Two problems with the 777 - please help if possible

[bluepoole 0]

I have installed the 777-200 SP1 and -300ER expansion, and have the following two problems, maybe someone on here could help me:

 

1. When descending with the 777-200, sometimes (not always) it will stop descending, and try to maintain a random altitude. While doing this the airspeed will drop to dangerous levels...yet in the FMC the speed on the "descend" page ("VNAV" page) will show a realistic value. I have not experienced this effect with the 777-300ER, the latter will fly the same route perfectly and descend normally, and maintain the FMC speed

 

2. For a test flight I've decided to fly Doha OTBD to OMDB...I am selecting OMDB's runway 30L as my arrival, and with the 777-200 and 300, the approach, as indicated by the pink route line drawn by the FMC, looks very weird. It looks perfect with the 737 NGX. I've tested the same route with the 747-400 and that is also not correct. So I guess I have the same problem with the 747.

 

See link to a picture to understand what I mean. I have not yet discovered a similar problem at another airport, but the problem could be present elsewhere as well, I suppose.

 

In all three aircraft, the route page on the FMC shows SEDPO - ILS30L - RWY30L. The legs page shows SEDPO - MODUS - RWY30L. So I feel the programming of the FMC was done correctly. With the NGX, it flies the route and approach perfectly. With the 777's it follows those weird curves and mess up the approach completely. The 747 does not even go to the SEDPO fix!

 

Any help would be appreciated!

 

http://i642.photobucket.com/albums/uu143/bluepoole/402b3b6586a1be2bc7d16732a9fc5ea7_zps58cb740f.jpg

[scandinavian13 5,192]

 

 

1. When descending with the 777-200, sometimes (not always) it will stop descending, and try to maintain a random altitude. While doing this the airspeed will drop to dangerous levels...yet in the FMC the speed on the "descend" page ("VNAV" page) will show a realistic value. I have not experienced this effect with the 777-300ER, the latter will fly the same route perfectly and descend normally, and maintain the FMC speed

 

What does the FMA say when it does this?  The FMA is at the top of your primary flight display (PFD) and displays what autopilot modes the aircraft was operating in (this may be different from what you selected on the MCP).

 

Much more information is necessary.

 

 

 

2. For a test flight I've decided to fly Doha OTBD to OMDB...I am selecting OMDB's runway 30L as my arrival, and with the 777-200 and 300, the approach, as indicated by the pink route line drawn by the FMC, looks very weird. It looks perfect with the 737 NGX. I've tested the same route with the 747-400 and that is also not correct. So I guess I have the same problem with the 747.

 

It looks weird because you're asking it to do something that is not realistic.  There is no way anyone would ask you to fly that kind of path.  Ever.

[bluepoole 0]

With regards to problem 1, I am not sure what the FMA indicated but will continue with testing and if it happens again, will try to record as much detail as possible.

 

With regards to problem 2, I don't know why such strange paths are being generated. I am sure the FMC programming was done correctly. It works with the NGX but not with the 777 or 747

 

I don't even know where to begin with troubleshooting...any suggestions?

[James Bennett 52]

With regards to the image I question how much of that flight you've got correct as you're displaying a master caution with FUEL and FLT/CONT indications. I think you need to go back to basics and learn the aircrafts a bit more.

 

You should never ever be asked to intercept a localiser from an angle greater than about 30 degrees.

[scandinavian13 5,192]

 

 

With regards to problem 1, I am not sure what the FMA indicated but will continue with testing and if it happens again, will try to record as much detail as possible.

 

Be sure to post the results here.  There's not much anyone can go off of without more information on this.

 

 

 

With regards to problem 2, I don't know why such strange paths are being generated. I am sure the FMC programming was done correctly. It works with the NGX but not with the 777 or 747

I don't even know where to begin with troubleshooting...any suggestions?

 

"Problem" 2 isn't a problem.  As James and I have both mentioned, nobody will ever ask you to do what you're asking the plane to do, so there's no need to "troubleshoot" an issue that's not quite an issue.

[bluepoole 0]

Disregard any speeds/altitudes/warnings/cautions...I did not do neat/correct flights, I just loaded the aircraft, "rushed" to the destination with time compression, in order to take the screenshots (did not want to spend a few hours just to take those three pictures)

 

I normally fly correctly and neat, I am quite familiar with programming the FMC, flying on LNAV/VNAV, etc.

 

I have done countless perfect flights with the NGX, including autolands, etc. but even when flying correctly, I experience the problems as described, when flying with the 777.

 

I know you cannot intercept the localiser from greater than 30 degrees.

 

The paths in the pic is what the FMC generates. I basically program (choose) ILS30L as my arrival on the DEP/ARR page of the FMC, I choose OMDB as my destination on the RTE page, and then my legs page shows SEDPO as the first fix, followed by MODUS, and then ILS30L.

 

So with the NGX, coming from Doha OTBD, it goes to SEDPO, at SEDPO it does a 180 degree turn, once the turn is completed and approaching MODUS, I then select LOC, it intercepts the localiser, I then select APP, it catches the glideslope and I autoland perfectly.

 

With the 777, it also goes to SEDPO, but then starts following those weird curves of the pink line, and therefore making it too difficult to intercept the localiser.

 

So my question is, why is the 777 doing that and what steps can one take to solve it?

 

Apologies if I am not expressing myself clearly, English is not my first language.

 

To elaborate more and put it in simple terms:

I do not have an issue with the plane following the pink line, that is what it is supposed to do when flying on LNAV/VNAV mode

 

The issue I have is that the pink line / route is not correct/logical from the SEDPO fix to the runway, when flying in the 777, yet in the NGX it is correct and works perfectly.

[James Bennett 52]

So my question is, why is the 777 doing that and what steps can one take to solve it?

 

Who knows. That is for Boeing to understand. From a pilots perspective you shouldn't be approaching from that angle, regardless of whether other aircraft such as the NGX can technically do it or not. 

 

I strongly suggest setting up different routing or vectoring yourself through a better approach course (i suggest you follow a published arrival STAR or fly a standard traffic pattern).

[bluepoole 0]

OK so if I understand you correctly, you are saying that the route as programmed into the FMC might not be suitable for a heavier, faster, and less maneuverable (compared to the NGX) aircraft such as the 777...with other words the plane is not able to fly it.

 

The NGX is smaller and can fly the route, and that is why it does so without issues?

 

I will follow your suggestion and try the same route but with a STAR at OMDB and see how it goes.

[scandinavian13 5,192]

 

 

The issue I have is that the pink line / route is not correct/logical from the SEDPO fix to the runway, when flying in the 777, yet in the NGX it is correct and works perfectly.

 

Again:

This is because you're asking it to do something it's not meant to do.  The 737 drawing/flying it "neatly" is irrelevant.

 

Solution:

Stop asking it to do unrealistic things.

 

OMDB has STARs.  Those will help you transition from your route to one of the approaches.

[James Bennett 52]

I'm unfamiliar with the airport but I'd assume the published arrivals are set up for big aircraft. Bear in mind just because the FMC allows you to program a certain route that is no indication that the aircraft can fly it. It doesn't take into account the airplanes performance statistics, that is for the pilot to work out.

[Sponge 74]

Yeah, without a proper published arrival, it won't make it.

What was the altitude set on the mcp when it stopped descending?

[bluepoole 0]

Scandinavian13: so you are saying that I am "asking" (or expecting) the 777 to fly to SEDPO and then onwards to runway 30L and coming from the direction of Doha, that is basically too tight an approach for an aircraft the size of a 777?

 

If so, then it connects with what James Bennett is saying.

 

What you all say makes sense...I will then rather use STARs as that way is more realistic anyway at an airport the size of OMDB.

 

As for my other problem, I will do more test flights and if it happens again, I will try and include much more detail.

 

Sponge, I was descending to 2000ft (and 2000ft was dialled in on the MCP), when, at 14000ft, the 777-200 started to go up and down all of a sudden, as if it was trying to maintain 14000ft. The airspeed also dropped so low as to create a warning on EICAS. When I did the same flight with the -300, it did nothing of the kind and descended straight down to 2000ft smoothly.

 

The 777-200 has done it twice now so I am not sure what causes it.

[scandinavian13 5,192]

 

 

Scandinavian13: so you are saying that I am "asking" (or expecting) the 777 to fly to SEDPO and then onwards to runway 30L and coming from the direction of Doha, that is basically too tight an approach for an aircraft the size of a 777?

 

No.  I'm saying it's not appropriate for ANY airplane.  Ever.  This is so much so that regulatory agencies will list "Procedure N/A for arrivals on the ABC Airway," because of the size of the turn required.  Doesn't matter if it's a Cessna or the AN-225.

 

Additionally, you're jumping straight to an approach from your route.  While this occasionally happens, it usually doesn't at airports with STARs (of which OMDB has several).  The STARs (at OMDB) provide a nice transition from your route to an approach.  Using a STAR will provide a realistic situation for your flight.

[pcubine 143]

It looks like you will be arriving from the west so your TP would probably be MIADA. There are four STARS for 30L and 30R - MIADA5R/5S and MIADA4C/4D. The fives are relatively short and the fours are like a sightseeing tour of the desert. When you select the 30L in the FMC the available STARS for 30L will be shown. I don't know which of the STARS 5R/5S and 4C/4D is associated with 30L. The FMC will show you which ones go to 30L. The ones for 30L will end at SEDPO.