LISBON - The Fairey single engine float plane is displayed as if taking off over the Tejo River. But when Gago Coutinho and Sacadura Cabral departed Lisbon in the first crossing of the South Atlantic by air in 1922 they were not flying in this particular airplane. Their historic feat was only accomplished in a three airplane relay, the first two planes were lost along the way. But in such perseverance is aviation history (and aviation safety) made.

This was made clear to me again on Sunday. As I was learning about these Portuguese aviation pioneers and their ultimately successful travails in flying from Portugal to Brazil, air crash investigators with the French Bureau d'Enquetes et d'Analyses or BEA were rewarded by their own travails in the South Atlantic with the discovery of wreckage from the Airbus A330 that flew as Air France Flight 447. The so-far mysterious crash of Flight 447 from Rio de Janeiro to Paris nearly two years ago, has been as loaded with drama as it has been light on details.

Remember the plane carrying 228 people was at cruise altitude when, after a few minutes of automated maintenance warnings to Air France through the ACARS system, the plane disappeared. Since then, the only operating theory is that ice in the speed-measuring pitot tubes caused incorrect readings by the autopilot leading to the crash. All Thales pilot tubes were ordered replaced by aviation authorities.

Despite the fact that no one yet knows what happened to Flight 447, the French government recently filed manslaughter charges against Airbus and Air France. You read that correctly. This is not an unprecedented step for the French. Continental Airlines and an employee were found guilty of manslaughter in France just three months ago for the crash in Paris of the supersonic Concorde in 2000 that killed 113 people. (That ruling that got remarkably little attention, frankly. Continental says it will appeal.)

Anne Candies during the April 2010 search

It is quite obvious that everyone wants to know more about what happened to Flight 447, making the $40 million plus cost of the repeated underwater searches bearable - in spite of the continual raising and dashing of hopes from the previous fruitless searches.

The Portuguese naval aviation pioneers Coutinho and Sacadura left Lisbon in March 1922 on a three-month effort to fly to Rio de Janeiro using a sextant they designed for air navigation. The journey required multiple stops for fuel along the way and cost three airplanes. 

During one sea landing gone awry, the pilots found themselves in the water holding on for dear life to the floats of their sinking aircraft. Undoubtedly they must have had their doubts. But through the efforts of many people, the aviators were rescued and they prevailed. They entered the history books yes, but just as important, they left a legacy of determination entirely relevant today.

Yes, I'm trying to take a few days off for fun before the beginning of the European Society of Air Safety Investigators conference in Lisbon, but what could I do when I saw the news story? Another aging Southwest Airlines 737 pops a hole while at cruise altitude? A skylight in an airliner is bad enough the first time.

Friday evening, while at 36,000 feet, Southwest Flight 816 from Phoenix to Arizona developed a suitcase-sized tear in the upper fuselage about 45-minutes after takeoff. The hole was big enough to bring the cabin altitude, normally maintained by the pressurization system to around 8,000 feet, to above 10,000 feet in 45 seconds. This causes the passenger oxygen masks to drop. But even when passengers quickly don them, it can also cause a lot of discomfort. (Read more than you'll ever want to know about depressurization events on 737s here.) 

A passenger and a flight attendant lost consciousness. In the meantime, the pilots began a twice as fast as normal descent (4,000 feet per minute) to get the plane down to 11,000 feet before heading for a military base in Yuma, Arizona where they made an emergency landing.

This event is especially creepy because less than two years ago, I reported on a similar scenario on another Southwest 737-300. B.N. Sullivan's blog Aircrew Buzz has a fairly detailed explanation of what NTSB investigation revealed which you can read here.

As might be inspected when your airline is hit with this kind of can-we-say-nightmarish-publicity, the COO of Southwest is eager to suggest that this second fuselage-ripping event is in no part due to any lapse or action of the airline. Nope, Mike Van de Ven says Friday's episode is baffling even Boeing.  

Mike Van de Ven Southwest Airlines photo

In a statement, Van de Ven says, Boeing has identified an inspection program and "based on this incident and the additional findings, we expect further action from Boeing and the FAA for operators of the 737-300 fleet worldwide.” Well Southwest doesn't fly outside of the U.S. yet, so that "worldwide" is supposed to lead us to conclude the problem is bigger than Southwest. Well maybe it is.

But really, how do you say this with a straight face? "What we saw with Flight 812 was a new and unknown issue." Say what?  The effects of age on aircraft structure burst onto the scene quite literally twenty-three years ago when Aloha Airlines Flight 243 lost 18 feet of fuselage during a passenger carrying flight. This dramatic event, in which a flight attendant was killed after being sucked out of the airplane, launched the air safety regulators on long-running and multi-faceted investigations into operation, maintenance and inspection of airliners as they age.  For five years, I participated on the FAA's follow-on committee which expanded on structures to include the effects of age on aircraft systems. But I digress. 

The fact is that while many airlines have been replacing older model airplanes, they still represent a sizeable portion of the all-737 Southwest fleet. And, if you're looking for an airpline that rides them hard, you need look no farther than Southwest. Short haul flights and extra fast turn around times at the gate mean, according to Patrick Smith of Ask The Pilot fame, that Southwest Airlines has one of the highest airplane utilization rates in the industry.   

As of day two of the grounding of 300 Southwest 737s the airline has found "small, subsurface cracks" on two of twenty-one planes using a testing procedure not previously used on airplanes for this kind of detection, as far as I can tell.  That may be the "unique" referred to by the Southwest boss.  

If high frequency eddy current testing can detect invisible cracks that will be another positive development in the ongoing effort to maintain the integrity of older airplanes. But Southwest and other airlines with demanding operations would do well not to forget that aging fleets require special care and there's nothing "new and unknown" about that.