Fincastle, the Atlantique 11 was viable, The Tyne is as reliable as modern turbofans, and economical to boot. The 4 engine requirement was based on obselete thinking. When I said that to visiting VIPs at Kinloss about 1970, I was ordered by the boss to repair to the mess during any future VIP visits. We could have had a hugely less expensive maritme force with a lot more units on task. Still, its history now.