Assume that it is below 10,000ft so the 240/10000 speed restriction would be active on the descent page. I know that the autothrottle will protect the speed going below min manoeuvring but I'm not sure where the command speed bug would be or if in fact it is even influenced by the min manoeuvre speed for that flap position. It is possible that the speed bug just looks at what the FMC is commanding as in 240 below 10,000 and then the next altitude or waypoint speed constraint ie 180/3000 at XXX. In other words in VNAV PTH the bug would be 240 kts until a deceleration to 180 was required and then it would go to 180. This would explain why the speed should be manually controlled. I spent 14 yrs on the old girl and still can't be 100% certain as to what would happen!
Last edited by cowpatz; 23rd Sep 2015 at 05:14.
Reason: spelling error