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clayton4115

flying through FMC programmed waypoints

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hi all did a flight from YBBN to YBCS last night and my first waypoint after departing Brisbane the airplane went past the waypoint and continued on its merry way straight ahead, i had to intervene so the 777 would change course and track its new intercept heading this happened on 2 occasions the other while coming into land into Cairns where it missed another intersection.Also ive noticed while flying very light, the plane seems to overspeed while climbing and i get this annoying overspeed warning, so obviously the air file is not tweaked properly.I just can't believe these things are still evident after a comprehensive patch and i am quite dissapointed that quality of this product has been undermined from such a good company.p.s i must give pss big marks for the frame rate friendliness of this AC but still there are blaring issues outstanding on this product.

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Hello Clayton,With regard to the comment "...Also ive noticed while flying very light, the plane seems to overspeed while climbing and i get this annoying overspeed warning, so obviously the air file is not tweaked properly..." Have you derated the engines? With a light load you need to bring the the power back to the lowest rating possible. (Just in case you missed it elsewhere). The engines on these planes are just so powerful, hopefully PIA or someone will start flying them into Brisbane soon and we can get a good look at them ourselves.To your other issue, can you give me the departure and arrival procedures that you used, and I will try it tonight.regards,

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hi Stevenno i havent derated the engines, if thats the situation i withdraw my comment, will try derated takeoff sometime soon.

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What pitch mode were you climbing in? Was the autothrottle engaged? Try your climb again with the AT engaged. Also, use either Vnav or FLCH for your pitch mode. Both Vnav and FLCH are

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777 Flight Crew Training ManualClimb, Cruise, Descent and Holding Chapter 44. Climb, Cruise, Descent and Holding-Climb, Cruise and DescentPrefaceThis chapter outlines recommended operating practices and techniques used during climb, cruise, descent and holding. Loss of an engine during climb or cruise and engine inoperative cruise/driftdown is also addressed. The recommended operating practices and techniquesdiscussed in this chapter improve crew coordination, enhance safety, and provide a basis for standardization.ClimbReduced Thrust ClimbEngine service life may be extended by operating the engines at less than full climb rated thrust.The FMC provides two reduced thrust climb selections on the THRUST LIMIT page:- CLB 1 is a constant 10% derate of climb thrust- CLB 2 is a constant 20% derate of climb thrustReduced thrust climb may also be automatically selected by the FMC depending upon the amount of thrust reduction made for takeoff by either the fixed derate or assumed temperature method.Climb thrust reductions are gradually removed as the airplane climbs until full climb thrust is restored. If rate of climb should drop below approximately 500 feet per minute, the next higher climb rating should be selected.Prior to takeoff, the pilot may override the automatic reduction after the takeoff selection has been completed by selecting another option on the THRUST LIMIT page.Note: Use of reduced thrust for climb increases total trip fuel and should be evaluated by each operator.Climb ConstraintsClimb constraints may be automatically entered in the route when selecting a procedure, or manually entered through CDU entry. When the airplane levels off at an MCP altitude, that altitude is treated as a climb constraint by the FMC.All hard altitude climb restrictions should be set in the MCP altitude window including

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Me too. I almost always use the AP. It does a much better job than I can. Although, I'm working hard to perfect (. . . heck, just to keep from crashing) a hand flown, zero visibility flight directed approach to landing. Whaoh doggies, that's tough!If the AP was engaged in Vnav pitch mode for a climb, the pitch mode would have been "VNAV SPD" and its thrust partner would have been "THR REF" (to TO thrust). So "THR REF" / "VNAV SPD" would have annunciated in the left and right FMAs. The MCP airspeed window would have been blank. Thrust would have been up to the EICAS thrust limit and pitch would have been controlling airspeed to the magenta number above the speed tape. You had these modes in the left and right FMAs? Pitch will rock the airplane back to whatever deck angle it takes to control airspeed . . . right up to the rake. I have heard of 747-400s needing 27 degrees of pitch to control airspeed. The point is that in VNAV SPD, the airplane will not over speed unless there is something wrong with the model. If a de-rate keeps the airplane from overspeeding in VNAV SPD or FLCH SPD, it's not pilot error! You're doing fine. On that Lnav issue, make sure that wasn

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Brianyour article doesnt say anything that the captain should use derate of climb thrust when the plane is light and thinking about it nowthe FMC 'computer' should work out appropriate speeds even if there is full power applied to climbout when the plane is light, so i dont see why i should use a derated climb in the 777 PSS when this would not occur in real life (getting speed warnings on climbout at full power), thereby i still think the air file needs to be worked on.

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Steveni used the Coral2 departure on runway 01 and the Baria arrival into Cairns for 15.

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"so i dont see why i should use a derated climb in the 777 PSS when this would not occur in real life (getting speed warnings on climbout at full power), thereby i still think the air file needs to be worked on."Clayton,There is absolutely nothing in the airfile on any aircraft which is going to prevent overspeed with a lighter loaded flight if you use the same thrust as with heavier loads. That would be like saying "I purchased a sports car and there is something wrong with it as everytime I put my foot down hard on the accelerator pedal the car goes too fast and won't stop"!Please understand that the airfile is responsible for the predictable behaviour of an aircraft in response to either pilot commands or autopilot commands. In the PSS 777 ALL autopilot functions are programmed by custom gauges and are entirely seperate from the airfile. If you set high thrust on a lightly loaded 777 then unless you climb sufficiently to let gravity counteract the thrust then inevitably it is going to overspeed. How could it not? There WOULD be something wrong with the airfile if you did NOT get overspeed with full climb thrust and a light load and did not manage the climb.If you have an issue with the way the autopilot manages climb then that is another matter, but looking at the knowledgable responses here it seems that the culprit is (and you confirm this in your posts) that you are not using de-rated thrust. If you look at the thrust/speed/load tables in the supplied PDF's they make it very clear that as your loadings decrease so do the recommended thrust settings for both take off and climb. The thrust values decrease VERY significantly the lighter the load.If you are very light indeed then it is to my mind understandable that the FMC is going to be stretched though it is doing its best to cope with what are essentially your own commands. Even though there might be some flaws in this, it is you the pilot who is responsible for managing the aircraft. Even the best autopilots cannot stop a pilot from forcing an aircraft to overspeed.Please do not keep blaming the airfile everytime you encounter an issue which you are not absolutely sure about. If you are unhappy about the way the aircraft flies manually or handling issues then I am happy to look at any comments you might have.Kind Regards,Rob Young

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ok thanks Rob, if thats what they do in the real world, use derated thrust when the AC is light, thats what i will do as well and report my observations here.rgds

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Hey Clayton, "so i dont see why i should use a derated climb in the 777 PSS when this would not occur in real life (getting speed warnings on climbout at full power), thereby i still think the air file needs to be worked on."Me too, but just to clarify: After the auto-throttle is engaged in "THR REF" and the autopilot is engaged VNAV SPD or TOGA pitch mode, airspeed continues to increase. It continues to increase all the way into the red airspeed overspeed bricks . . . with all corresponding airspeed warning racket. Right?I don't know what an "airfile" is or how it might affect anything, but if this is happening, it should NOT be happening. Derate or not.I once watched an empty 757 takeoff at max TO thrust. It was a management crew on their way to do flybys at an airshow. The nose pitched to at least 30 degrees and the airplane climbed at 45 degrees. It was like a daw-gown F-16. Amazing. You can control as much thrust as the airplane has by just pitching up, further and further. But you can't be afraid of it. You have to get that nose up. Here's a test flight for ya.Get light and try a handflown, full power TO. Make a note of your FMC's computed V2 speed. Set TO power then take your hand off the throttle. Do NOT touch it again. Leave that hand in your lap. V1 and VR will be right on top of each other, so rotate EARLY. Now here's the trick. Rotate positively and get airborn. You want the tail clear. Watch radio altitude to about 50 feet . . . then just forget the command bars. Don't mess with gear or flaps for this first test flight. (Once you see what's happening for the next try, get the gear up.) At 50 feet RA, LOCK your attention onto the airspeed tape. Now PULL! Stop messing around, dag-nabit. PULL! Watch the airspeed tape and just keep pulling until you stop the acceleration. Just keep pulling until the acceleratin stops. Pull! Watch out for the yellow max AOA rake above the FD bars. That's your pitch limit. But just glance there. Fly the airspeed tape. Fly the speed tape. Pull until you stop accelerating. Get it done quick. Fly the speed tape.Now stabilize at that speed. Hold it there. What's your rate of climb? It's what?? Wow! Keep holding it there. Take a breath. You are stable. You are in a speed on pitch climb. Keep holding that airspeed with pitch. Now pull some more to get slowed back down to V2. Stabilize. Rate of climb actually increased? Holy ROC, Batman. Now nudge forward to get V2+10. Stabilize. Now pull back again to slow to V2. Control speed with pitch. You are flying a rocket ship. Don't detrate nothin'. This is

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hi thanks for that however im about to depart KJFK to Heathrow so i will try your test some other time, i will departing with a derated take off, let see how it goes.

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