Airport Safety instructions state that during thunderstorms.....
The embarkation ad disembarkation of passengers, other than by airbridge should be stopped.
Aircraft and vehicle fuelling should be suspended.
All aircraft should bge correctly earthed.
Mobile crane ops to be suspended and personnel moved away from crane.
Headset operations during pushback should cease and hand signals used.
Personnel should not gather in groups and if possible remain indoors.
Hope that's helpfull. I think CAP642 contains something on the subject.
