Was Air France flight brought down by turbulence or hail?
100 m.p.h. winds, hail, and rain might have brought Flight 447 down, says a former Air Force meteorologist.
By David Clark Scott | 06.02.09
Was Air France flight 447 brought down by a 100 m.p.h. updraft?
Or were its two jet engines snuffed out by hail or heavy rains?
In the absence of a black box, the leading theory now is that the Airbus 330-200 was brought down by a 300-mile-wide band of tropical thunderstorms that it could fly neither around nor over.
Brazil’s defense minister confirmed Tuesday afternoon that military planes found a three-mile path of wreckage in the Atlantic, hundreds of miles from Fernando de Noronha, a Brazilian archipelago.
Professional pilots and meteorologists are digging through the available data – flight routes, satellite images, aircraft specifications, and weather reports – and spinning out several likely causes.
One of the most detailed and cogent pieces of analysis of Flight 447’s last minutes – winning the praise of pilots around the world – is a blog by Tim Vasquez.
Mr. Vasquez is a former US Air Force meteorologist. He now consults and publishes weather forecasting texts and software.
Vasquez plots the likely flight path of Air France 447 and overlays it on satellite imagery and weather reports in the area at the time:
It appears AF447 crossed through three key thunderstorm clusters: a small one around 0151Z, a new rapidly growing one at about 0159Z, and finally a large multicell convective system (MCS) around 0205-0216Z. Temperature trends suggested that the entire system was at peak intensity …
Air France says that it received an automated message from Flight 447 reporting electrical faults and loss of pressurization. Vasquez says that message was sent just as the jet was nearing the final edge of the storm cells, but after being battered by turbulent updrafts as high as 100 mph for about 12 minutes (or 75 miles).
Several pilots, in comments on his site, agree that turbulence was probably a factor.
AccuWeather.com, a private forecasting firm, issued a statement Tuesday, offering a similar theory based on its own data:
The plane appears to have flown into or near a large cluster thunderstorms that were in the development stages northeast of Fernando De Noronha, which is located off Brazil’s northern coast, and along the Intertropical Convergence Zone (ITCZ), the belt of low pressure that surrounds the Earth at the equator.
Based on weather information from Fernando De Noronha, the updrafts associated with the thunderstorms may have reached up to 100 m.p.h. Such an updraft would lead to severe turbulence for any aircraft. In addition, the storms were towering up to 50,000 feet and would have been producing lightning.
At its last check-in time, the Air France aircraft was flying at 35,000 feet. A check of the Airbus 330-200 specifications shows that the aircraft has a ceiling of 41,000 feet.
It couldn’t fly above a thunderstorm with a 50,000-ft. top. It would have been using its onboard radar to try to pick a path through the storm cells.
Vasquez also makes note of another possible cause: The jet engines were shutdown by rain or hail.
A dual engine flameout due to precipitation or ice ingestion is a noteworthy possibility as has been discussed on other sites
(specific to the A330 type too). The precipitable water content in any tropical weather system can run very high.
Vazquez says that lightning may also have been a factor. And Accuweather raises the same point:
Tropical thunderstorms and the lightning patterns generated by them are different from storms that typically occur over the United States. Studies have shown that the top region of tropical thunderstorms is highly charged and more conducive to lightning, which indicates that an airplane flying near the top of a tropical thunderstorm could be more susceptible to a lightning strike. Tropical thunderstorms are also notorious for producing frequent cloud-to-cloud, as well as cloud-to-air lightning.
But commercial pilots and aviation safety experts say that such jets are designed to take lightning strikes without significant damage. Still, the fact that this was a fly-by-wire aircraft (where the control surfaces are moved by electrically signaled controls, rather than cables, chains, and pulleys) raises doubts among some pilots.
Most pilots, in the absence of more information, are leaning toward turbulence or engine flameout as the most likely causes of AF447’s demise.
But there is at least one faction within the meterological community that disagrees with the theory that the Air France jet was brought down by a storm.
The World Meteorological Organisation (WMO) says that two Lufthansa jets – heading from South America to Europe – flew through the same area where the thunderstorms were reported, about half an hour before the AF447.
The two aircraft collected wind and temperature information during their flight as part of a WMO program.
On Monday, a source with access to the data transmitted to WMO told Reuters in Paris that the two jets passed through turbulence before and after the plane without incident….
More than 5,000 aircraft collect data under WMO’s Aircraft Meteorological Data Relay Programme (AMDAR). The two Lufthansa jets participated in the system, but not the Air France flight, according to the Geneva-based United Nations agency.
But Herbert Puempel, chief of the WMO’s aeronautical meteorology division, also told Reuters that thunderstorms tend to be very localized. If one plane reports turbulence, another one passing through the same area even shortly afterward is unlikely to experience it.
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2. Juliana | 06.02.09
As a person that flights often and has little information available on safety on planes (as millions of people around the world are), I’m trying to make the information meet.
I guess the questions that everyone would make are:
1. Would being part of the WMO programme have prevented the Air France flight to meet with such harsh weather?
2. Why wasn’t Air France part of that programme?
3. So far, all experts have been particularly specific that WEATHER ALONE WOULD NOT HAVE BEEN ENOUGH TO MAKE THE ACCIDENT HAPPEN. In other words, something else, a concurring factor, MUST HAVE HAPPENED. If so, what possibilities are for such a factor? Human and mechanical (or, in this case, electrical, since the 330 airbus is 100% electric), correct?
3. Richard Sisk | 06.02.09
Clearly, all automated messages from commercial airliners should contain GPS coordinates allowing for more precise positioning of rescue search aircraft.
4. David K. McClurkin | 06.02.09
This is an extraordinary piece of reporting on an emerging story. Well done!
The links are awesome, particularly that from Mr. Vazquez. Congratulations on presenting this information in highly readable form, with the drill-downs for those more technically inclined.
5. Craig | 06.02.09
With only 228 people on board, could the aircraft have been too light to be going through that kind of turbulence. Heavy planes tolerate radical movements better.
6. Mr Pepper | 06.03.09
Air France Flight 447 was in the wrong place at the wrong time. This sad fact - the simplest explanation - is the most plausible. This demonstrates the unpredictabiliyt of sudden busts of violent weather formations, and shows that if global warming is correct, then we can expect more of this around the word.
Perhaps we need airplanes that jump into orbit and so avoid the atmosphere altogether, expect from take-off and landing.
7. Bill | 06.03.09
Hello,
Although extremely unlikely, but since this was a catastrophic event on a strong plane and there is no evidence of what really happened, I wonder if there was a meteor strike on the plane?
Regards, Bill
8. Brother Al 73 | 06.03.09
My understanding, based on reporting since the Air France plane disappeared, is that a band of thunderstorms is a normal occurence in this area near the equator. I’m not a pilot or aviation expert, but if that is the case, why do airlines continue to route aircraft through the area?
9. Art R | 06.03.09
What caused the concurrent loss of air pressure and electrical failure. Was the pressure loss due to an explosion?
10. Asim MA san antonio,tx | 06.03.09
Still, it is mind boggling as to why did the Captain take the aircarft into the storm in the first place-which should have been known to him from his pre-flt Wx briefing??
Once recovered, a very instructive and invaluable lesson should be learnd from the black box by the entire aviation community:airlines and aircraft manufacturers to protect passenegr safety in the future.
11. Gerald | 06.03.09
Air Transport Aircraft are designed to withstand forces equal to about 4.5G (gravity) positive and about half of that in the negative without the wings falling off when the airplane if at gross load (fully loaded). Being not fully loaded does lessen the wing loading and allows the aircraft to exceed these design limits before the wings are supposed to fall off. Passing through a severe thunderstorm with high velocity vertical winds in both up and down directions is dangerous. Old pilots have told me that “There is a 6G differential in big storms somewhere”, and that I should not fly into any large storm.
Fly by wire is not a new technology. The F-16 has had “fly by wire” since it was developed in the 1970’s, or was it the the late 1960’s, but the passengers had ejection seats that were used when “fly by wire” or other flight systems failed. The F-16 had several redundant electrical systems.
An Airbus A330 flew into the trees at some European air show years ago, and they final report blamed the “fly by wire” system.
Maybe some cable system to control flight surfaces when there was an electrical failure would at least give the pilot and passengers a chance.
12. Matt Rhead | 06.03.09
Based on Mr. Vasquez’s superb analysis, it appears that the multiple storm cells would have been too large to deviate around, and the A330 is not rated to fly at FL510. Thus, the crew would have had no choice but tho try to “thread the needle” and work their way through the system. The A330 has had several incidents of the onboard computer system putting the aircraft into an unplanned dive (Qantas flight from Singapore to Perth). Could it be possible that the intense turbulence and/or a lightning strike disrupted the computer system, resulting in an unplanned dive through a severe storm system, from which the crew was unable to regain control?
13. johnnyredneck | 06.03.09
Im a mechanic for over 20 years , a thunder storm will bring down the largest jets made
14. Wright Gifford | 06.03.09
It does seem strange that in this very sophisticated world that a plane as advanced as this one was that it did not have GPS capability and send its position when it automatically sent the fact that it had electrical problems and had lost pressure.
15. Richard A | 06.03.09
Is it possible that lightning or severe turbulence blew out a window in the pane causing rapid depressurization? Could that explain the lack of messages from the crew, and breakup of the plane?
16. Thomas Shafovaloff | 06.03.09
Downdrafts and updrafts within a cumulonimbus along with turbulence, large,supercooled freezing water droplets and lightening are startling evidence of a poor decision to fly through them. The less obvious danger is hail that can occur within 10’s of miles of a cumulonimbus. If the pilots had any military flight training they most likely had been given a brief demonstration to make them beleivers in flying safe when in the vicinity of that kind of weather. [Not the hail but actually experiencing the weather inside a cumulonimbus. There are enough photos of bent aluminum and accident reports demonstrating results of hail damage.] These were experienced pilots. Hopefully quite an effort will be put into locating the black boxes. I wonder what the telemetry on engine operation looks like. And, the statisticians should be hard at work predicting the location of the black boxes. The same data was not available at the time of the Titanic, remember the sunk submarien that was located off the Eastern US years ago? “Statisticians.”
Also, though I am not certain about paramaters, the engines probably can be subject to so much turbulence before the fan blades strike what surrounds them and that would be catastrophic in and of itself.
17. flyboy | 06.03.09
The swathe of debris suggests mid air explosion to some of us. I think that for international safety it would be in all our interests if the flight recorders were recovered even if foreign subs had to be involved. I remember when two engine planes over the atlantic was “never going to happen”. Technology has moved on but then again wihout the black bo recorders we cannot be too sure of that.
18. carolinec | 06.03.09
Caroline, NYC
As a white knuckle flier, why do the airlines allow pilots to fly through such storms that are known to be in the area and too high to fly above? Why don’t they re-route the flight or delay it until it is safe to fly? Obviously this is an area known for violent storms that can go up to 50,000 feet. Why do the airlines even fly this route? Also, why isn’t there better radar on board these “state of the art” , “fly by wire” planes? Finally, why doesn’t the technology exist to have all cockpit conversation/sounds/noise be relayed to airline HQ in real time? Like a wiretap device, or just keep the voice radio button “on” the entire flight so there is a recording of the cockpit always taped on land? Why do we always have to rely on these black box’s when there could just be a virtual recording available…
19. Edward Quirk | 06.03.09
FLY BY WIRE
INTERESTING!!!
Actually the pilot does NOT fly this plane - he only makes suggestions to the computer which is actually flying the plane.
Remember HAL
20. Graeme Barlow | 06.04.09
If the engines had been knocked out by hail surely there would have been a mayday call from the flight deck. Is it possible that large enough hailstones could have shattered the windshield and killed the pilots, also resulting in sudden decompression?
21. Suresh Kurapati | 06.04.09
My first question to Air France officials is - Why was the flight allowed to take off inspote of bad weather in that region ?
22. steamtrn | 06.04.09
The history of modern aircraft downed by turbulance alone is sparse. In the past some accidents have been attributed but not proved to be victims of “rogue” winds (Colorado Springs UAL). We can only speculate what actually happened, until further evidence is recovered.
24. Em | 06.04.09
Couldn’t understand half of Vasquez’s report, but weather analysis has never been so interesting…
25. artistkvip | 06.08.09
updrafts in thunderstorms produce hail… 100 mph updrafts would produce very very large hail. why is hail breaking the windshields or the thin alumanum skin or blasting the radar out of the nosecone as well as clogging the the windspeed tubes not being talked about. is it a pilot error legal responsibility thing. why not report all the science and probabilities mnot to mention actually history of hail severely damaging and crashing very large planes
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1. neil borodkin | 06.02.09
I have not read anywhere in the news about why this flight did not re-route given the advanced nature of weather radars these days. Surely this very intense storm system had been detected.