Landing Vref bug question

[Guest Erups]

When i setup the entire flight trough FMC, on landing i have a nice white bug on the speed tape together with a green one.But none of them is ever in the indicated speed.I mean if i have a certain vref, say 137kts, and add 8kts wind correction, i have a final vref of 145kts.Well neigther of the bugs do ever point to 145, nor 137 for the sake of it...So i am asking if there are some internal calculations i do not know of, or what?

[Mats_J 2]

Hi>So i am asking if there are some internal calculations i do not know >of, or what?YEs. I would certainly think this is the case. You'd be amazed if you knew what takes place inside this sim.The white bug on approach is the bug for the flaps 15 speed (I'm sure it has some fancy V-abbreviation as well). Useful for GAs.Also you should have a couple of green bugs. Some are speed bugs for the next flap setting and finally you have a Vref bug which should be at the Vref speed in the FMC.Hope it helps,

[zubart 5]

The white speed bug you are refering to is called the "VREF+15 Bug" and is displayed after selection of VREF. It's automaticlly set 15 knots above VREF. On a single engine go-around VREF+15 is approximately equal to V2 for flaps 1.On a engine failure on final approach VREF+15 is equal to at least VREF for flaps 15.Set the magenta command speed bug (MCP airspeed window) to VREF + wind correction always.Floyd

[Guest mangold]

Guten Tag gentlemen.PMDG 737-600/700 The following 2 excerpts of FMC Users Manual cover the issue. For 'take-off' FMC "...control the speed bugs on the Primary Flight Display"For 'landing' the manual says NOTHING about FMC speed bug control.Q:does FMC set speed bugs for landing correctly or not ?Regards, G

[Qavion 19]

"V1/Vr/V2: The Next Generation 737 does not automatically populate the FMC with V-Speeds based on crew input to the FMC/CDU. V-Speeds are normally entered manually into the TAKEOFF REF page to control the speed bugs on the Primary Flight Display."This is not entirely true. The Bulfer FMC Guide mentions an option which will allow this. Suggested speeds are generated after crew initialization data entry. These appear as small font speeds in the centre of the CDU display. Pushing the right line select keys adjacent to the speeds twice will transfer the speeds to the PFD."Q: does FMC set speed bugs for landing correctly or not ?"They should do. Are you not getting them... or getting them in the wrong spots? For A/T control, it's normal, of course, to manually set the command airspeed bug via the MCP to match the FMC-computed value.Cheers.Ian.

[Guest Erups]

I am getting two bugs:one whiteone greenand the usual magenta oneMy problems where with the white and green, because they did not point to any of the speeds selected in the mcp.Now thanks to the messages to this post i am going to have a check on it.