Air France Jet Crash

  1. You have probally all heard about the Air France jet crashing in the Alantic.

    Reports so far have suggested that lighting was the cause of failure.

    Now I believe Commericial Air Crafts are struck by lightning at least once a year. Lightning is suppose to pass around the exterior of the plane causing only small distrubance.

    From what I have read though lightning strikes can cause structural damage and electro-magnetic interference.

    So the question is how safe are commercial jets against lighting strikes ?

    How accurate are our models for predicting damage on a plane from lighting strikes ?
     
  2. jcsd
  3. russ_watters

    Staff: Mentor

    Re: Air Fran Jet Crash

    Welcome to PF!

    I was wondering when someone would post about this incident and I'm glad you did it in engineering instead of general discussion!
    Correct, and since the initial reports, most news sources I've seen have backed off that speculation, noting that airplanes are designed to withstand lightning.
    The easy answer is that they are very safe, but nothing can be completely safe. More specific, I can't be because I don't have a lot of specific knowledge of the testing and modeling of this. We have plenty of members with more specific knowledge of this subject than me, though, who I'm sure will weigh in...
     
  4. Thanks for the response.

    I just read that "The head of communication at Air France said the plane, an Airbus A330, had probably been struck by lightning" so i'm not too sure what the deal is.

    If it had been struck by lightning I wonder how it damaged the plane?

    If the report was false then I guess it could be almost anything. Have to wait until the black box is found.
     
  5. FredGarvin

    FredGarvin 5,087
    Science Advisor

    A lot of work and certification testing goes into an aircraft and its engines. A proper ground path between major components is a mandatory design feature. We just finished lightning strike testing on one of our engines.

    That being said, there is no way to ever predict the worst case scenario when it comes to mother nature.

    Personally, I don't buy the lightning strike theory. It may have had a contributing factor, but I doubt it was the main factor. Unfortunately, it looks like we may never know.
     
  6. Astronuc

    Staff: Mentor

    Here is some information on the research of lightning and aircraft interaction.

    http://www.sae.org/aeromag/features/aircraftlightning/

    http://oea.larc.nasa.gov/PAIS/Concept2Reality/lightning.html
    I've seen a video of some of these experiments, but I can't find it on the internet.


    Lightning might have been a factor. There is some speculation that aircraft with composite material might be more vulnerable to lightning strikes - but as of now, that's speculation.


    Commercial aircraft have lightning wicks (basically lightning rods) or protusions with which to facilitate the conduction current in a more controlled process.

    Lightning Strikes Airplane [Boeing 747] During Takeoff



    As Fred mentioned, it will be difficult to find in the mid Atlantic. The craft seems to have gone missing somewhere near the mid-Atlantic Ridge.
    http://news.yahoo.com/s/ap/brazil_plane
     
    Last edited by a moderator: Sep 25, 2014
  7. Borek

    Staff: Mentor

    So far they have not even approximately located the plane.

    Anybody knows what is a range of underwater locator beacons?

    Obviously the range will depend on the equipment used for detection so there can be no easy answer to that...
     
  8. Astronuc

    Staff: Mentor

    Update: Some possible aircraft debris found along path of AF447.

    http://news.yahoo.com/s/ap/20090602/ap_on_re_la_am_ca/brazil_plane
     
  9. DaveC426913

    DaveC426913 16,081
    Gold Member

    Did I not hear in the report that the plane sent out a warning complaint of electrical problems shortly prior to radio silence? Presumably the lightning fried some critical navigation or flight component(s).
     
  10. Thanks for the information. A very good read.
     
    Last edited by a moderator: Sep 25, 2014
  11. russ_watters

    Staff: Mentor

    It also reported a cabin pressure loss, so I was thinking about it from the other direction: that wind shear had caused a structural failure, leading to both the cabin pressure loss and electrical failures. But I haven't seen it reported what order the failures were reported in.

    My gut reaction to the early news reports was to think about the last time this many people died in a plane crash: in 2001, when wake turbulence and possible pilot or computer overcorrection tore the tail off an A300 over New York. http://en.wikipedia.org/wiki/American_Airlines_Flight_587

    We certainly can't rule out lightning completely, but it would be an exceedingly rare failure. Lightning hasn't taken down a commercial airliner in more thana 40 years and an average, every airliner is hit by lightning once a year, so there have been millions of lightning strikes since then.
     
  12. DaveC426913

    DaveC426913 16,081
    Gold Member

    IIRC, often air accidents are a conflagration of events. Lightning in conjunction with some other element(s), such as the age of the plane may be the cause. I heard early reports mentioning how old the plane was, though I think they said it was only 4 years or something.
     
  13. I don't suggest this as the most plausible, or even likely cause, but not beyond some consideration. It's not unheard of that ball lightning can enter an aircraft.

    http://www.straightdope.com/columns/read/2562/does-ball-lightning-really-exist

     
  14. Here is a weather analysis in the vicinity of AF447.

    http://www.weathergraphics.com/tim/af447/

    Wikipedia has the most comprehensive ACARS (Aircraft Communications Addressing and Reporting System) transission sequence I've seen so far. ACARS is the autonomous data broadcaste system the A330 utilized to report fault conditions directly prior to it's demise. It's about four screens down under "Incident".
     
  15. Borek

    Staff: Mentor

    Can't find it - can you please give more detailed pointers?
     
  16. Borg

    Borg 1,099
    Gold Member

  17. LURCH

    LURCH 2,512
    Science Advisor

    Could have been positive lightning (BIG maybe).
     
  18. it was shown on the news that half an hour after last contact, weather satellites recorded extreme weather near where the plane was. could bad weather have crippled the plane.

    also just as a guess. could the plane have suffered engine failure while in the storm. after all, there were electrical problems and i think the engines provide some power and also the engines i believe maintained presurisation and it is thought that there was a cabin loss of pressure
     
  19. Borek

    Staff: Mentor

    Pure speculation if you ask me.
     
  20. Mech_Engineer

    Mech_Engineer 2,299
    Science Advisor
    Gold Member

    Whatever happened to the plane, it had to have been so chatastrophic that all communications and flight controls failed such that the pilots could not control the plane AND could not radio out a mayday. Possibly massive wind shear causing the airframe to break apart, but it seems to me that lightning is unlikely due to the number of double and triple redundant systems governing critical systems such as flight controls.
     
  21. mgb_phys

    mgb_phys 8,952
    Science Advisor
    Homework Helper

    The engines normally provide all the electrical power, there is an emergency wind powered generator that deploys automatically if they fail. Losing both engines in cruise isn't a disaster - a 747 glided for 15minutes after losing all 4 engines when flying through a dust storm. Another A330 that ran out of fuel flew for 20 minutes before landing in the Azores.
    The engines are used to pressurize the cabin and provide the heating and AC but the air doesn't suddenly rush out if they stop.

    The sequence of events and debris look like it broke up at altitude but it's going to take the recovery of more evidence to work out why.
     
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