Device: iPad 10th Generation
Operating system: Latest
I walked away from my device (with LNAV enabled) for a while whilst in flight. When I left it, I was just northwest of Havana, at waypoint ILARA. I verified everything was input properly. I just returned to prepare for my arrival, and noticed that it had decided to randomly skip waypoints PUTIM and CANEY, and go right from URKON to IMADI. There’s nothing out of the ordinary in my autopilot panel to suggest a human error.
What happened here?
Hello!
Best would be if you could share how things are looking from the app itself. 3rd party sites isn’t really the best thing to look at here :)
Thanks for the swift response. I uploaded from InfiniteInfo because it was a better visual representation for the unexplained deviation. Here’s what it looks like from my end.
The only logical reasoning I can see if that the IMADI leg was activated by you accidentally as soon as you passed URKON. Could have been even sooner actually.
Everything outside of that will purely be speculation to be entirely honest.
This happens to me as well, usually when using the “GWAVA2” sid when departing from Miami towards the south.
After GLAMS, LRODD should be next and than URSUS but when I pass LRODD it sometimes skips URSUS and heads straight to the next fix
🟦 = the path it takes
🟪 = the path it SHOULD take
Ignore my awful drawing btw
I see this as a win as it takes added flight time off. I do understand it isn’t realistic though. But sometimes I fly in a tight schedule so if this is time saving why worry?
Am I understanding this? The prior two waypoints you have so close together the second would have been skipped, and the turn was made to intercept the south leg correctly.
I can’t see anything wrong(?). You are heading to the next waypoint properly aligned with the leg formed by the next and prior waypoint roughly north that you say was skipped (taking into account the second of the two tight ones that would have to have been skipped due to speed and turn timing).
LNAV has to initiate the turn with enough lead time so, hopefully, you don’t overshoot. Note that wind (GS) may affect how early the turn begins.
Wind will affect how early you turn, but it shouldn’t cause you to skip 2 entire waypoints. Plus, winds aloft were like 18 knots.
Those two waypoints are too close together. It will briefly try to do it but move on to the next resulting in a path like that.
I don’t think they are. There’s about 12NM of separation between the two.
That’s not enough for a turn of that magnitude. You’d have to have a rather slow GS (under 200kts) to accomplish it.
As I indicated before, by visual inspection alone, the turn to the south bound course appears entirely appropriate due to the speed and angle of course change. And that second of the two very close waypoints would have been triggered and bypast quickly for the purpose of maintaining the course.
You are tracking right on the leg after all, with no course deviation apparent.
Thanks for the insight! Much appreciated.
