FMC speed restriction

[Guest valterg]

Michael J.I

[Guest valterg]

Hi Michael (BlueDiamond)Please make the test with a lower possible weight, reducing the payload and fuel. The intention is test the speed control capacity of the FMC, eliminating any bias, like weight, wind, etc.Really, when you press LNAV and VNAV is ground, you're only arming these function, not actually turning them on. These functions only will take care of the airpalne after turning on one of the three autopilots (A, B or C), mostly 500 ft AGL.Sometimes, in not so busy days, ATC can let you free to climb up directly to the cruise altitude. Pilots frequently antecipate it, asking to the controller after the departure if it's possible to climb directly, since it shortens the flight time and reduce the fuel consumption.Thanks for making the test.Valter

[Guest Phill]

Please correct me if i am wrong,but you should fill out the speed & REST ,IE."SPD 250 /REST = 10000",see jpg ,as i said i might be wrong?,but that is what i do & i never have speed exceed 250kts.Phill

[macpac22 0]

i generally climb out at v2+10 which in most cases is around 185knots. You can hold this speed for as long as you want by using an altitude setting for your flap retraction i.e 20/3000 but in reality it doesnt make sense to do stay at such a high altitude under 250knots. I would have thought you would burn more fuel and also not help engine wear. As far as ive understood 250knots under 10000ft and in some cases there is no speed restriction just look at the ITVV DVD they were at 300 knots under 10k.If this is just a test flight then fair enough but if it is a real SID then its not geared for a 747-400

[Guest valterg]

Paul,This is a test flight, but the real procedure actually have a leg that must be covered at 190 kt maximum.I deliberately increased for 2 more waypoints the speed restriction, just for test.Please note that, speed restrictions (as well altitudes) occurs in many situations, even if these restrictions they are not written down in the procedures. The FMC MUST follow the speeds and altitudes restrictions that are placed here.Remember that ATC can determine speeds and altitudes for airspace and terminal management, at any time.Valter

[michal 44]

>Remember that ATC can determine speeds and altitudes for>airspace and terminal management, at any time.Yes, they can. It is all well visible on any DVD video (like those from ITVV) that shows typical departure procedures at busy airports. But as such videos also show pilots do **NOT** use VNAV in such cases. They use MCP panels and modify the necessary parameters of flight (speeds, climb rates, altitudes) to accomplish their goals - they not only have far more flexibility this way but also accomplish tasks faster. I suggest you grab one of those videos and see exactly how it is done. It is a very common tendency among 'sim' pilots to over rely on FMC.Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://sales.hifisim.com/pub-download/asv6-banner-beta.jpg

[Guest D17S]

Good observation. That LSK line is certainly also a place where a speed/altitude restriction can be entered. Glad to hear it works. There's another place too.Go to the legs page and look over on the right side. That's where the FMC has calculated what altitudes and speeds will occur at the various waypoints during a climb sequence. If you want though, you can manually enter speeds and altitudes that you want to occur at any of these waypoints individually. That's what we are playing with. We are testing the AFS/FMS to see if it will follow the