I heard a roumor that this incident when it lost its engines one of the crew was out walking around the cabin at the time.
From Wikipedia:
Shortly after 13:40 UTC (20:40 Jakarta time) above the Indian Ocean, south of Java, the flight crew (consisting of Senior First Officer Roger Greaves and Senior Engineer Officer Barry Townley-Freeman while Captain Eric Moody was in the lavatory) first noted an effect on the windscreen similar to St. Elmo's fire.
British Airways Flight 9 - Wikipedia, the free encyclopedia