Cheers,
I have read with interest some of the email regarding lightning
strikes. It is not uncommon for airliners to attract and withstand some
lightning strikes. Their metallic bulk, attracts and their binding tends
to withstand the bolts. For the most part, however, these strikes are
"kiddies" - 'feelers' for the ultimate route to ground or cloud which
has not yet built up anger. The disturbed air and exotic ions ejected
---From the engines attract an early strike. Also when the plane cuts the
route to onehalf the distance between poles, an early strike results.
Just like a bugkiller grid.
However, when the feelers establish a reduced-resistance
routing,
especially cloud-to-ground or vice versa, then a strike can easily
surpass 60.000 amperes at 100,000 volts. NOTHING can resist that, and
because of truly sparse bonding intrinsic in glass structures, the
strike can raise the temp well above all protection. It blows to bits.
It is safe to say that at present there is NO protection from
adult strikes, and very little inducement to attract early attacks.
The finest protection is between the ears. I would never
approach
closer than within 15 nm of a cu nim Above the freezing level, and 25 nm
below tha FRZLVL. The greatest threat is AT the FRZLVL because of the
energy released due to changes of state. Approaching potential tornados
is also risky because, originating from the cu num roll cloud, they are
close neighbours of the worst lightning generators, and of course fierce
tornados are Van De Graaffs of immense power.
None of these threats are visible if you're IFR in cloud, so a
super briefing is the minimum - unless you have a Strikefinder or
similar
device. Somebody comes sifting out of the bottom of clouds in pieces at
least once a year, and especially in Florida/Minnesota, but cu nims, for
all their tiny UK heights are also potent bangers.
Those glider chaps (the accident report's on file a AAIB) were
incredibly lucky to be able to clear the bits before hitting silk.
Happy landings!
Ferg A064
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