Wednesday, June 3, 2009

Man vs nature, Air France flight 447 crash

Man vs nature - guess who loses

If there is anything the crash of flight AF447 in the Atlantic proves, it is that even man’s most advanced technology can be overwhelmed by the forces of nature. The Airbus A330 involved was one of the most modern and advanced airliners ever built, with an exemplary safety record. But even that plane was not able to climb high enough into the stratosphere to stay above the thunderstorms of the tropical ‘Black Hole’ where airflows from the northern and southern hemispheres encounter each other. It now seems likely that it could not handle the combination of heavy icing, hail, excessively powerful turbulence and possibly lightning strikes, in whatever order or simultaneously.

This accident also demonstrates the arrogance of man, and what happens if economic considerations and the ‘need’ for speed outweigh safety concerns.
The shortest route between Paris (Europe, basically) and Rio passes right through the ‘Black Hole’, where planes frequently encounter severe thunderstorms. Using their weather radar, the pilots can anticipate those encounters and change course to avoid the most powerful cumulonimbus ‘towers’, where turbulence may be powerful enough to literally rip even a large airliner apart, and where hailstones the size of eggs smash into the cockpit windscreen. But as most people involved in aeronautical weather forecasting know, thunderstorms can rapidly grow ‘children’, and once a plane finds itself surrounded by fast-growing CB towers, it may be trapped. The thunderstorm area encountered by AF447 was particularly large, and the question rises whether its existence, or development, was not known by the time of take-off about six hours earlier, and if it would not have been possible to divert the flight either to the US or along a trajectory south of the storm area, crossing the ocean straight eastward to Africa. In both cases, very likely an intermediate landing would have been needed, or a lot more fuel carried. Of course, the company could even have decided to cancel the flight, or to wait for better weather - which apparently is almost impossible on that route, as the weather is always bad.
So the question rises: do airlines deliberately send planes into known areas with frequent severe weather for economic reasons? Because it shortens the trip and thus saves fuel? Because it enables them to offer a faster direct flight to faraway destinations, and thus to sell more tickets compared to companies who only offer indirect connections?
The answer is probably ‘yes, they do’.
In this particular case there is another disconcerting possibility: that the pilots were forced to cut it a bit too close. Air France/KLM at the time was suffering from extremely high fuel costs compared to other companies - the result of a long-time fuel contract they had signed with their suppliers in late 2008. They thought that fixing the price for kerosene at 80 dollars per barrel was advantageous at the time, but the oil prices kept on collapsing and other companies managed to sign contracts for prices between 60 end 70 dollars per barrel... Did this perhaps cause the company to prohibit the crews from taking on ‘too much’ spare fuel, thus making it impossible for them to take a long trajectory around the thunderstorm area - instead forcing them to cross through the area and zig-zag between the worst cumulonimbus cells? Did they finally get trapped as a result of that?
The long-haul flight Paris-Rio is about 9200 kilometres in a straight line (‘great circle’ distance). The A330-203, the type used for flight AF447, has a maximum range of 12.500 kilometres (likely less with headwind, more with tailwind). Thus with a full fuel load, it could have flown at least 2000 kms around the storms and still kept a 1000-km safety margin. So why did it not take that long way around? Why did it not traverse the Atlantic a safe 500 kilometers or so southward, towards Africa, and then skirted the African coastline towards Europe? It had the range to do that, if it was fully fueled up. Sure, it would have landed one or two hours later, but those 226 people on board would still have been alive.

Being a pilot myself - of hot-air balloons, but still - I can certainly imagine that no captain, no pilot of even the strongest, most powerful plane ever built is happy to fly through a severe-weather area like the ‘black hole’. Given the choice, they would likely prefer to take the long way around. But it seems they are not given that choice by their employers.

And this time, Nature did not play along with the bean counters.

Soft landings.

1 comment:

  1. Added on 10/06/2009:
    Now it turns out that a Lufthansa plane suffered an 'incident' in heavy turbulence over the same area, a few days earlier. If the investigators and aitlines may be believed there was nothing unusual about the weather conditions that destroyed the Airbus. Faulty speed indicator pitots may have been a possible cause. And more than 40 bodies have been found.
    Nothing unusual. Think about it when you board a plane.