Misuse of Lightning Data RE: Air France 447

There was a lot of speculation going on yesterday, here and elsewhere, about whether or not there were thunderstorms around the Air France flight, and whether or not there was lightning nearby that could have hit the plane. This afternoon that is starting to become irrelevant as Fox News reports that messages from the plane indicated "it flew through towering thunderstorms" and "observed a strong and bright flash of white light that took a downward and vertical trajectory and vanished in six seconds" just before it crashed. Even if thunderstorms didn't cause the crash, clearly it was nearby. Below is an illustration of where the plane would have been flying into the storm.

But before that news broke, some sources were using lightning strike networks such as StarNet and/or WWLDN. You know I like to keep Media Accuracy in check, I have a whole category for it there to your right. I'm here to say today that some of these claims (saying there was no lightning) were irresponsible. Here's why.

In lightning detection, we look to "Detection Efficiency" - meaning what percentage of the lightning strikes are detected? This PDF shows that StarNet's D.E. For CG* strikes is less than 10% off the Brazil coast, meaning that over 90% of the lightning strikes go undetected (perhaps close to 100%). As such, you cannot show data from this source as evidence that there was no lightning because the data is incomplete. This is simple science and I'm disappointed to see major cable networks doing this.

*This assumes that the strike was a CG, Cloud-To-Ground strike; IC - Intra-cloud strike detection efficiency is even worse.

WWLLN's detection efficiency is stated to be 30% and they don't say whether or not that is CG or IC.

Are there more accurate networks for Brazil? Probably. I blogged last summer that Vaisala runs a short-range sensor network in Brazil. The more sensors you have in a particular area, the better your Detection Efficiency is. While StarNet has no sensors in South America, and WWLDN has one, which has been inoperative for the past week, Vaisala no doubt has a robust network in the nation. So far, however, they are keeping that data to themselves.