for a nine-hour flight in this condition is not perilous in itself, but it potentially sets one down a path. Should another serious malfunction have taken place, unlikely as that would be, a semiroutine crossing would have become a full-blown emergency.

But my problem with the Journal isn't in reviving the kernel debate. My problem is with the paper's negligence at explaining the details of fuel planning, and perpetuating the notion of a daredevil crew -- caution thrown to the wind while a fuel gauge creeps toward empty.

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GO-AROUNDS

Re: Security outrage

"As a Brit living in the USA, I am amazed that people here passively accept this security nonsense: My 2-year-old daughter having to remove her shoes; my wife having to check her perfumes; a laptop having to be taken out of its case and put on a tray. In the U.K. most people are so conditioned by 50 years of brain-dead municipal socialism they'll accept any idiocy from the government. But I am astonished that Americans put up with this crap. Serve an American cold coffee or stale bread and he'll hit the roof. But have him prance around in his bare feet and tell him it's for security, and he's meek as a lamb."

Richard (last name withheld by request), Chicago

On that note, readers are encouraged to purchase fall's hottest new fashion accessory, designed and sold by "Ask the Pilot" reader Christian Campbell.

(Disclaimer: I receive no royalties from sales, though I was offered a complimentary shirt. Clearly there are two kinds of players in the security-industrial complex: those who rake in billions pretending to protect us and those, like myself and Campbell, who make a lot less complaining about it.)

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Do you have questions for Salon's aviation expert? Send them to AskThePilot and look for answers in a future column.


Patrick Smith

Patrick Smith is an airline pilot.

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