In the "good old days", tank entry utilised state of the art safety procedures and equipment.Air was supplied from a V Dub engine with 1(or 2?) cylinders isolated and utilised as the compressor (air quality non existant), and, air hose disconnects that had a habit of disconnecting over a rib only when you got to the furthest corner of a 747 wing tank.Venting was carried out while you had smoko.Glad to see OH&S and adherance to the AMM has improved and I'm still alive to see it.