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VERT PATH FULL-FMC message

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VERT PATH FULL appeared on the FMC scratchpad. The message could not be cleared and because of that no entries could be made into the FMC. The various pages could be accessed but no entries made. Speed and altitude calculated by the FMC disappeared from the legs pages. The hard coded altitude constraints from the ILS Approach and STAR remained on the legs pages. He is how this situation developed. Auto Step Climb was enabled. At FL390, an auto step climb to FL410 was begun by the plane. I received a message in the scratchpad saying SERVICE CELING 40800. The legs pages changed the altitude to FL410. The plan stopped at 40800. I descended to FL390 using V/S. I disabled the auto step climb. I then tried to get FL390 on the legs pages rather than the FL410. This is when the trouble started. I tried maybe five different entries into the FMC before I received the VERT PATH FULL message. I don't plan on being this high again but I am curious as to what the message meant. Any ideas on this would be appreciated.

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"The FMS has a few error messages that are unique to the sim only, primarily to trap errors in the syntax" This appears to answer the question. I found this in the NGX forum in a thread entitled "VERT PATH FULL" started February 26, 2012. It did not show up in any FCOMs for 777 or NGX since it is message unique to PMDG and not the real FMC.

 

I found this by doing a Google search for vert path full. Several returns but this appears to be the best one.

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Likely something wrong with the STAR or approach. The error means the VNAV solver couldn't calculate a solution for the descent.

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This happened to me yesterday flying the NGX from EGKK-LPFR whilst inputting the arrival details. First I selected the runway, then the STAR. No probs there. It was only after choosing altitudes along the arrival path (there were 2 altitude options on each waypoint of the STAR) that the VERT PATH FULL annunciation appeared.

VNAV disengaged and that was when I started going through the manuals in order to find out what to do but to no avail. Like the OP, googleing came up with the same result - not really helpful. So I tried resetting the FMC by inputting the company route again (I have all my routes stored and thus use Co Route option). The original route came up from the start at EGKK to the last waypoint before the STAR. The FMC then asked for the next waypoint enroute (can't remember the exact wording) but this seemed a logical step to bring lateral aspect of the route up to current location. At this point, the FMC appeared to recalculate the required VNAV path and then the whole sim froze. A bit annoying really as I was already 2 hours into the flight.

 

Flight plan was:

SAM UN621 MARUK UM195 LORKU UN866 QPR UM30 LOTEE DCT BATAX DCT BABEX DCT ALAGU

 

Airac at time was 1405rev1

I hope this info offers some insight as to what actually went wrong.

 

Best wishes,

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Likely something wrong with the STAR or approach. The error means the VNAV solver couldn't calculate a solution for the descent.

 

The STAR and runway had been in the FMC for 18 hours and not created any problem. The problem started when the plane did an auto step climb from FL390 to FL410 but stopped at 40800 feet due to service ceiling limit. Kind of an strange altitude to cruise at. So I went back down to FL390. The legs pages still showed FL410. When I tried to change that to FL390 I received the VERT PATH FULL message and speed and altitude disappeared from the legs pages and the message could not be cleared so the FMC was useless. In neither 777 or NGX FCOMs can I find this message. If it is not a message from Boeing , who is it from?

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The STAR and runway had been in the FMC for 18 hours and not created any problem. The problem started when the plane did an auto step climb from FL390 to FL410 but stopped at 40800 feet due to service ceiling limit. Kind of an strange altitude to cruise at. So I went back down to FL390. The legs pages still showed FL410. When I tried to change that to FL390 I received the VERT PATH FULL message and speed and altitude disappeared from the legs pages and the message could not be cleared so the FMC was useless. In neither 777 or NGX FCOMs can I find this message. If it is not a message from Boeing , who is it from?

 

I've had that issue before. I had selected and change the STAR one too many times and there were discontinuities all over the place. rebuild the way points and then re-entered the star.

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I've had that issue before. I had selected and change the STAR one too many times and there were discontinuities all over the place. rebuild the way points and then re-entered the star.

I have done that twice in the NGX when I have selected several STARS and arrival runways without clearing discos from previous selections.and received a PROGRAM PIN ERROR message in the FMC quickly followed by the mouse pointer turning to an hourglass followed by a CTD. FCOMv2 explains this as an FMC connector wiring is incorrect, the system is unusable and maintenance  personnel will need to be advised. There are no wires in the NGX and no failures were enabled. A bogus message?

 

Now to the 777. The STAR and runway were never changed. They had been in the FMC for 18 hours on a 21 hour flight. In FSX, SCEL airport has only one runway that being 17/35. Route 1 was to 17 and Route 2 was to 35. The problem appeared when I tried to change the cruise altitude in the FMC from FL410 to FL390 and received VERT PATH FULL which is not a Boeing message on the 777. The message could not be cleared so the FMC was useless.

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It was some time ago for me. You might have some conflicting altitudes. Too many ups in downs in terms of SPD/FL in the legs pages.

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You might have some conflicting altitudes. Too many ups in downs in terms of SPD/FL in the legs pages.

 

 

I am sure you are correct what with the legs pages being changed from FL390 to FL410 when the plane started the step climb and me trying to change it back to FL390 by rolling the altitude down to 39000 and pushing the altitude change knob, The plane descended to FL390 but nothing happened on the legs page. It was still FL410. I then tried to change it using the cruise page to no avail. When I tried to change it using the legs page the FMC became unusable because I could not clear the message I received.

 

However, VERT PATH FULL is not a valid Boeing message. Where did it come from? This not a question directed at you but at anyone who has an answer.

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Its most likely caused by some type of corrupt AIRAC data. Try updating/reinstalling you cycle and see if that helps.

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The FMC Legs page is nothing more than a performance prediction.


The plane descended to FL390 but nothing happened on the legs page. It was still FL410. I then tried to change it using the cruise page to no avail.

This is normal.

You can fly at 10.000ft all day, but the FMC will still asume an optimum flight profile.

You can put 10.000ft in the FMC cruise page, but it will still assume you will climb to a higher more economical altitude, and it will show you that in the Legs page.

This profile (altitudes and speed) is based on CI (or fixed mach speed if entered in the cruise page), weight, wind, etc.

The altitude and speed predictions you see in the Legs page are used by the FMC to calculate ETA and FUEL at Waypoints and destination.

 

When you descend from FL400 to FL390, the FMC will still show FL400 in the legs page, if that is the optimum altitude.

 

Also, if you dont push the Altitude Selector, then the FMC cruise altitude does not get updated, so if you use FLCH for that descend then the Legs page and the Cruise page will stay in FL400 as well, even if FL400 is NOT the optimum altitude.

(the FMC was not told, and still thinks it is in FL400 so to say in that case)

 

There are ways to TELL the FMC that you are NOT going to fly optimum profile though.

The easiest method is by going to the Cruise page and on the left side (LSK 4L) change the STEP altitude.

it will probably say RVSM now.

Change that to 0 (zero) and the FMC will no longer calculate step climbs. As soon as you climb to a higher altitude (using Vnav) the FMC cruise and Legs pages will update to the new FL.

The result is ofcourse that on a long flight the fuel prediction at destination is going to be off by several tons because Step Climbs are not considered.

 

The other (better) method is by leaving the step climb at RVSM (or 1000 or 2000) and instead entering a manual STEP climb on the Legs page. For example if you dont want to climb (or cant due to ATC restrictions) for the next hour or so, you can put the next higher FL some 400nm down the route on the legs page.

Lets say XXXXX is 400nm down the route.

So if you are in FL360, then you legs page should be changed so that it looks like this:

 

XXXXX ............. .83/380S

(speed and slash do not have to be entered, only "380S")

.

This way the FMC fuel and time estimates will be based on FL360 till XXXXX, then a Step climb to FL380 is asumed and thereafter the FMC will put step climbs in the legs page again according optimum profile. (unless you put a STEP size of 0 in the cruise page on LSK 4L again)

 

 

So, long story, but the consence is that you have to tell the FMC what you want it to calculate.

 

Hope this helps.

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 However, VERT PATH FULL is not a valid Boeing message. Where did it come from? This not a question directed at you but at anyone who has an answer.

Tabs from PMDG answered you that in post #3

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The FMC Legs page is nothing more than a performance prediction.

Thanks for  the very useful and helpful information.

 

Tabs from PMDG answered you that in post #3

This had nothing to do with a STAR. The second part I can accept. But still the message is not shown in FCOM1, FCOM2, or FCTM. This is the thread that I consider the best answer concerning the originator of the message. http://forum.avsim.net/topic/363790-vert-path-full/?hl=%2Bvert+%2Bpath+%2Bfull#entry2622736.

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This had nothing to do with a STAR. The second part I can accept. But still the message is not shown in FCOM1, FCOM2, or FCTM.

Yes, but you already said in your post #2 that the message is unique to the PMDG aircraft.

 

So when Tabs responded with "The error means the VNAV solver couldn't calculate a solution for the descent." .....I took that as the confirmation of your own assesment.

 

I have never heard of a Vnav solver on the real 777 so I assumed he meant the "PMDG Vnav solver" caused the problem.

 

And after reading the other threads about this problem it seems There is nothing you can do about it because it is most likely a database error that screws up the PMDG Vnav solver.

 

It does not happen to you all the time does it?

Thanks for the very useful and helpful information.

My pleasure :-)

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It does not happen to you all the time does it?

 

No. Only this one time only. So I am going to forget about. Thanks for your detailed and in depth replies.

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