I'm sorry guys, but you 'bush lawyers' are half the reason there is so much confusion with what is required & what is not!
It was
"The command speed bug is set to the target speed you will be flying on the approach for both manual flying & with the autopilot engaged. So you set the speed you want to maintain - in your 1st example, 138kts"
which contradicts the Boeing 'advice' and indeed highlights the dilemma that advice is known to cause.
seems to be the problem here but frankly, it's not that difficult! And what exactly is it about my statement that
contradicts the Boeing 'advice'?
Let me put it as simply as I can -
*The 'target approach speed' for autothrottle engaged is Vref +5.
*The 'target approach speed' for manual thrust is Vref + wind correction, with a minium correction of 5kts & a maximum of 20kts.
*The command speed bug is set to the 'target approach speed' on both autothrottle engaged approaches & for manual thrust approaches.
*If you disconnect the autothrottle during an approach, you should technically reset the command bug speed to Vref + wind additives.
'Target approach speed' is my term & I have used it to refer to the speed you have calculated that the approach should be flown at, either Vref +5 for autothrottle engaged approaches or Vref + wind additives for manual thrust approaches.
As for -
I NEVER bug Vref+5 with autothrottle in anything above a 'zephyr day' since the sometimes wild attempts by the a/t to maintain its 'programmed' margin are often too much to tolerate (for a sensitive soul like me).
This is outside the recommendations of the FCTM.
However, I do agree that the speed keeping ability of the autothrottle & sometimes large thrust lever movement can leave a lot to be desired. You may prefer to go outside the FCTM recommendations in order to deal with this issue, but I prefer to set the command speed bug as per the FCTM & simply over-ride the autothrottle manually when required.