Ask the Pilot

The safe landing of the damaged Qantas 747 was no miracle. Plus: If a plane loses pressure, will your eyes pop out?

By Patrick Smith

Read more: Technology & Business, Australia, Airlines, Business, P. Smith, Ask the Pilot

Aug. 1, 2008 | Back on July 25, this column included a brief item about the safety record of Qantas, the kangaroo-tailed national airline of Australia. That same day, as fate would have it, a Qantas 747 en route from Hong Kong to Melbourne suffered an in-flight decompression, forcing the crew to make an emergency landing in the Philippines. A large hole was discovered in the forward lower fuselage, purportedly caused by a burst oxygen tank.

Although none of the 365 passengers or crew was injured, the incident made news all around the world, with photos of the "car-size hole" amply featured in full, above-the-fold color. Observers were incredulous. "How did the 747 remain in one piece?" Was it not a "miracle" that such a badly damaged aircraft managed to land safely?

In point of fact, no.

When it comes to aviation, media overreaction to minor events is nothing new. While not on a par with, say, the over-the-top coverage surrounding the emergency landing of a JetBlue Airbus three years ago, or the nonsense spawned by "citizen journalist" Jeremy Hermanns in December 2005, the Qantas mishap received its fair share of hype.

Let's begin with that "car-size hole" -- as several commentators put it. The area in question is just forward of the starboard wing, at the front end of a center fuselage fairing. The total area of damage may indeed be the size of a car, but much of it appears to be superficial -- the outer skin panels are torn away, revealing the structure and plumbing beneath. The actual puncture of the pressurized cabin, blown out by the oxygen bottle, is substantially smaller.

As most readers probably understand, airplanes are pressurized to compensate for thinner air at higher altitudes. Pressurization squeezes the air back together, increasing the amount of oxygen so that occupants can breathe normally. Introduce a large enough hole in that sealed vessel, and the pressure can no longer be maintained.

Decompressions can be mild or dangerous -- gradual, rapid or explosive -- depending on the size of the breach, the location at which it occurs, the speed at which it propagates and the level of pressurization (i.e., the airplane's altitude). Those caused by a bomb, for example, run a high risk of destroying the plane, as seen in the terrorist attacks against Pan Am 103 and many others. The initial blast may be small, but resultant forces can rip the plane to pieces in a matter of a few seconds. Damage to crucial systems is another factor. Debris can be flung into engines or smashed against control surfaces. In 1974, the blowout of a lower-deck cargo door on board a Turkish Airlines DC-10 caused the cabin floor to collapse, severing control cables and rendering the plane unflyable. (It went down near Paris, killing 346 people -- the fourth-deadliest accident in aviation history.)

But those are worst-case scenarios. Not even a bomb or other major failures will necessarily result in a crash. Consider the TWA 727 that withstood an onboard explosion in 1986, or the United jumbo jet that survived loss of a cargo door and a large section of fuselage after takeoff from Honolulu in 1989. Several passengers were killed, but hundreds survived. Or, in the most incredible example of all, who can forget Aloha Airlines Flight 243, the Boeing 737 that lost an entire section of its cabin -- ceiling, sidewalls and all, right down to the floor -- yet managed to land safely, with the death of only one person.

Any fuselage rupture is serious. But serious does not mean imminent disaster. The Qantas jet remained structurally intact, while its crucial systems and flight controls were not adversely affected. This was hardly the near catastrophe implied by much of the coverage.

The crew members faced a rapid decompression, to which they responded, as would be expected, by initiating an emergency descent. This is standard procedure following any uncontained loss of cabin pressure. The pilots first don their oxygen masks, then run through a series of five or six steps to establish a rapid descent. The plane will lose altitude at several thousand feet per minute. The idea is to reach a safely breathable level -- 10,000 feet, typically -- as quickly as possible. Troubleshooting begins after you get there. Oxygen masks in the cabin will have deployed automatically -- or, if need be, the crew will release them with a switch.

Next page: A pilot is likely to spend an entire career without ever seeing a real emergency descent