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Guest amsterdamer

Reset MCP

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Guest amsterdamer

Hi there all, can somebody kindly tell me please what does it mean when Reset MCP altitude flashes up on the FMC message when initial decent into a location just about proceeds and what do I need to do when this message pops up, thanks.Rayek.http://www.precisionmanuals.com/images/for...argo_hauler.gif http://i37.photobucket.com/albums/e62/ritz...tishAirways.jpg http://i37.photobucket.com/albums/e62/ritzer82/untitled.jpg

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Guest Hawkeyeted

Thats your friendly VNAV telling you to set your MCP to a lower altitude so the FMC can let the plane down.

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Guest D17S

The airplane is coming up on its Top of Descent point. But there's a problem this message is allerting you to. The AFS (autoflight system) will not let the airplane descend below the altitude set in the MCP's altitude window. The FMC is saying: "I want to descend soon, but I won't be able to unless you set the MCP to a lower altitude." You're the boss and you have to give the FMC permission to descend. That's what the message is asking: "Permission to descend? Sir!" Once you give it permission (dial down the MCP's aititude setting), the FMC will then descend when its ready.Remember the AFS will never let the airplane descend below the MCP altitude setting in the descent phase. So you gotta keep dialing it down as you go. I generally set it to my ILS approach initial point's altitude. That's where I'm hoping to capture glideslope. But in real life, you'll be getting ATC instructions long before that. So maybe a real world setting would be 10,000 feet initially? . . . just as a reminder that you're gettin' close to the dirt. We've got some real pilots around. Maybe they'd join in with some better advise about real world ops.

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Guest

from what Ive been reading and watching on DVDs, by no means a true expert opinion, is that VNAV descents do not happen often

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Guest Hawkeyeted

>from what Ive been reading and watching on DVDs, by no means>a true expert opinion, is that VNAV descents do not happen>oftenTrue. FAA says that the VNAV is used mostly during the climb, but FLCH is mostly used in the descent. Why? Becuase the FMC is letting the aircraft down, leaving some pilots feeling that they've lost control of the aircraft.

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Ok, I understand that if you're descending using VNAV that the MCP setting acts as a minimum altitude for the FMC. What about during a climb? I think the MCP represents a max altitude rather than a minimum. In other words, if you get a RESET MCP ALTITUDE during a climb, you have to raise rather than lower the MCP setting. So the MCP would set the limit in whichever vertical direction you're going. Am I right?Geoff

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>True. FAA says that the VNAV is used mostly during the climb,>but FLCH is mostly used in the descent. Why? Becuase the FMC>is letting the aircraft down, leaving some pilots feeling that>they've lost control of the aircraft.Really? interesting to know that! ive never descended in FLCH before, have to catch up on that mode :)

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Guest D17S

That's the deal. Except in a climb there will be no FMC alert. If you are climbing in Vnav, the AFS will use VNAV SPD to climb and any limiting MCP altitude will be captured in VNAV ALT. When you finally get to the altitude set in the FMC as your cruise altitude, the AFS will capture it in VNAV PATH. These are all pitch modes and will show up in the right FMA.These modes are really interesting. Now watch how the left FMA (thrust) and the right FMA work together. Watch them "dance" together. What thrust mode is the AFS using for these different pitch modes? Why? What do you think?

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Guest

Sometimes many pilots climb and descend (when not doing it manually) with the vertical speed option. It is easier to control your rate of descent and makes it more smooth on the pax, or precious cargo (I hear horses are loud complainers!)Personally I fly manually with the FD set to VNAV/LNAV up to about 10k or sometimes higher, then set the autopilot to VNAV climb. Get to altitude, and at descent, use flight change by selecting whatever altitude the ATC or I want to descend to.

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Guest D17S

That V/S is another interesting pitch mode, but be careful of it. It has no speed protection. In climb/descent, it will rock the nose up/down to get a vertical rate. Thrust will try to maintain airspeed by going all the way to either stop (EICAS thrust limit for climb or flight idle for descent). But once it's there, thrust has done all it can. V/S pitch mode, with a mindless disregard for speed . . . and your life! . . . will maintain whatever pitch is necessary to get its commanded V/S. In the AFS's (autoflight system) family group, it's the "challenged child." It's really quite stupid.In a V/S climb, the airplane can stall. Actually, the AFS will finally give up on that goofy V/S and swap in FLCH to save the day. In descent, you'll overspeed. Here's how to judge if your commanded V/S is too much. Watch airspeed like hawk. If you start to slow down in a climb or speed up a descent, back off a notch. That said, I heard of RW pilots using V/S for climb anyway . . but (hopefully) they understand the dynamic. In a climb, thrust should NEVER be up against the EICAS limit. Pilots like V/S because a Vnav VNAV SPD climb might provide a very dramatic ROC (rate of climb) and scare the pax. They will set a V/S to a moderate level and watch that thrust stays off the stop. In a V/S climb, thrust at an EICAS limit is a warnihg that you are just about to start slowing down. This is your early warning system. For descent, a VNAV PATH descent is really just a targeted speed on pitch, idle descent . . . (Hey, a calculation based on a fixed thrust + a targeted airspeed = speed on pitch! What can I say?) The FMC will calculate a TOD point on the basis of the following: The FMC will choose a target airspeed. Then, the FMC will use idle thrust to project the path the airplane will take with this idle power settng (i.e., speed on pitch). The FMC will then decide where this descent need to start to get it where it wants to go. This is top of descent. (TOD). At a couple of miles before this point, it will chime and say "Check MCP Altitude." Over you go. As this speed on pitch maneuver stabilizes, it will produce a vertical speed . . ah natural. Try it. Now, here's how you can use V/S in descent to mirror the (short term) performance of a VNAV PATH descent. . . Stabalize in a VNAV PATH descent. Note that you are right on the path deviation center line in your ND. Note your V/S. Now press V/S. The right FMA will shift to V/S. Now watch the path deviation scale. You are staying right on path, but you now have direct control of descending faster or slower as you please. But remember, you will loose PATH if you start playing with it. Actually, after you get blown around a bit, you will loose path anyway. Poor V/S. It isn't very smart.Now that said, Vnav path is much smarter than a simple speed on pitch descent. Rather than using pitch to maintain speed, it will use pitch to adjust the rate of descent (AKA, path). It's doing an

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