KDTW......MIZAR3 arrival to ILS21L// ADDED LOG FILE

[Tim013]

Had an odd thing happen yesterday.  I was flying from KMDW to KDTW via this route: LEWKE GIJ LFD MIZAR3.  Everything was going great using LNAV and the MCP for vertical guidance. After passing MIZAR intersection and half way to RAZIM intersection, the FMC popped up the message "waypoint not found", and the 737 immediately entered a right turn.  I turned off LNAV, and got back on the beloved magenta line via the MCP and HDG control.  Once I was back on course, I changed the FMC flight plan by moving TIGRZ intersection to the next waypoint (wanting to bypass RAZIM), and then activated LNAV again.  The 737 tracked the new course just fine until about half way to TIGRZ intersection, and then the same "waypoint not found" message occured, and bingo, another hard right turn. 

What is odd is that the route, including the STAR and approach were entered before takeoff, and accepted by the FMC as being valid.  There were no discontinuities.  Strange it would navigate to a fix, in this case, two different intersections, and both times, suddenly say they don't exist.

 

I'm going to recreate the flight today, and see if it can be reproduced.  Anyone have this type of thing happen to them?

The weird thing is, I've had hardly no issues with this bird at all.  It's been great for me from day one, and I've been loving it.

Final note:  I'm using Navigraph AIRAC cycle 1607, just updated a couple days ago.

Tim

Edited June 30, 2016 by Tim013

[Defiance_co]

Hiya,

Not had it myself, but i have cycle 1607 installed, if i get chance tomorrow i'll try the same route settings

And to agree, i've been lucky as also i've had no drastic problems that wasn't fixed with a very fast hotfix

Heck, can't live without this old girl now

Tony

 

[Tim013]

Tried the flight again.  I was mistaken.  The FMC doesn't give the message "waypoint not found", it warns "unable crz altitude."  Both times, at the same place, the warning popped up, and a 90 degree turn to the right was commenced, then that 90 degree to the right heading was held indefinitely. 

There have been two revisions to AIRAC 1607 since it first came out, and this flight just now was with the latest revision number 2.

Tim

[Tim013]

I've tried the flight again a few more times, with the same result.  The last time, I even used simbrief to get real weight and fuel numbers to make sure I wasn't arriving too heavy, and tripping the "UNABLE CRZ ALTITUDE" message, but no joy.  The arrival breaks off in a 90 degree turn to the right.

I'm puzzled.

Tim

[mmerelles]

What is your departure / arrival runway / procedures you programmed in? i will try to replicate your issue

navigraph released a rev2 for 1607 /ixeg. have you tried latest revision just in case?

Edited June 29, 2016 by mmerelles
misspelling

[Tim013]

Yes, I have the Revision two of 1607 from Navigraph.  I had this happen with the original 1607 as well.  Good idea to always check that.

So, it's a common flight for me. 

KMDW to KDTW

Route:  LEWKE GIJ LFD MIZAR3 departing from Midway on 13C or 04R, and landing at KDTW on runway 21L.  I use the MIZAR3 LFD transition, and the COUNT ILS21L transition.  I fly it with LNAV for lateral guidance, and use the MCP for vertical guidance......no VNAV at all.

 

===  I added the last log file in case any of the developers are interested. ===

Tim

GizmoLog.txt

Edited June 30, 2016 by Tim013
Added Gizmo log file.

[Litjan]

Hi guys,

we always need the IXEG_FMS_debug.txt file to review any flights. It is in the aircrafts root folder and will be updated every time you press EXEC.

Thanks, Jan

 

[Tim013]

Jan,

OK.  I haven't flown the IXEG 737 since my last attempt at this flight, so I will post that log when I get home from work today.

Thanks,

 

Tim

[Litjan]

3 hours ago, Tim013 said:

Jan,

OK.  I haven't flown the IXEG 737 since my last attempt at this flight, so I will post that log when I get home from work today.

Thanks,

 

Tim

Sweet, thanks!

Jan

 

[Tim013]

One FMS debugging log coming up.

 

Tim

IXEG_FMS_debug.txt

[Tim013]

Here's another one I just did from KFWA to KDTW

Route: EDGEE MIZAR3  with runway 21L selected.  The MIZAR3 FWA trasition and 21L COUNT intersection transition.

FMC log included.

Same deal.  After crossing RAZIM and turning on course to COUNT intersection, after a couple of seconds on course, the aircraft turned right 100 degrees, and then continued on straight and level on the new heading.

LNAV only, with speed and altitude controlled by the MCP.

I hope this helps you guys.

Tim

IXEG_FMS_debug.txt

Edited June 30, 2016 by Tim013

[Litjan]

Thanks for the report and the files!

Jan

 

[stevekirks]

Unrelated: Doesn't Jan's avatar make you smile every time you see it?  That's what I imagine I'd be smiling like if I got to fly 737's for a living...

[Litjan]

13 hours ago, stevekirks said:

Unrelated: Doesn't Jan's avatar make you smile every time you see it?  That's what I imagine I'd be smiling like if I got to fly 737's for a living...

Yeah, I was still smiling, then....Now I fly Airbus.

Jan

 

[Rodeo]

Wait, you still (find time to) fly professionally? I was under the impression that between IXEG development, IXEG support and X-Plane gateway airport design, you were basically fully booked…

[Litjan]

3 minutes ago, Rodeo said:

Wait, you still (find time to) fly professionally? I was under the impression that between IXEG development, IXEG support and X-Plane gateway airport design, you were basically fully booked…

Once those guys pay me what my Airline pays me, I will consider switching full time!

Jan

 

[Rodeo]

Right, but I mean, can you really be a full-time pilot and do all the other stuff you work on (also, aren't you married, too?), or are you on some kind of part-time deal with your airline?

Edited July 3, 2016 by Rodeo

[Litjan]

2 hours ago, Rodeo said:

Right, but I mean, can you really be a full-time pilot and do all the other stuff you work on (also, aren't you married, too?), or are you on some kind of part-time deal with your airline?

No, I fly full time. But I have a nice gaming-laptop that fits just inside my flightkit and since I am old and married, I don´t have to entertain the flight-attendants and hit the bars during night-stops anymore, I actually get a lot of stuff done .

Jan

[Dhruv]

29 minutes ago, Litjan said:

I actually get a lot of stuff done .

Jan

"German efficiency™" 

[tkyler]

Hi guys, I'm starting to go after this one.  I'm guessing that it will be related to our "look ahead algorithm" on the route.  We try and look down the route to anticipate turns and such and I have seen occassions where my "look ahead", gets distracted for some reason and says, "oohh...look at that over there".  

-tkyler

[tkyler]

Got this one fixed.  In this particular route, the problem was a very acute turn followed by a close, next waypoint  (but next WP is inside the turn radius of the acf) ...and given this specific sequence (acute turn + next waypoint inside turn radius  + next waypoint < 15 miles from the previous point ), my code did not execute a bypass, causing a route kink and all sorts of issues, including departing the LNAV early.

Here's a workaround for now (screenshot below).  Place BALAS after COUNT, (or delete TIGRZ and ROBBI).....  This gives my code in this particular case room to "complete the calculation" and you can fly this route without departing the LNAV.   

-tkyler