STEEP DES AFTER xxxx

[DonTV 0]

Flying PMDG737-700NG SAME-SCEL with VNAV and LNAV selected, near SAFEL (before reaching) with a constraint FL130A (At or Above) the ND start show curve course line (the white one) indicating a turn to the opposite of LESTA de next fix. Before reaching SAFEL the FMC display STEEP DES AFTER SAFEL this is because LESTA (the next point after SAFEL) must be crossed FL090A.Reading some topics in Internet, sugest that the diference from FL130A to FL090A in a short distance the FMC with his profile can't acomplish and display the warning, but the problem is that the FMC not continue to LESTA and start a turn to the opposite and intend to return and the aircraft start one side to another and of course out of route.I intended a modification in constraints like modifing FL090A at LESTA and establish FL110A because this acomplish with regulation, but the FMC do the same start one side to another and lost the path to LESTA.Thanks in advace, for your comments.

[downscc 1,327]

The message is an advisory message, not an error. The descent angle (not rate) is 4000 divided by the distance between SAFEL and LESTA, if the angle is greater than about 250-280 ft/nm then you need to use piloting techniques instead of automation to stay on the vertical profile. I'm not familiar with your area, but we have the same thing in lots of locations in US too. The first priority is getting slowed down such that the angle doesn't require an excessive descent rate.

[DonTV 0]

The message is an advisory message, not an error. The descent angle (not rate) is 4000 divided by the distance between SAFEL and LESTA, if the angle is greater than about 250-280 ft/nm then you need to use piloting techniques instead of automation to stay on the vertical profile. I'm not familiar with your area, but we have the same thing in lots of locations in US too. The first priority is getting slowed down such that the angle doesn't require an excessive descent rate.

Estimated downscc I know isn't an error only a warning, the problem. I am working now with speed, but still call my atention why the FMC not goes to LESTA al lost the navigation.

[downscc 1,327]

Are the fixes in a STAR or are they part of a flight plan that you entered? Have you reviewed the legs page of the FMC to make sure there is no discontinuity.Some routes that have arcs are not well preserved by Navigraph, and any arc should have several pseudo waypoints within it to define the arc...sorry, I am not familiar with your flight.

[DonTV 0]

Are the fixes in a STAR or are they part of a flight plan that you entered? Have you reviewed the legs page of the FMC to make sure there is no discontinuity.Some routes that have arcs are not well preserved by Navigraph, and any arc should have several pseudo waypoints within it to define the arc...sorry, I am not familiar with your flight.

The fixes are from a STAR, not entered by me. The whole route was checked and not have discontinuities. Todays ocurrs that I modified speeds and some constraints, but VNAV not acomplish. I will be investigating, now I will put a user fix in the middle of the arc to check the no normal operation.Thanks for your reply.

[DonTV 0]

I used iFly 737-700 in the same route same SID and STAR, and not problem, so that or PMDG FMC not operate well, or perhaps the AIRAC have some differences. This last chance will be checked with next AIRAC.

[ronzie 21]

I had one instance I tried based on another users post where the NG turned in the incorrect direction in an arc approach. I added pseudo waypoints to the AIRAC but no dice no matter what qualifiers I used with the waypoint for turning instructions.That thread is in this forum as http://forum.avsim.net/topic/337237-problem-with-the-fmc/ .It should be noted that arcs are accomplished with "local" soft waypoints coded into the AIRAC procedures and use labels that are not necessarily globally unique. The result of not using these with the proper turn were horizontal overshoot and a steep descent.

[DonTV 0]

I had one instance I tried based on another users post where the NG turned in the incorrect direction in an arc approach. I added pseudo waypoints to the AIRAC but no dice no matter what qualifiers I used with the waypoint for turning instructions.That thread is in this forum as http://forum.avsim.n...m-with-the-fmc/ .It should be noted that arcs are accomplished with "local" soft waypoints coded into the AIRAC procedures and use labels that are not necessarily globally unique. The result of not using these with the proper turn were horizontal overshoot and a steep descent.

Estimated ronzie I read the thread, and I like you said some wypoints "are local ones", but in this case SAFEL and LESTA appears in Jeppesen UMKAL 8 Arrival and in FMC of both iFly and PMDG, the trouble is with PMDG. Fliying 737 with iFly the aircraft drived by FMC not problem, with PMDG the problem that I reported after SAFEL the FMC start side to side and lost the navegation. I investigated a lot, now I am waiting for next AIRAC to test the FMC, by the moment I keep fliying iFly.Thanks for your coment, I take care about DME Arc with intermediates fixes, till now I not test the FMC in an arc, this is my next steep.Happy Landings Captain.