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Author Topic: Go-Around procedure question  (Read 330 times)

Will

  • Join date: May 2009
  • Location: Chicago
  • Posts: 2380
Go-Around procedure question
« on: Mon, 17 Jan 2022 17:48 »
Peter, this one might be for you...  :-)

In a certain video tutorial on go-arounds, the recommendation is to achieve acceleration height and then press FL CH and then press SPD, with the side note that the SPD switch will not illuminate (yet).

I've been practicing some go-arounds both with and without pressing the SPD switch, and I can't see the difference. Either way, the mode annunciator on the PFD ends up showing SPD | HDG SEL | ALT and the speed switch illuminates, and the MCP speed is controllable with the speed knob. Why is the recommendation there to press SPD?

Thanks.
« Last edit: Mon, 17 Jan 2022 18:11 by Will »
Will /Chicago /USA

Jeroen Hoppenbrouwers

  • Moderator
  • Join date: May 2009
  • Location: KTMB
  • Posts: 4404
  • Hoppie designs avionics equipment for airliners.
    • http://www.hoppie.nl/
Re: Go-Around procedure question
« Reply #1 on: Mon, 17 Jan 2022 22:43 »
It is to make sure you don't push THR, because that would cause the wings to drop off.

localiser

  • Join date: Aug 2009
  • Posts: 64
Re: Go-Around procedure question
« Reply #2 on: Mon, 17 Jan 2022 22:53 »
Haven’t seen the video, but.. When not using VNAV the normal GA procedure would be to press FLCH and just select the speed you want, and once at the planned speed, to press the THR switch. THR changes the reference thrust limit (in green on EICAS) to CLB or CON after a GA (depending if one engine is inop).

Pressing the speed button as you describe could be a company sop, not everyone does that.

Will

  • Join date: May 2009
  • Location: Chicago
  • Posts: 2380
Re: Go-Around procedure question
« Reply #3 on: Tue, 18 Jan 2022 00:18 »
Thanks, that’s helpful. And the video is the first Go-Around video from BritJet’s tutorials, in the PSX tutorial page.

It would make sense to me that it’s a company SOP, but I’m still unclear on why SPD needs to be pressed.
Will /Chicago /USA

Britjet

  • Join date: Aug 2014
  • Location: Camberley, UK
  • Posts: 1582
Re: Go-Around procedure question
« Reply #4 on: Tue, 18 Jan 2022 09:11 »
My memory is getting hazy now!
I think it was a catch-all in the event that the GA had achieved an Altitude capture before another basic mode was selected. In which case the thrust would not reduce until a flap limit speed was reached - highly inconvenient.

Try a GA without changing any modes until it captures an altitude, and you will see that the speed just runs away.

In any case the FLCH procedure has become secondary to pressing VNAV.

Peter

Will

  • Join date: May 2009
  • Location: Chicago
  • Posts: 2380
Re: Go-Around procedure question
« Reply #5 on: Tue, 18 Jan 2022 13:50 »
Are you saying now that VNAV is the preferred vertical mode to select at acceleration height? This can also lead up to runaway speed unless the missed approach segment or hold has published speed restrictions, or unless the crew speed intervenes, which adds a step because you have to dial the speed right back down to what it was.

I guess the workload ends up being lighter with VNAV as long as you ensure a speed restriction on the missed approach procedure, is that right?

Thanks for your input!
Will /Chicago /USA

Britjet

  • Join date: Aug 2014
  • Location: Camberley, UK
  • Posts: 1582
Re: Go-Around procedure question
« Reply #6 on: Tue, 18 Jan 2022 14:51 »
Yes, I believe that the preferred Boeing procedure is to use VNAV. It came into being quite late in my career and I never cared for it much..
Peter.