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niokilt

command speed bug problem

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hey pmdg, you made a wonderfull add on , it is really fantastic!! however, I have a little problem. I am not an NG pilot, I just hold the type rating and it is start to be old now, so I m not sure if I m right or not,but! during take off, as soon as I rotate the aircraft, the command speed bug goes to v2+20 instead of staying at v2. the mcp's windows speed stil indicates v2 but the bug goes to v2+20. So I tried to simulate an engine failure after v1 but before v2 and I expected to see the command speed bug to stay at v2, but it goes to v2+20. I asked one of my friend who flys for transavia, he told me the last aircraft he flew had the latest fmc's software, 10.8 alpha, and the command speed bug stays at v2 what ever. So I was just wandering if this issue is definitely a bug or not. Thanks for having reading me nicolas jambert


nick jambert

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+1 Already discussed and I have a personal open ticket (still work in progress) with PMDG Support! I hope they solve the issue..... After read, read, and read again the manuals I didn't find any point that specify that Magenta bug into PFD go to V2+20! The only thing is AFTER I engage an A/P mode that remove FD from TO/GA (p225)..... then both MCP speed AND Magenta bug go to V2+20 Before they just mentioned about FD commands at MCP speed +20 (Pitch then commands MCP speed (normally V2) plus 20 knots). Read pages 223, 224 and 225 of FCOM2! So what you state I think is correct! However we will wait for a tech support reply


Roberto Consonni - LIME

 

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The F/D commands:V2 if airspeed is less than V2;Existing speed, if airspeed is between V2 and V2+20; orV2+20 if airspeed is above V2 It's in the Automatic Flight section in my systems handbook. I think the bug still sits at V2+20, but the F/D will make sure your in the correct speed range.


Matt Cee

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Exactly... FD work correctly..... The strange thing is the MAGENTA BUG on ASI (PFD).... However, I'm wait for a tech replay before just to be sure to not saying something wrong. I think PMDG have a really professional and competent staff so they know the 737 and that's is why I'm waiting a replay.


Roberto Consonni - LIME

 

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I really think the command speed should stay at v2, independently of the FD. As I mentioned before if an engine fails after v1 but before v2 the command speed bug should stay at v2 but it goes to v2+20 what ever, but in the sim, the problem is the FD which follows the command speed bug!! so in this case of the engine failure before v2(and the same at v2) the FD tells you to maintain v2+20 while you it should tell you to maintain v2 or the actual speed. so it is definitly a problem..


nick jambert

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VR ENG failure tried this morning.... I have two different situation: 1. Two TO (eng1 / eng2) - VR ENG Fail - At A/C load I set Armed = the Speed bug on PFD stayed at V2 (correct) 2. Two TO (eng1 / eng2) - VR ENG Fail - At A/C load I set Active = the Speed bug on PFD change to V2+20 for few seconds and then back to V2 Please let me know if you and someone else have the same..... p.s: PMDG tech support already informed into my open ticket


Roberto Consonni - LIME

 

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I really think the command speed should stay at v2, independently of the FD. As I mentioned before if an engine fails after v1 but before v2 the command speed bug should stay at v2 but it goes to v2+20 what ever, but in the sim, the problem is the FD which follows the command speed bug!! so in this case of the engine failure before v2(and the same at v2) the FD tells you to maintain v2+20 while you it should tell you to maintain v2 or the actual speed. so it is definitly a problem..
I really think This is the point where you insert facts not opinion.

Randy J Smith

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explain.
FCOM is clear as spin737 stated. That's the fact of what it commands. F/D is also has 'options' for wings level and HDG SEL on T/O.

Randy J Smith

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ok I did several other engine failures after take off and the command speed bug goes to v2+20 and after few secondes it goes to v2 or actual speed or v2+20. so ok, I am sorry for"inserting facts" . but I don't understand why during normal take off it goes to v2+20. cf flight crew training manual "command speed"-"take off": "command speed remains set at v2 until changed by the pilot for acceleration and flap retraction or until a subsequent pitch mode is engaged". So after lift off in the mcp speed windows you have v2 and on the PFD you have v2+20. when you pass acceleration altitude(still flying manually) you set bug up on the mcp and then you realize that the mcp speed windows indicates 20 kts less that the magenta bug on the pfd! tell me if this is normal


nick jambert

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but I don't understand why during normal take off it goes to v2+20 V2 is the min 1 eng out maneuvering speed. It's not the target SPD - that's v2+ 20+ depending although the magenta cursor shows according to - V2 if airspeed is less than V2;Existing speed, if airspeed is between V2 and V2+20; orV2+20 if airspeed is above V2 As the RA and V/S increase, the FD will command pitch to main-tain V2+20, allowing the pilot to transition to the FD. If you're manually flying you're manually flying spds. The MCP window spd is adjusted by you and since you're not engaed in CMD it does nothing but guiding for T/O v2+20. You take off maintaining V2+20 -accel height - retract flap @ speeds and engage modes of choice (Different SOPS will be different here so keep that in mind). Some verify lateral mode @ 500 RA, other can arm VNAV etc prior to T/O. But the point in all this is you fly the aircraft maintaining control via the F/D not a magenta bug or MCP window (although they are set for the F/D guidence).


Randy J Smith

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I know that you fly the FD which brings you to v2+20, and as you said not the magenta bug,so it is not not normal to have this magenta bug on the mcp passing from the value of v2 set on the mcp speed window to v2 +20!!!!this is what I read in the ngx: if my take off profile is v2=150 kts, you put 150 in the mcp speed windows and your magenta bug shows 150kts. during lift off the FD tells you to fly v2+20 170kts then the magenta bug goes to v2+20 as well as the FD commands you, but the speed on the mcp speed windows stays a v2 150. When I pass the acceleration alt, flying manually, I will call for bug up and the pilot monitoring will set manually the magenta bug to the green bug up speed by turning the mcp speed knob. And when the bug is set at bug up you realize that the speed entered in the mcp speed windows indicates 20 kts less than the magenta bug!!!! and bizaarely when you engage the AP the mcp windows displays suddently the bug up speed!! Im going to check this next month in the sim anyway..


nick jambert

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I know that you fly the FD which brings you to v2+20, and as you said not the magenta bug,so it is not not normal to have this magenta bug on the mcp passing from the value of v2 set on the mcp speed window to v2 +20!!!!this is what I read in the ngx: if my take off profile is v2=150 kts, you put 150 in the mcp speed windows and your magenta bug shows 150kts. during lift off the FD tells you to fly v2+20 170kts then the magenta bug goes to v2+20 as well as the FD commands you, but the speed on the mcp speed windows stays a v2 150. When I pass the acceleration alt, flying manually, I will call for bug up and the pilot monitoring will set manually the magenta bug to the green bug up speed by turning the mcp speed knob. And when the bug is set at bug up you realize that the speed entered in the mcp speed windows indicates 20 kts less than the magenta bug!!!! and bizaarely when you engage the AP the mcp windows displays suddently the bug up speed!! Im going to check this next month in the sim anyway..
Are you talking about once you *reset the MCP speed window it should jump to V2+20 matching the magenta cursor? If so then yes it should do that - I'm not sure of anything has changed in that regards in the past few years but I doubt it. What I mean by jump is say you move the knob one click (lets say it's at 154) we move it 155 - it automatically goes to 174 on the MCP.

Randy J Smith

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