ATR FMS VNAV PATH calculation is bugged in version 1.0.8

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Are you using Developer Mode or made changes in it?

no

Have you disabled/removed all your mods and addons?

yes

Brief description of the issue:

when WINDOW altitude constraints are present the FMS calculates a CROSS ALT wich is equal to the maximum altidude allowed. After doing INIT (weight and cruise level) , the FMS recalculates a CROSS ALT wich often violates max altitude allowed in the WINDOW waypoints. Furthermore i noticed that often a xxxxB constraint is flown as AT altidude constraint. And finally i noticed that FMS does not plan for a progressive descent during the STAR when AT OR ABOVE waypoints are present. The predicted profile is characterized by CLIMBS and DESCENTS, wich is not correct.

Provide Screenshot(s)/video(s) of the issue encountered:

Detailed steps to reproduce the issue encountered:

insert this plan in the FMS:

LIMJ/28 GEN6E GEN M859 LUMAV DCT OTGIG OTGI2E LIPZ/LAREN.I04RX

DO NOT manually change any altitude constraint (depicted in red in the picture)

Check calculated ALT CROSS on RNAV STAR waypoints. it is not coherent. for exmple: PZ730 is coming AFTER PZ735 but predicted ALT CROSS on the first one (depicted in black in the picture) is HIGHER than that of the second!!. Consequently the aircraft will do a climb between the two, wich is not expected.

furthermore, examine the CROSS ALT at every WINDOW waypoint of the STAR. Then do INIT and recheck all WINDOW waypoints. ALT CROSS on many waypoints will change and U ll see that altitudes constraints are often violated by predicted ALT CROSS. Here is an example:

PC specs and/or peripheral set up if relevant:

xbox

Build Version # when you first started experiencing this issue:

1.32.7.0


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Do you have the same issue if you follow the OP’s steps to reproduce it?

Provide extra information to complete the original description of the issue:

If relevant, provide additional screenshots/video:

Have you tried doing weights, then perf init, then flight plan? That is the proper procedure, and it is possible changing this is resulting in improper calculations.

i don t think that it is related to the sequence U re talking about.

The problem is that the VNAV PTH calculation is incoherent.

FMS should never ever command a climb between two waypoints during a STAR if both are costrainted to 5000A and this is exactly what s happening.
It should calculate a progressive descent path or a level off between the two, but not a climb.

Neverteless i ll try the correct sequence😉

Fixed in a previous update.