1 June 2009

Air France 447- Was it a Storm?

Posted by Dan Satterfield

The first thing I did when I got into work today was to grab a satellite image of the mid Atlantic around 3 am GMT. This is around the time that contact was lost with the Air France flight 447. The plane disappeared while crossing a band of thunderstorms that meteorologists call the ITCZ. That stands for Inter- tropical Convergence Zone. This is a semi permanent feature that tracks north and south with the seasons.

The ITCZ is what brings the rainy season to the tropics. Those who live in tropical areas break the year down into 2 seasons instead of 4. Wet and dry. When the ITCZ is nearby, you are in the wet season.

Now let me say off the top, I know little about the structural integrity of an Airbus. I have earned a pilot lic. and an instrument rating, but have never flown a jet. That said, planes are built to withstand much greater turbulence than the average person suspects. They are also built to take lightning strikes, and since they are not grounded, it is very rare for lightning to do significant damage. It has happened though.

Below is an image taken from 0245 GMT this morning. That’s 145am London time, and 945 PM Sunday night, Central U.S. Summer time. I drew a line of the approximate track the plane would have been flying.



This is an IR image. The clouds, land and sea are all showing up based on their temperature. The white pixels in the thunderstorm cluster along the track of the aircraft indicate temps colder than -50C. This means the storm tops were likely near or over 15,000 meters. Well above the altitude ceiling of an Airbus (or any passenger plane).

If the crash is weather related, my guess is turbulence rather than lightning. The one thing I noticed in the image is that the cluster of storms was several hundred miles wide and directly in the path of the aircraft. It would have meant a major delay in arrival time to go around the storms.

UPDATE 0215Z 1June:

Tim Vasquez is a meteorologist with extensive aviation weather experience in the Air Force. He has written a much more technical summary of conditions in the area. He mentioned the weather balloon sounding from an island near the last place that AF 447 was heard from. He makes a good point about the dry air aloft in the area. A bit atypical for a tropical sounding, and this could cause very strong downdrafts (due to strong evaporational cooling- cold heavy air sinks like a rock when surrounded by warmer air).


Tim comes to the same conclusion I did regarding turbulence being much more likely then lightning.

One of the scariest experiences I experienced flying involved a developing thunderstorm over North Carolina. I gave it a wide berth, but a sudden developing cell next to it caused a downdraft that dropped me 2,000 feet in a matter of seconds.