767 Lightning Strike Tonight, ATL

[peterbuckstolemymeds]

I was fortunate enough this evening to experience something I never thought I'd witness: A lightning strike on the aircraft that I was SLF on. I have a couple of questions, if any pros feel like enlightening (no pun intended) me.

It was DL115 BCN-ATL, in descent thru cloud a few minutes before the turn onto final. There was a show on the in-flight system at the time so I can't say anything about where we were when it happened because the flight data wasn't showing.

It was a little bumpy at the time, nothing crazy -- I've experienced worse before at ATL -- when there was a fairly startling crack (though not ear-splitting, such as you might experience if you're near the location of a groundstrike) accompanied by a flash of light outside. The flash, too, wasn't as intense as I would have imagined but I was seated in the center of cattle class, way down the back, so I might have had a different impression if I'd been closer to a window.

There didn't seem to be any electrical disruption onboard. No Hollywood lights-flickering or anything.

Anyway, my first thought was that maybe the tail had been struck by lightning or that we'd perhaps flown very close to an electrical discharge. Other pax looked around nervously and the purser smartly made a cheery announcement that folks seemed to find reassuring. "Well THAT was a surprise, ladies and gentleman," he laughed.

Nothing from the flight deck, understandably. They'd have had their hands full without the bang, I'm sure.

So, on leaving the aircraft (I was about the last pax off so I thought the Cap'n wouldn't mind too much) I asked him whether we'd indeed been hit by lightning or whether we'd just come close. He said we'd been hit on the nose and that maintenance were already all over it. He said all they could find so far was "a chip" out of the nose. He added that Mr Boeing makes tough aircraft.

I asked him how often that happened. He smiled. I asked "Once? Twice in a career?" He grinned even more and said something like that. Not wanting to keep him from the paperwork or the bar any longer, I offered my thanks for the adventure and the safe landing and went on my way.

What I thought odd about this was that the temperature on arrival at Hartsfield was chilly... it was in the 40s F. Cooler than I would have expected for such an event to occur but, of course, I'm no expert.

I'm curious about that. And also about being hit on the nose. Is that the most likely part of an a/c to receive a jolt? Is once or twice a career a fair estimate of frequency for a prof pilot?

I also wish I'd asked the Captain what it had looked like, and how long it had taken his eyes to recover.

Anyone who has time, I'd be much obliged.

[Bullethead]

G'day PBSMM,

I've had a couple of strikes during my carreer, over 30 years so far, both in the military, Oz Airforce, and during airline operations. The temperature sounds about right, most strikes occur within 5degC of the freezing level, that is when the outside air temp is between -5C and +5C or between 23degF and 41 degF.

Aeroplanes are designed to minimise static electricity potential buildup by having discharge wicks at the wing, stabiliser and rudder tips, you can see them next time you're at an airport. By keeping the electrical potential of the aircraft as low as possible it minimises the chance that the aircraft structure is going to be a suitable path for a lightning discharge.

Nose strikes are fairly common, that's where the weather radar is and is an area of high electrical potential, but they can occur anywhere on the structure. There is always an entry point and an exit point, sometimes many such points, which generally are no larger than a tiny pinhole. Serious structural damage is uncommon.

You're right, the noise and flash is much less intense than you would have imagined. There is a recommendation to set the cockpit lights up to maximum brightness, if operating in an area where lightning strikes may occur, to minimise the flash effect but in my experience the visibility was so poor, due to torrential rain, that the effect of the flash was minimal.

Regards,
BH.

[RJ Kanary]

<What I thought odd about this was that the temperature on arrival at Hartsfield was chilly... it was in the 40s F. Cooler than I would have expected for such an event to occur but, of course, I'm no expert.>

I am not a meteorologist, nor do I portray one on television.What I can tell you is in the past twenty years or so, I have witnessed thundersnowstorms about a dozen times in Western Pennsylvania.An event that you will not soon forget........... :)

[Dan Winterland]

I reckon I've had about twenty strikes in a 25 year career. It sounds a lot, but I think it depends on what aircraft you fly and where. My first aircraft (HP Victor K2) seemed very prone and I had several in a few years. Also, the Victor used to get very impressive St Elmo's fire - inside the flight deck as well. And once, I saw ball lightning inside the aircraft - fascinating! Now, I fly around the tropics amongst lots of storms and I had three last year.

But strikes are actually quite likely in temperate zones. From my experience, strikes are likely even from small clouds and most common at the height of the zero degree isotherm. As the elecrical potential in a storm cloud is greatest near cloudbase, your experience with a surface temperature of 40 degrees f, a strike at 3000' on finals sounds about right. As aircraft have limited room to manouevre when approaching an airfield, avoidance of potential strike clouds is limited at that altitude - whereas at higher altitudes it's easier to give them a wide berth. I used to fly 747 freighters between Asia and Europe. In three years on the fleet, I had three strikes - all on approach to Manchester in the north of England!

Damage is usually rare and the aircraft acts like a faraday cage and will protect the occupants. But not always! I was struck in a VC10 on the refuelling probe above the radome. The F/O got a shock through his feet, I was transmitting at the tile and got a shock through the hand on the transmit switch down the left side of my body through my left foot. It hurt! And I'm still suffereing minor effects ten years later. Also, the lightning passed through the centre of the cabin exiting through the wingtips. Holes were burned in the probe, each wingtip, the radar and a radio blew and both compass detectors were damaged.

And lightning does strike twice. I also got a shock on my first strike which was in a glider. Lightning arced off the metal part of the airbrake lever and got me on the palm of my left hand. The shock was quite mild from this strike, the burn from it hurt more. I still have a scar from the burn.

But don't let it worry you. Just make sure that when you fly next, I'm not the pilot!

[Wycombe]

Heard an Air Canada flight on climbout from Heathrow report a strike only 2 days ago (Sunday 13th). Just reported it, asked for a weather avoidance heading, then carried on to the Atlantic.

[peterbuckstolemymeds]

BH, great post. Many thanks. Didn't occur to me for a second that the weather would curtain the glow, so to speak. And turning up the cockpit lighting... jeez, great stuff. Simple concepts that were just way beyond me. :)

RJK, now weather like that would be something to see. It sounds rather mind-blowing to watch let along fly thru. Who knew that weather like that even existed? Thanks so much!

And Dan, same to you, Sir. Eye-opening stuff. Special thanks for the math you did for me. And those shocks of yours? All I can say is Yikes! If nothing else, I'm glad for you that you can "dine out" on such great stories. But rather you than me! :)

Wycombe, nice tail-piece there (again, no pun intended). Thanks to you, Sir. Very nicely puts into perspective the real threat, or the ability of aircraft to throw it off... or both!

Thanks again to you all. Be safe!

[A2QFI]

I agree with the perception that the nose area is vulnerable. I had a lightning strike, at night, while medium level in an F-4. No major effects, except that the radar stopped working, which didn't exactly surprise me! However, when I saw the aircraft in the hangar the next morning the whole of the interior surface of the radome had de-laminated. It was hinged open and full of great coils of firbre glass - rather like a peeled onion. Nothing visible at all from the outside but a bit of a mess inside!