Lightning hits two Qantas jets

[Wirraway]

ABC News Online
Sunday, November 7, 2004. 6:12pm (AEDT)

Lightning hits two Qantas jets

Two Qantas jets on their way from Brisbane to Melbourne have been struck by lightning just after take-off.

The first plane was struck around 11am AEST, with the second hit about one hour later.

Both aircraft completed their flights to the Victorian capital.

A spokeswoman for Qantas says one of the planes has been cleared to fly and the other is still being examined by engineers.

She says there were no injuries.

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[Capt Fathom]

Must be a quiet news day?

[Aussie]

Can anyone explain what happens to aircraft after a lightning strike?
DOes the electricity dissipate?

Can it cause the malfnction of electrical equipment?
Cheers

Aussie

[Kiwiconehead]

Can anyone explain what happens to aircraft after a lightning strike?
DOes the electricity dissipate?

The lightning passes thru the aircraft so there isn't really any electricity to dissipate afterwards - like sticking a spanner across the terminals of a car battery, it may be red hot and melted but there isn't any electricity eft in it.

There are usually entry and exit points from the lightning, trailing edges/static wicks are usually good exit oints as the aircraft moves thru the bolt.

Can cause major damage to components. ranging from tripping generators offline to frying radio components, ADFs seem to be particularly susceptible.

Have seen a #2 VHF antenna blown off a 146 by lightning - missed it on my first walkaround as there were only 4 bent studs and a black charr mark left on the airframe.

[Cornholio]

Another blunder by the rat. You don't need much more of a warning but they dispatched another flight, anyway, straight into the fray and took the hit. What a surprise.

See that big black thing over the field? It's called a "THUN-DER-STORM". It contains something known as "LIGHT-NIIIING".

I wonder how the fare-paying passengers felt about these guys taking off straight after a previous jet had been struck..... :rolleyes:

:confused:

:hmm:

:zzz:

[FishHead]

Kiwiconehead - actually, the elec discharge is meant to travel 'around' the aircraft rather than 'through' it. That is to say, a Faraday Cage effect. You dont travel through the bolt either - it is more a case of it reaching out to touch you to ground itself.

As far as Cornholio goes, I gather that most people are not responding to his posts? Certainly shows a lack of knowledge of flying around lightning, and the random way it can behave. Still, best to not bite...

[invertedlandings]

Woomera...ban Cornholio now



I prefer he suffers for awhile first! :E

Woomera

[stickwithit]

Cornholio said...
"I wonder how the fare-paying passengers felt about these guys taking off straight after a previous jet had been struck..... "

Must have been one of those weird TSs that sits off the runway for an hour (not straight after??). You must know, you even knew how black it was... Get out of the training area much Cornholio?? ;)

[DutchRoll]

I guess Cornholio doesn't generally know all that much about aeroplanes or weather by the sound of it.

Aussie, the key to it all is the fact that electricity likes to travel through the best conductor it can find at the time. The metal skin of an aeroplane just so happens to be a very good conductor and the charge is mostly dissipated through this. As Kiwi alluded to, the static wicks along the wing & tail, where the energy is most likely to exit, assist greatly in discharging the energy.

There need not actually be observed lightning strikes in a particular cloud for an aircraft to be struck by it, nor even any actual thunderstorm activity. 90% of aircraft lightning strikes are triggered by the entry of the aircraft into an intense electrostatic field, the remaining ones being where an aircraft intercepts a natural branch of lightning. It is possible for lightning to strike an aircraft many miles from a thunderstorm or cumulus cloud buildup.

I suppose it's understandable for the journos to ask about 'injuries', but the inside of the aeroplane is quite a safe place to be, with the charge flowing through the exterior of the aeroplane & not going anywhere near where the passengers sit.

Also as Kiwi said, aircraft instruments & electrical equipment can be upset quite a bit by lightning strikes, but it's not all that common these days with modern system design requirements. It's not uncommon though to get burn marks or some form of damage to the aircraft skin where the lightning enters and exits. Severe damage is rare.

Edit: Yes, I've been subject to a couple myself & the worst thing was the number of heartbeats skipped due to the loud crack & flash. No A/C damage apart from scorch marks where it exited the skin.

[ZK-NSJ]

i read somewhere that lightning can strike upto 50miles from the actual storm cell, so potentially you could be out on the deck sitting in a chair having a cold one , ZAP!

[Ultralights]

I have repaired Countless lightnigh strikes on QF aircraft, there is usually no or little damage done to aircraft, strangly every hit will be on a rivet or fastener. all it does is scorch the paint on the head of the fastener. and leave a black residue on the static wicks. i have seen aircraft come in for "c" checks and snag over 100 lightning strikes.

apart from the flash, and slight thumping noise, you would never know you were hit.

[The Enema Bandit]

Arseholio, oops, I mean Cornholio, has gone very quiet. How about a reply Cornholio?

[Cactus Jack]

Actually, I have been sitting in seat 1A in a 747 when there was a strike to the nose cone just a few feet in front of me. Loudest bang I've ever heard. Scared the sh1t out of me. Only damage was some missing paint on the radome and some soiled trousers.

[EPIRB]

I've had two. One in a 737 that sounded like a bomb going off, bruised the side of my knee when I whacked it against the control column with fright and my ears were still ringing when I got home. The second one was in a 747 and it was a very mild hiss.
Ultralights, what happens to the little bits of wire in the static discharge wicks after a lightning strike?

[Ultralights]

a lightning strike usually will not do anything to a static wick, lightning usuall enters AND exits via a fastener somewhere on the fuse or wings. but of it does exit via a wick, nothing much is noticable except melted plastic coating, or burn marks around the wicks fasteners if its mounted on a composite panel, and the wick mounted to composite structures are bonded to metal straps that are layed up in the panel.

the wicks mainly dissipate static built up from aerodynamic friction.

I have seen a video where a F4 Phantom was deliberatly flown into lightning storms by NASA to study the effects on fuel vapours etc etc , lightning hit the top of the wings, and exited through the bottm of the wing or it would hit the top of the fuse, and exit through the horizontal stab. (elevator) the lightning would hit and exit at the same instant. one hit even got the canopy frame! scared the ****e out of the pilot! you could see him almost hit the canopy with his head he jumped that much!

the only thing i dont understand is why lightning always hits fasteners!

oh, and cornhulio, how did the pax on board the following aircraft know the flight departing before them was hit?

[R4+Z]

It could be because the rivets stand slightly proud of the surrounding surface and as such present the line of least resistance.

[WALLEY2]

Ultralights,

Very interesting stuff, as Civil Engineers we are advised that static electricity forms a reverse bolt first. ie: from the object to the charged air surrounds, like twigs at the top of a tree, the lightning source also does this in that there are preliminary static electric twigs feeding out from the highly charged area. The bolt occurs when one of these sets of twigs connect, and a route for a huge voltage discharge is now available.

This is why sometimes a smaller building is hit next to a taller skyscraper, in buildings the trick is to get the initial discharge upwards to occur where you want it.

This is where your fastner comes in with its elevation, comparitive bulkiness and the "turbulence" around it, the fastner would tend to serve as a static antena with twigs of exiting static electricity. Hence it or one of its many mates is at the root of the twig that forms the circuit that makes the connection that becomes the route for the bolt.

Could be wrong but there are many more fastners than larger more obvious static antena on the aircraft.

Any BOM boffins out there to advise this must be abc to you guys?

[V1OOPS]

Old Metro II's that had been in the way of a few lightning strikes, besides losing the sharp bits off every pointy fin/wing trailing edge and a melted rear nav light, typically displayed a line of paintless rivets down the side of the fuselage - all lined up along one stringer. Can't recall if any lines went the full length or if it stopped halfway at a wing root, but the dots seemed to follow an internal length of metal rather than the surface material.

[Ultralights]

i have been doing a bit of thinking on this. Electricity will always follow the path of least resistance. rivets and other fasteners are usually solid Aluminium alloy or steel alloy. both have much less resitance to elctricity than the relativly thin alloy skins (usually .063 to .125 in thick)
Frames and stringers both are a lot thicker than the skin attatched, and provide less resistance.

part 2, i would like to do a little bit more research into, the reverse strike, with the twig electron paths, When aircraft are struck, they are usually travelling at cruise speed at altitude, cruise speed being approx 900Kph. at these speed, the twigs wont have time to form on the aircraft and reach a contact point to initiate a strike, as the aircraft will have travelled through the electrified air withing a second or 2. my theory is the 2 charged arear have almost made contact when the aircraft flies through them, and provied an alternative, more rapid path for that second or 2 allowing the strike. as i said, this is just my speculation, and i will try do do a little reasearch into this matter.

what do you think?

[WALLEY2]

I am not sure and see your point. I do not know the speed of a bolt we see it progress so it is not the speed of light- however electricity flows at the speed of light and if you turn on a search light viewed side on it is instantly there for the fulll length.

Clearly need a BOM or scientist for this one.