NG FMC: Real World Experience?

[Will]

Just curious, anyone flown the 744 with both the standard and NG FMC? Any comments on what parts of the job are noticeably improved (or made more complicated) by the updated technology?

[Hardy Heinlin]

Improved, for example, are a few things on the ND (the map data comes from the FMC):

• Flap speed management during VNAV descent. There are flap points on the ND for flap selections and flap decelerations.

• No open "claws" on the route display. All intercept turns are drawn, also on turns greater than 135°.

• Holding patterns with entry and exit routings are drawn.

• Missed approach legs in dashed cyan.

• ...


FMC handling:

• Automatic SEL SPD settings for flap speeds on descent.

• ...



|-|ardy

[emerydc8]

I haven't flown it, but from everyone I've talked to who has, a big complaint is that you can't increase your descent rate by speed intervening and rolling the MCP speed up. If you do that, the throttles will just move forward. I hear most guys are just bypassing VNAV altogether in that situation and going to FLCH SPD. Everyone says it's great on the descent as long as ATC doesn't ask you to do anything you haven't already loaded into the box.

Jon

[cagarini]

But that's pretty much what I've seen been doing on Airbuses and one of these days on an Embraer 195 too :-)

Pilot's don't like VNAV at all :-)  nor does ATC ....

Will this new NG have that vertical descent profile display too ?

Found this interesting comparison article...

And of course this "Boeing advertisement".  Just hope Hardy makes it less expensive for us PSX users to re-equip our fleet :-)

[Hardy Heinlin]

Will this new NG have that vertical descent profile display too ?

Not on the 747-400.

[cagarini]

Yes, now I recall, it's 748i-specific...

No problem - I've seen it "live" in my cockpit ride on that Embraer 195, and it looks... cartoonish :-)

[Magoo]

I agree with Jon above, you'll end up switching to FLCH as soon as the ATC plan changes... not an improvement there!

[mark744]

I agree with Jon above, you'll end up switching to FLCH as soon as the ATC plan changes... not an improvement there!

Entering the new ATC restriction into the FMC usually works well, as there is flexibility with the On-Thrust VNAV decsent, BUT it sometimes takes ages ( order of 10 to 20 seconds) to compute the new profile and in the meantime rate of descent is a bit random and usually not smooth, so I sometimes use another vertical mode while its recalculating, then back to VNAV. Gets round the problem and then keeps the benefits of a continuous VNAV descent profile.
..Just my experience of NGFMC VNAV

[Hardy Heinlin]

Hi Magoo and Mark,

did you learn from your company courses or sims anything about the MCP SPD window not opening when the VNAV pitch mode changes to the G/S pitch mode while the A/T is disengaged?

On this special subject there's a thread already, but it stopped a few weeks ago:
http://aerowinx.com/board/index.php?topic=4929.0


Regards,

|-|ardy

[Hardy Heinlin]

Another nice new feature in the NG FMC: When you close the MCP SPD window by pushing the round SPD knob while the current FMC command speed is higher than the MCP speed, the FMC will set a SEL SPD equal to your MCP SPD. In the old FMC you have to select your desired lower SEL SPD manually before you close the window, otherwise the speed bug will jump up and your throttles will move forward.


|-|

[cagarini]

Hardy,  just out of curiosity, and because I admire the deep knowledge and enthusiasm you have had, since decades, for this superb airliner, making you probably one of the persons that better understands all of the details of this "special machine", I wonder if along the various investigations you do to "reverse-engineer" the systems of a Boeing 744, and specially those that are directly related to the FMS, and then implement as close to the real thing as possible - not having access to the all of the real data - you sometimes come across stuff that looks like you could actually program / design in a more efficient / logic way ?

If such cases do exist - and I believe Boeing is actually an Aerowinx client ? - do you / would you, forward those observations to their engineers ? 

[Hardy Heinlin]

Vice versa: There are engineers who help me.

[Hardy Heinlin]

As mentioned in another thread, the NG FMC also supports GLS approaches, i.e. RF legs. The old FMC doesn't show GLS approaches on the FMC ARRIVALS pages (I should implement a respective filter in PSX for the old FMC).

However, the 747-400 PFD cannot indicate the IAN features (Integrated Approach Navigation); this would include IAN deviation pointers for a pseudo ILS path and, instead of "LOC" and "G/S" modes, would annunciate "FAC" (Final Approach Course) and "G/P".

So I think the 747-400, when upgraded to the NG FMC, is able to fly RF legs, but possibly isn't certified to do this below the same weather minima as the 748 does with its IAN PFD. I'm not sure.


|-|ardy

[Jeroen Hoppenbrouwers]

If such cases do exist - and I believe Boeing is actually an Aerowinx client ? - do you / would you, forward those observations to their engineers ?

Speaking a bit from "that" side of the world... If people would propose me a "better" way to solve an issue, even if it technically would be better, usually it is commercially or legally prohibitive to make this change. Especially for DAL "B" boxes such as the FMC, changing anything without having a real, tangible, immediate commercial or regulatory benefit would be crazy expensive for nothing.

Aircraft are rarely "tuned" during their life. You get one, maybe two big upgrades with a lot of stuff lumped in, mostly to enable regulatory compliance features and reduce fuel consumption, and that's it. The exceptions are safety-related modifications, usually accompanied by an Airworthiness Directive to spur the operator a bit.


Hoppie

[Will]

Hardy, do you ever fantasize about using your programming skills to design not a replica, but an ideal aircraft?

I'm sure you must have had a few ideas here and there to improve on Mr. Boeing. :-)

[Hardy Heinlin]

No, my fantasy doesn't go that far ... :-)

[mark744]

Hi Magoo and Mark,

did you learn from your company courses or sims anything about the MCP SPD window not opening when the VNAV pitch mode changes to the G/S pitch mode while the A/T is disengaged?

On this special subject there's a thread already, but it stopped a few weeks ago:
http://aerowinx.com/board/index.php?topic=4929.0


Regards,

|-|ardy

FROM AN FMC/ NGFMC DIFFERENCES COMPANY TRAINING DOCUMENT:

7.2. G/S or G/P Capture
(NG FMC) With autopilot and autothrottle engaged and the IAS/MACH window closed or blanked, when G/S or G/P captures, the IAS/MACH window will automatically open and the pilot will set the appropriate speed.
(NG FMC) During manual flight with autothrottle disengaged and the IAS/MACH window closed or blanked, capturing the G/S or G/P will not open the IAS/MACH window since there is no A/T mode active.
(747-400 Legacy) For G/S capture, the 747-400 Legacy FMC operates the same as the NG FMC. The Legacy FMC does not have IAN capability and does not support G/P.


Hardy,
Is this what you were asking?

Regards,
Mark

[Hardy Heinlin]

Yes, that's it, and I just learned from an Atlas Air instructor that this might be a 748 feature and not really related to the 744's NG FMC and old FMC, even though they included it in the text.

If you got this document also from your company on this side of the Atlantic, then I think this is a general Boeing or Honeywell document, and not company specific. That section in the text is vague and nobody seems to understand what it means.

Here's my latest theory of today:

When you cross the VNAV approach glidepath in *manual* flight, the FMC wants to assist you by *not* opening the MCP window because it's possible that you want to fly a circling or a swing-over to another runway etc. and that you, therefore, don't want to descend now. As you want to keep flying level at the current flap/gear configuration, there's no reason to open the window right now.

When you cross the VNAV approach glidepath path in *automatic* flight, the FMC wants to assist you by *opening* the MCP window as it's obvious now that the aircraft starts the descent and that you, therefore, want to set the speed for the final flap/gear configuration.

In this theory I also assume that the "manual flight" condition is just defined by the autopilot status, not by the A/T status. It's just the autopilot that forces the aircraft to descend. The feature probably also works when the A/T is inoperative.


Cheers,

|-|ardy