Good afternoon, In the last few days, after few test on yours excellent 737NGX during take off.... I discovered a strange process during T/O that create a discrepancy between MCP speed and speed BUG on ASI of exactly 20 KTS. As explained into the manual (FCOM 2 - 4.20.13 - Page 223): • MCP IAS/Mach display and airspeed cursor change to V2 + 20 knots but during my takeoffs, only the magenta speed bug on PFD increse of 20 KTS (V2+20), the MCP speed remain at V2. When at "acceleration height" I check the speed in order to increse it to the Flaps UP speed, I discover the A near the flashing speed that was still at V2. Then, once I increased the speed on MCP the magenta bug remainedt 20 Kts over my new selection. Please confirm me if someone else experience this problem and let me know if is my mistake understanding the manual or is really an issue.... Thanks for your coopertion.... and for the excellent product.

Do someone can reproduce it or have a solution?

Good afternoon, In the last few days, after few test on yours excellent 737NGX during take off.... I discovered a strange process during T/O that create a discrepancy between MCP speed and speed BUG on ASI of exactly 20 KTS. As explained into the manual (FCOM 2 - 4.20.13 - Page 223): • MCP IAS/Mach display and airspeed cursor change to V2 + 20 knots but during my takeoffs, only the magenta speed bug on PFD increse of 20 KTS (V2+20), the MCP speed remain at V2. When at "acceleration height" I check the speed in order to increse it to the Flaps UP speed, I discover the A near the flashing speed that was still at V2. Then, once I increased the speed on MCP the magenta bug remainedt 20 Kts over my new selection. Please confirm me if someone else experience this problem and let me know if is my mistake understanding the manual or is really an issue.... Thanks for your coopertion.... and for the excellent product.

You're not following the 'MCP SPD" your following the PFD commanded SPD of V2+20 set from the MCP SPD window. MCP SPD is set to V2. After that you're at accel height and raising flaps etc...

I tryed to give an explanation regarding the discrepancy between my MCP speed and the magenta BUG.... untill I'm force to engage an A/P mode in order to solve the problem. I don't like AP for takeoff and so I left everything off untill cruise or at the end of the SID. The problem in effect is not follow the magenta bug V2+20 the problem is later when I need to set the Bug UP speed or still later that I have a dicrepancy betwwen them. And why is in the manual written MCP speed AND airspeed cursor change to V2+20.... Do I miss something? Thanks

Maybe I'm just misreading this section, but to me it the manual is saying you'll get the MCP display increase to V2 + 20 knots only after the engagement of an autopilot. I could be reading it wrong, but that's how it reads to me. This is straight from the PMDG installed FCOM2. Under the "[Option - Automatic thrust reduction after takeoff, FMC update 10.1 and later]" which is what we have, you get:

flight director engaged status is terminated by engaging an autopilot in CMD (CMD replaces FD in A/P status display)

And indented under that, you get:

pitch engages in LVL CHG and pitch mode FMA is MCP SPD unless another pitch mode has been selectedMCP IAS/Mach display and airspeed cursor change to V2 + 20 knotsroll mode engages in HDG SEL unless another roll mode has been selected.

So.... it is impossible fly manually the airplane whitout FD and AP...... I need to engage AP.... I did MCC on 737 and never happen..... but probably is an option on the 737...... Sorry for my not understanding..... but I'm preparing myself for selection and I would like to understand if it was my mistake.... Really thanks for your quick answer!

If you're manually flying takeoff (of course you are) you set MCP V2 SPD into the MCP window. In the older FMC U.XX software - once you engaged the A/P in CMD the commanded SPD was MCP SPD +20 regardless of the pitch mode. Otherwise we see THR HLD/ N1| LAT MODE YOUR CHOICE| TO/GA | At takeoff with no CMD A/P engaged you should see magenta set to MCP SET SPD ONLY. Once you engage the A/P in CMD (Your choice) you should see the magenta cursor set to + MCP SPD + 20. If you engaged CMD without VNAV you should not have flaps UP SPD displayed on the PFD on the magenta BUG (The flaps 1 SPD) but remaining at the MCP SPD. Of course changes to the FMC software could have changed so we must always double check to see if that is the case.

Really thanks guys for your patience The first two point are exactly what I can see and do..... NO A/P - FMA: THR HLD/ N1| | TO/GA | At acceleration height I call PNF BUG UP speed without any AP command or VNAV or LVL CHG.... the magenta bug is at V2 + 20 and the MCP at V2.... so when my PNF select on the MCP the BUG UP (Speed indicated on PFD ex 220) on my MCP he set 220 but the bug on PFD is at 240.... That's never happend to me.... and why I ask support to you.... Still sorry P.S.: I personally never saw a discrepancy between BUG on PFD and MCP select speed (normally an AP mode as VNAV remove the speed from the box.... but if I see the select speed the magenta bug must match it) Am I wrong?

Please anyone from "Tech Team" could answer to my last post.... Thanks

hmm i must be a clown as i also find it difficult to understand. Normally with other 737 i have FD/on , AT/on, TO/GA/on and V2 for instance 154 in MCP. After takeoff and hitting A/P at 400 feet or later should i get 174knots in PDF AND the MCP ? It still gives me 154 in both and A154 in the MCP Michael

Roberto,Let me see if I'm understanding correctly:You're saying that at acceleration height the MCP speed window and the PFD speed bug should be synchronized even if you're still in TO/GA mode? All the documentation we have shows TO/GA pitch mode command speed being MCP+20 until you engage another pitch mode. Very easy to change but we need confirmation that the NGX is actually wrong - one of our tech advisiors is pretty sure the MCP on his company's airplanes does not sync with the bug until you exit TO/GA mode, but he's not back to work to check for sure until next week.

hitting A/P at 400 feet or later should i get 174knots in PDF AND the MCP ? Michael

Why would the MCP SPD window change? The MCP window is manually set to V2. It is not set to V2+20 nor does it change to that.

Why would the MCP SPD window change? The MCP window is manually set to V2. It is not set to V2+20 nor does it change to that.

Ok the MCP window will change to +20V2 under these conditions - You manually adjust the mcp spd knob and (one click will make it jump)You engage the A/P in cmd from TO/GA.

I've studied with FOMs and it's quite enlightening!!Especially learned so many procedures for takeoff..I used to be a LNAV/VNAV guy.. Eh.. so, back to the topic, I found this.. the of Year 1993.http://www.pprune.or...gs-v2-20-a.htmlSeems correct PFD bug is different with MCP. (if this post is also correct one, too)

I posted in another thread that got buried I guess that with the newest hot-fix 15AUG the magenta bug now does not jump to V2+20 but stays at V2 unless you have VNAV armed. Is this now the correct behavior on takeoff?