IXEG737-300: the problem of fly over route points

[WingtipLight]

I don't know why every points this 737-300 select "leap", rather than "tangency". This situation will lead to plane couldn't fly along the purple line. When I want to approach, I couldn't accurately make a turn from four side to five side. Approach, departure and cruise also appear this problem. I try to change autospeed or input a suitable speed in LEGS, but this problem still exist.

[Litjan]

To me it looks like the turn radius is calculated wrong - either you are not flying it at the speed that the FMS "thinks" you should fly it, or there is some data missing for the FMS to calculate it correctly (weight, altitude,...)

If you use the FMS correctly, the turn radius will be calculated correctly and the plane will fly it accurately.

Have you watched the tutorial videos for this aircraft?

[tkyler]

There's not quite enough info in that screenshot to make a determination.   You can execute an LNAV route without PERF data and when doing so, the route defaults to approx 210 knots (small radius turn) as it can't calculate speeds without some basic info.  Now in such a case...if the real FMS...in the absence of "plan data", uses real time speeds / altitudes and adjusts the routing dynamically in real time...that would be new to me and something I'd want to learn more about. ..but I can think of several scenarios where an FMS just can't know what exactly you're doing and doesn't want to take on the responsibility of "guessing".

tk

Edited November 7, 2023 by tkyler