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dogs53

Green Arc

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I have been flying the PMDG 737 and 747, and am wondering if someone can explain the green arc moving through the second display from the on the cockpit view. I seem to always get it after take off. And, I get it at other times also. It starts at the top of the display, comes part of the way down, and then goes back up. I am sure that it is telling me something, but I don't know what. I have looked in the manual and can't seem to locate any information on it.Thanks

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You're probably seeing the arc that the FMC constantly calculates and displays predicting when the next altitude setting will be reached based on airspeed and pitch. Change your airspeed or pitch and the arc will move to show the change in distance required to reach the next altitude way point you have set in the FMC. Very helpful for monitoring descents.Kim


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As you may or may not know the ND serves as a situational display to the pilot. With that said, when you change the altitude on the MCP and the aircraft starts to climb or descend the Green Arc is a point along the route at which the plane will reach the targeted altitude.As you gain more experience flying the 737/747 you can use the Green Arc to your advantage. As Kim said, its very usefull on the descent phase of flight and during non-presision approaches.


Kevin Hester,

 

Indianapolis, Indiana

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Thanks.. makes sense.. I guess it is changing based upon the climb/descent that FMC is projecting. I pretty much fly on VNAV, so that is probably why it is changing..Tks

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Yes it does change frequently. It changes based on the Pitch attitude of the aircraft and the MCP altitude. Any climb/descend mode youre in youll see the Arc.


Kevin Hester,

 

Indianapolis, Indiana

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>Thanks.. makes sense.. I guess it is changing based upon the>climb/descent that FMC is projecting. I pretty much fly on>VNAV, so that is probably why it is changing..>>TksIt's way more powerful than that - it allows you to very easily do manual descents using V/S mode for instance. Say ATC tells you to cross a waypoint at a certain altitude - just set the MCP altitude to it, then roll down the V/S wheel until the green arc hits the waypoint - that's the rate of descent you need to reach it. You can use VNAV to do it too, but often times in a busy terminal environment where ATC is giving you a bunch of vectors, you're watching for traffic etc there's just not the time luxury of being able to program the crossing point in, especially if it's not a point already on the flightplan. It's much easier to say, create a 40nm ring around the airport on the FIX page and put the green arc on it manually than it is to create an along track waypoint, set the restriction etc...


Ryan Maziarz
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Dogs53:Please sign all posts with your real name.The arc is very useful for instance when ATC says, "Speedbird 0225, decend at pilots discretion to FL150, 15 miles prior to TIGER." Obviously this is manageable in VNAV (and I enjoy enroute mods as much as anyone) but in a dense ATC environment, where being heads up might be a priority, just popping in the FIX TIGER with a (/15) circle around it would then allow you to set 15000 in the MCP ALT, go into VS and twiddle the knob. When the green arc just intersects the circle you will be decending at the correct VS to be at FL150 15 miles before TIGER. Adjust, wait for a moment for the FMC to recalculate and then re-adjust. Constant scrolling back and forth doesn't allow the FMC time to correctly forecast.She's a grand girl- enjoy!Best-Carl F. Avari-Cooper BAW0225http://online.vatsimindicators.net/980091/523.png| XP Pro SP3 with FS-GS System Unification | 2 x APC UPS | Coolermaster Stacker 830 SE | Asus P5E-Deluxe (X48) | e8500 @ 4gHz | Tuniq Tower 120 | EVGA 8800GT 512MB | Sony 40" Bravia XBR | 2 x 1 GB Corsair XMS2 | 500GB Seagate Barracuda 32MB SATA2 | Corsair HX620W PS | CH Products Yoke-Pedals-Throttle Quadrant | Aerosoft 747MCP-EFIS-EICAS |


Best-

Carl Avari-Cooper

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I found flying on Vatsim really brought the aircraft to life for me. Flying in such a dynamic environment makes you appreciate how powerfull the various tools at your disposal are.Rob


Rob Prest

 

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