In the early days of the 742 we 5th podded from LHR to MIA, with very little information, but it worked ! Subsequenly an ASI overlay was provided with the speed limits for future flights (290kt / M 0.85 I believe) Above those speeds a light harmonic vibration was noticed. For added interest it was the first flight in a 742 for all of us. (G-BDXB 9/8/77)
The original plan was to route via JFK, but the Captain wisely suggested non-stop which was easily achieved. Sorry about the 20+ staff pax who were offloaded !
I think a photo even made the front page of the Miami Herald - "5 little engines" was the caption if my long term memory is accurate.
p.s., The 3 engined VC10 and 5 engined Vulcan (Olympus for Concorde) were regularly seen in the Filton Area many moons ago.