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Mike777

Active Route No Altitude Info After Change to Route 2 - VNAV won't engage

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Hi, everyone,

 

Today I had a rather perplexing event.  I was in cruise, Route 1 active, everything OK.  Then I modified a STAR and runway with transition.  In the course of doing so, I realized that I had somehow selected Direct to a waypoint in the STAR, thus wiping out the intervening enroute waypoints.

 

To solve this problem, I loaded the entire route in Route 2 from disk,  moved the next waypoint aheadof my position up to be the active waypoint  (rather than the first waypoint going back to the beginning of the flight), and activated Route 2. 

 

The aircraft followed the route OK in LNAV, but would not engage in VNAV.  No altitudes were showing on the FMC legs page for subsequent legs except for restrictions included in the STAR (although my current Perf entry and I believe VNAV cruise entry had the correct altitude, FL350, after two auto step-climbs).  The progress page did not show any predicted arrival time or expected remaining fuel.  Active Sky Next, latest beta, was active, and I loaded current wind information, but it made no difference. (I did have a problem later with ASN, but I don't see how it's related to this one).  I also entered the current FL either in the active waypoint or the following one, but the altitudes did not propagate down the list of waypoints.

 

To solve this problem, I went back to Route 1, re-entered the remaining enroute waypoints, activated the route, and lo and behold, altitude information and predicted times returned, Progress display returned to normal.

 

Did I do something wrong or is this a bug?

 

Thanks,

Mike

 

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When using the route 2, have you tried to re-enter the cruise altitude on the VNAV cruise page?

Or also re-enter the altitude and CI on the PERF page?

 

I don't often switch to RTE2 but I don't recall having any issue with it. I'm going to try to reproduce your situation to see if I get the same behaviour.

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When using the route 2, have you tried to re-enter the cruise altitude on the VNAV cruise page?

Or also re-enter the altitude and CI on the PERF page?

 

Hi, Romain,

 

I believe the altitude was already in VNAV Cruise, although I'm not sure.  I know it was showing on the PERF page.  Not sure what "CI" is.  I don't think I re-entered the altitudes on either page as they were already there.

 

Thanks for your quick response!

 

Mike

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I reproduced the situation and got exactly the same behaviour... Now I'm gonna dig also for the answer into the forum, manuals in case you would have missed an information somewhere.

 

FYI, CI is Cost Index I tried changing it on the PERF page and it didn't fix the issue. And you cannot change the altitude in the PERF page once in flight, only on the VNAV page.

 

EDIT: I have found 2 other topics talking about the RTE 2:

http://www.avsim.com/topic/422698-route-2/

http://www.avsim.com/topic/455719-route-2-automatic-clearing/

 

I didn't swith to HDG (remained in LNAV) before activating the RTE2.

I will retry to see if it gets better.

 

EDIT2: Wow I succeeded in messing up everything!  :Devil:

I went to the point where I had no more VNAV path available on both RTE1 and RTE2 and not able to flush neither RTE1 nor RTE2 while inactive on flight...

 

When changing the destination airport on inactive RTE2, the new destination airport was accepted but the route remained and was not flushed!

I did tried this also on inactive RTE1 (after activating RTE2) and got the same. impossible to flush it.

 

I get to start the test again from ground and from scratch!

Edited by Budbud

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I reproduced the situation and got exactly the same behaviour... Now I'm gonna dig also for the answer into the forum, manuals in case you would have missed an information somewhere.

FYI, CI is Cost Index I tried changing it on the PERF page and it didn't fix the issue. And you cannot change the altitude in the PERF page once in flight, only on the VNAV page.

 

Thanks, Romain, for your efforts!  I think we may have a bug here.  The two threads you mentioned are very interesting too!  I rarely use Route 2, so i haven't experienced problems w/ flushing the inactive route.  I would have thought it wouldn't be that hard.  Maybe if you change the origin airport instead of the destination.

 

Also learned something useful -- apparently according to 777simmer we are supposed to copy Route 1 into Route 2 as part of pre-flight, among other things.

 

 

Mike

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Maybe if you change the origin airport instead of the destination.

 

I tried that too but it was not accepted.

I found the two posts very informative as well.

 

With regards to the RTE2, I think it may not work properly in the PMDG's 777 or at least not with full features as the real one.

Unless I have missed some statement from PMDG regarding limited feature on the RTE2 or already acknowledged bug, it may deserve a ticket to the support.

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To solve this problem, I loaded the entire route in Route 2 from disk
Mike

What do you mean by this statement. The word disk is throwing me. What disk do you mean? Or was there even a disk involved?

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I guess he means loading the route using route request datalink function. At least it is what I have understood and used to reproduce the test.

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I assume that the datalink route loads to RTE1.. but it's just an assumption.

 

Lack of VNAV can simply be a result of the FMS unable to resolve the vertical path calculation. This could be related to the root problem rather than the problem itself.

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I assume that the datalink route loads to RTE1.. but it's just an assumption.

 

You have the route request option available from both RTE1 and RTE2 page. I had no route loaded on RTE2 and could load a route with this option on RTE2 the same way we do on RTE1.

 

When I tried to activate the route 2, I was at the initial cruise altitude set on the PERF page and close the beginning of the route.

I agree that something definitely prevents the FMC from resolving the vertical path but I can't see what.

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I agree that something definitely prevents the FMC from resolving the vertical path but I can't see what.
Romain

Tonight I will do EDDF-KIAH and set RTE 1 for a SKNRD4 ILS 9 and when at initial cruise altitude I will set RTE 2 for DOOBI2 ILS 27. During the flight I will make RTE 2 the active route and see what happens. I will keep track of the keys, pages, clicks, etc. that I use.

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Thanks to everyone for responding!

 

 

Mike

What do you mean by this statement. The word disk is throwing me. What disk do you mean? Or was there even a disk involved?

 

 

 

I assume that the datalink route loads to RTE1.. but it's just an assumption.

 

Lack of VNAV can simply be a result of the FMS unable to resolve the vertical path calculation. This could be related to the root problem rather than the problem itself.

 

 

 

You have the route request option available from both RTE1 and RTE2 page. I had no route loaded on RTE2 and could load a route with this option on RTE2 the same way we do on RTE1.

 

When I tried to activate the route 2, I was at the initial cruise altitude set on the PERF page and close the beginning of the route.

I agree that something definitely prevents the FMC from resolving the vertical path but I can't see what.

 

 

You can load a route into Route 2 by using the request function.  I should have been clearer, but that's what I mean by "loading from disk."   I did this in flight, after I messed up route 1 as I described in my first post.

 

Dan, the problem is that the flight plan in Route 1, when I added back the missing waypoints, calculates altitude and other VNAV information just fine, but the identical flight plan in Route 2 does not.

 

Romain

Tonight I will do EDDF-KIAH and set RTE 1 for a SKNRD4 ILS 9 and when at initial cruise altitude I will set RTE 2 for DOOBI2 ILS 27. During the flight I will make RTE 2 the active route and see what happens. I will keep track of the keys, pages, clicks, etc. that I use.

 

 

I experimented a little more last night.  If I use the Route Copy function, copying Route 1 into Route 2, then in Route 2 VNAV info is calculated and works OK.  But if I load the flight plan into Route 2 by using the Request function, it does not work OK, even though Route 2 is active and is controlling LNAV, and the flight plans are identical (after I moved up the next waypoint from my location to be the next waypoint in the Route 2 flight plan - because when I used Request in Route 2, it loaded the entire flight plan, beginning to end).

 

Note that I am using the Request Route function (in Route 2) in midflight, which may have something to do with the issue.  So, Michael, if you use Route Copy to copy your EDDF-KIAH plan from Route 1 to Route 2, it will probably work OK.  Also, I am guessing that there may be a difference if you load Route 2 on the ground using the Request function, rather than in the air.  I know the problem happens when I use the Request function in Route 2 while in the air.

 

I also want to mention that 777Simmer, in one of the threads Romain linked to above, said that SOP is to copy route 1 to route 2 during preflight.  If I had done that, I think Route 2 would have worked fine after I messed up Route 1.  But I still don't understand why the FMC can't resolve the VNAV data in Route 2 that it can resolve in Route 1 with the identical flight plan.

 

Finally, I want to mention that the aircraft did not always follow the waypoints, either in Route 2 or Route 1 after my initial problem.  At the time I assumed it was because I entered the wrong waypoint as next or some other error, and eventually it went back to following the plan,  but now I am wondering if there was some other FMC issue.  I did not get any "not on intercept course" messages.

 

I have at least one autosaved situation from this incident and will go back and check further this evening, if time allows.  The plan was KSFO-LFPG, and I was at cruise altitude not too far from TOD when this incident happened.

 

Thanks again to everyone!

 

Mike

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So, Michael, if you use Route Copy to copy your EDDF-KIAH plan from Route 1 to Route 2, it will probably work OK.
Route Copy is what I use to copy 1 to 2 during the climbout. Where is the Request function located?

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Go to the RTE2 first page it is as the same place as on the RTE1 (LSK3).

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I automatically do the RTE Copy during preflight... I found that it made setting up ETOPS alternate paths a lot easier and never dug very far into the other uses for RTE2

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Go to the RTE2 first page it is as the same place as on the RTE1 (LSK3).

On the ACT RTE 1 LEGS I press LSK6 for <RTE 2 LEGS. Once on the RTE 2 LEGS page it is blank except for <RTE 1 LEGS and ACTIVATE> on line 6. Still no request anywhere to be seen. So I am just going to do a route copy and finish the flight.

 

This plane is the 777F. Maybe the CDU/FMC is different on the 77LR. 

 

Is this Request procedure detailed in any FCOMs or FCTM?

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On the ACT RTE 1 LEGS I press LSK6 for on line 6. Still no request anywhere to be seen.

 

Hi, Michael,

 

Make sure you are looking at the Route page in Route 2, not the Legs page.Try using page up to get to the top of the route listing.  You should see the departure and arrival info, and just below the blank for Runway entry, at LSK3 Left, you should see REQUEST.

 

I did some searching for Route 2 in FCOM 2, but I mainly found stuff about the Comm page on the MFD, which looks like it's not modeled (understandably, since normally there's no-one to communicate with).

 

Mike

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Make sure you are looking at the Route

It would help if I would not only read the posts but comprehend them also. I see it now. It's on the same page as RTE COPY. What is the advantage of the request function when compared to route copy?

 

The following details how I change from RTE 1 to RTE 2 after using the RTE COPY.

Left CDU on ACT RTE 1 LEGS. Right CDU on PROGRESS 1/4. Click LSK6 <RTE 2 LEGS. Move current waypoint to the first waypoint listed on Page 1 of RTE 2 LEGS. Press RSK6  ACTIVATE>. Press EXECUTE key. Press LSK1 twice. Press EXECUTE key. Now ACT RTE 2 LEGS has all the information including waypoint, distance between waypoints, speed and altitude and RTE 1 LEGS only has waypoints and distance between them. Speed and altitude are blank. LNAV and VNAV remain engaged during whole process. Right CDU still has some partial information left from RTE 1. Press LEGS key. Press LSK6 < RTE 2 LEGS. Press PROG key and the information on PROGRESS 1/4 is current.
 
I just switched back to RTE 1 since it has the correct STAR and APPROACH. RTE 2 had a different STAR and APPROACH but it was to the wrong runway.
 
 

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Hi Michael,

 

as mentioned by Mie on an earlier post, it seems that using the route copy function there is no issue to activate the RTE 2. The issue occurs when the RTE 2 is downloaded using the route request function.

 

My guess about the RTE 2 request utility would be if you had to reroute because of weather on a better route, the dispatch could have a better route available during the flight and you could download it.

I don't know however if you would be allow to modify the whole route or part of the route in flight ATC-wise.

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See page 88 of the Introduction, Page 12/13 FMC DATALINK, AUTO PREFLIGHT UPLINKS. I believe the keyword here is preflight. It can't be done once you leave the ground.

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You are right...

Then what's the purpose of the route request on RTE 2? Download a second different route from the dispatch on ground?

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What is the advantage of the request function when compared to route copy?

 

Hi, Michael and Romain,

 

I ran into a problem because I messed up my primary, Route 1 flight plan.  If I had copied Route 1 to Route 2 as part of pre-flight, it would have been easy to fix -- I could have just gone to Route 2, moved my next waypoint to the top, activated, and everything would have been fine.  But I didn't do a Route Copy at the begiinning.  So I thought I could just load the entire flight plan into Route 2.  I did this by doing Request Route in Route 2.  It did load the plan (from the file saved in the PMDG>flight plans folder) and I could edit it to bring the next waypoint in front of me to the top of the plan.  But it didn't have the altitude data so VNAV wouldn't engage and I couldn't get time predictions, such as TOD. 

 

The only way for me to fix the problem was to manually re-enter the missing parts of the flight plan in Route 1.  That worked fine, and it wasn't too difficult to do since I had completed most of the flight.  But suppose I had been near the beginning, rather than the end, of a ten hour flight?  I would have had to enter all the airway and waypoint information manually.  Kind of annoying when the entire flight plan was readily available on my hard drive in the PMDG>flightplans folder. 

 

The Intro manual does discuss using Request Route in a couple of places as a ground operation.  But it doesn't discuss the situation I faced, in mid-flight.  Here we get into a gray area -- what is being simulated?  Can the pilot request a new flight plan or a repeat of his/her existing flight plan using a data link in mid-flight?  I don't know.  But if he could, why would the altitude data not be calculated by the FMC? 

 

 

 


My guess about the RTE 2 request utility would be if you had to reroute because of weather on a better route, the dispatch could have a better route available during the flight and you could download it.

 

As Romain said, couldn't there be situations in mid-flight where the pilot needs to upload a new route using datalink?

 

I searched Tutorial 1 for "Copy" and I didn't find anything about Route Copy, but I could have missed it.  Apparently it is SOP to set up the route, presumably in Route 1, and then copy it into Route 2 during pre-flight, as both Dan and 777Simmer have suggested.

 

I think I will file a kind of query/information/bug report and see what PMDG says.

 

Mike

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I think I will file a kind of query/information/bug report and see what PMDG says.

 

And I will be interested in the anwser you get there.

Would you post the information you will get?

I don't think it's worth opening two tickets on the same topic from two different persons.

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And I will be interested in the anwser you get there.

Would you post the information you will get?

I don't think it's worth opening two tickets on the same topic from two different persons.

 

I expect I will.

 

Thanks to you and Michael for your help!

 

Mike

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