Thread: Air France Incident!!!

It has been suggested that the plane may have been hit by lightning, how does this happen? Lightning being static electricity, wants to find the path of least resistance to ground, a plane mid flight is not earthed. Is it that the metal offers lower resistance than air/water? Do planes have lightning arrestors?

What amazes me is how the plane crash investigtors can pin point the cause of an accident.

Planes are at a different "potential" so can attract lightening. Lightening strikes not uncommon...there are usually special conductors on the trailing edge of the wing, rudder and (rear) elevators to mitigate its effects. A decent strike however with perhaps a million volts on what is a massive conductor can cause havoc to the multitude of ECUs, activators etc (think effects of voltage spikes from electric welding the chassis of a P38/D3 etc without taking precautions...) that's why they try to fly above the weather...or go around it... 5 hrs into a flight one would have thought they were at about 35-40,000 feet...must have been a hell of a storm..I've witnessed a 50' eucalypt shredded by a decent lightening bolt...my ears were ringing for a couple of days after...can you image it hammering an aluminium can just a few mm thick!

Originally Posted by crash

What amazes me is how the plane crash investigtors can pin point the cause of an accident.

In their opinion, with no survivours to refute the guesswork.

Lightning strikes on aircraft are quite common, and almost always harmless to metal aircraft. Because there is no way the aircraft while airborne can have different parts of it at significantly different potentials, the current flow is quite low. The high frequency nature of the discharge means almost all the current remains on the outside of the aircraft. The A330, because of its "fly by wire" control was extensively tested in lightning, and it is worth noting that since it has been in service for about ten years, there would have been numerous lightning strikes on it. This is the first hull loss of any A330 in service (one crashed during testing, supposedly due to pilot error).

For what it is worth, my guess is that it flew into very severe turbulence in the intertropical convergence zone, and suffered structural failure, and midair breakup when loading on the wings or control surfaces greatly exceeded design loads. This is consistent with the report of it sending automatic system error messages.

If the flight data recorders can be found (and they have sonar transponders to help find them in water) the data would probably tell exactly what happened. The problem is that it was out of radar range, and may have deviated from its planned course to avoid storm sells, possibly by hundreds of kilometres.

John

Originally Posted by V8Ian

It has been suggested that the plane may have been hit by lightning, how does this happen? Lightning being static electricity, wants to find the path of least resistance to ground, a plane mid flight is not earthed. Is it that the metal offers lower resistance than air/water? Do planes have lightning arrestors?

I was on a flight from Perth - Brisbane that was struck by lightning. As JD said, it is quite common, and usually no big deal.

We were reducing altitude in preparation for our approach to brisbane airport when it happened, I think we were coming down through a thunderstorm. There was a slight flash outside coinciding with an EXTREMELY loud bang, and the cabin filled with an ozone-smell. Surprisingly, most of the passengers remained quite calm. The pilots and stewards didn't make any announcements, but we all realised what had happened.
After we had landed and were taxiing in, the pilot said "In case you were wondering, we WERE struck by lightning back there. Sorry we didn't make an announcement at the time, but were were quite busy in the cockpit" (I'm sure they were checking all the systems were still operational!!!). I have been told that planes must be grounded for mandatory checks after lightning strikes..

what ever happen it would have been terrible for those people aNd now the people they left behind. My thoughts and condolences are with them.
geck

Originally Posted by JDNSW

For what it is worth, my guess is that it flew into very severe turbulence in the intertropical convergence zone, and suffered structural failure, and midair breakup when loading on the wings or control surfaces greatly exceeded design loads. This is consistent with the report of it sending automatic system error messages.

Yes, it seems more likely that turbulence has caused structural failure of the aircraft. Wind shear is a well known cause of catastrophic damage to aircraft.

We all feel for the people killed, and the families left behind.

Cheers,

Lionel