Lightning Strikes Gliders

As both a glider pilot and a lightning guy, I have kept an eye on this
topic for quite a few years.

I was peripherally involved with the UK ASK 21 accident and received
some unpublished reports from a colleague who was one of the
investigators. The glider in this British incident became part of the
circuit of an unusually powerful positive lightning ground discharge.
It entered one wing, puncturing the fiberglass and flowing down the
control pushrods. The current was so high, it collapsed the pushrod
tubing. Arcing between metal fittings behind the pilots provided the
pressure that both deafened the pilots and blew the canopy off. Damage
to the wings was catastrophic. Investigators concluded that the
lightning current flowing through the glider was greatly in excess of
laboratory test currents used for certification of aircraft (although
gliders and other plastic aircraft are usually not subject to these
tests).

Most aircraft lightning strikes are cloud discharges triggered by the
plane itself and involve quite modest currents and energies. Glider
strikes usually also fall in this category. I inspected an ASW-27 that
was struck by lightning in South Africa a couple of years ago. The
discharge entered the nose, exited through the tail and left just a few
small holes with no major structural damage. Most electronic
instruments were smoked, however.

Interestingly, direct pilot injuries from the lightning seem to be
minimal.

If you are going to regularly fly around or into thunderclouds, I
recommend a strong metal glider and a freshly-packed parachute!

Mike