FMS Progress bug (maybe)
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@Black-Square I encountered a situation while VOR hopping in Starship that may or may not be a bug.
At one point, the first VOR on the FMS Progress page was one I had already passed, and its Distance value was increasing, as it should. But the waypoints below it also increased, which they should not do.
One could make the case that a passed VOR shouldn't be on the FMS Progress display to begin with, though it is possible to cause that situation.
Curious to know if this is a bug, an edge case, and how it works in the real aircraft.
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@jmarkows said in FMS Progress bug (maybe):
Did manual sequence get enabled instead of auto?
I don't think so. I had to divert some distance around a VOR due to weather, and evidently the off-track distance was enough to not pick up that the VOR had been passed.
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@jmarkows said in FMS Progress bug (maybe):
Did manual sequence get enabled instead of auto?
I don't think so. I had to divert some distance around a VOR due to weather, and evidently the off-track distance was enough to not pick up that the VOR had been passed.
@MarkS in that case that sounds right to me… the FMS thinks you still need to go to the target VOR and then to the other waypoints after that, and it will have no way to know you went around the VOR and proceeded to the next one. Therefore it’s still adding the distances up. I’d recommend going into SYS CTL and selecting MAN SEQ (or MAN LEG?) and then advance the waypoint so it knows you’re heading to the next one instead, then back to auto.
I’m trying to think through this scenario in modern FMSs I’ve used (777, A320, 737) and I think they’d also have similar issues if you don’t re-sequence your flight plan waypoints after breaking off from the planned route.
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@MarkS in that case that sounds right to me… the FMS thinks you still need to go to the target VOR and then to the other waypoints after that, and it will have no way to know you went around the VOR and proceeded to the next one. Therefore it’s still adding the distances up. I’d recommend going into SYS CTL and selecting MAN SEQ (or MAN LEG?) and then advance the waypoint so it knows you’re heading to the next one instead, then back to auto.
I’m trying to think through this scenario in modern FMSs I’ve used (777, A320, 737) and I think they’d also have similar issues if you don’t re-sequence your flight plan waypoints after breaking off from the planned route.
@Iconography the easy fix was just to do a DIR to the next waypoint (VOR) and then everything aligned properly.
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I think I've talked myself into this working as designed. The progress page reports the distance from your aircraft to the first waypoint, and the distances between subsequent waypoints. If you are flying away from the first waypoint, all of the distances will increase, which is what I saw the other day.
In that case though, I was flying away from the first waypoint and towards the second, which caused a little cognitive dissonance (why is the distance to the waypoint I'm flying towards increasing, not realizing until later that the distance is not the distance to the next waypoint, it's the distance from your aircraft to the first waypoint and then the second).
