@Jammed Stab
As mentioned in my previous post, flap speeds and manoeuver margins are not to be confused (The FCOM makes it sound like one appears to be based on pilot entry and the other based on (dynamic) sensed information)
@roundsounds
Top of amber bar indicates minimum manoeuvring speed. This airspeed provides:
• 1.3g manoeuvre capability to stick shaker with flaps down
Worded like this, it sounds like a fixed % is added to stick shaker speed which I thought it might be, but an observer reported that the top of the margin remained at the same position on the airspeed tape during manoeuvering whereas the stick shaker speed didn't (unconfirmed).
Stick shaker speed seems to be purely based on non-pilot entry. Inputs to the Stall Warning Cards include:
Pitch angle, body pitch rate, body longitudinal acceleration, body normal acceleration (IRU)
AOA, TAS, Mach, CAS, altitude, Vmo/Mmo discrete (Gear up) (ADCs)
Flap position (FCUs)
Gear position (PSEU)
Speedbrake handle position (the signal oddly goes via the MCP)
The AMM also states that Vbflo (Minimum Buffet Onset Speed) is sent to the SWCs from the FMCs. But what exactly is Vbflo, when is it used by the SWCs and for what purpose?
With the flaps out, the FMC chooses the higher of the two margin values generated by the Left and Right SWC's.