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Author Topic: ILS sidestep procedure...  (Read 196 times)

jcomm

  • Join date: Dec 2011
  • Location: LPMT
  • Posts: 1594
ILS sidestep procedure...
« on: Fri, 11 Jun 2021 00:14 »
On a given 747 FCOM there's this page:


When the PNF selects both FDs Off, then On, an the AP Off, does the A/T not require re-engagement, and will the FMA show SPD|BLANK|BLANK or all blank ?

Thx
« Last edit: Fri, 11 Jun 2021 00:27 by jcomm »

Jeroen Hoppenbrouwers

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  • Join date: May 2009
  • Location: KTMB
  • Posts: 4197
  • Hoppie designs avionics equipment for airliners.
    • http://www.hoppie.nl/
Re: ILS sidestep procedure...
« Reply #1 on: Fri, 11 Jun 2021 01:35 »

Will

  • Join date: May 2009
  • Location: Chicago
  • Posts: 2208
Re: ILS sidestep procedure...
« Reply #2 on: Fri, 11 Jun 2021 02:42 »
I can't speak to the 747, but we used to do this maneuver frequently into KSTL, my old home base. There used to be LDA approaches to 30L and 12R; the LDA was significantly offset from the runway but parallel to it. You'd intercept the LDA and fly it as a non-precision approach, but as long as you respected the MDA, you could tune the ILS in the second NAV radio for glideslope guidance and treat it as a precision approach. By MDA you'd receive clearance to land, at which time you'd de-select the LDA frequency, tune the ILS frequency, bank to intercept the final approach course while staying on the glideslope, and then finish on an actual ILS. The transition used to happen somewhere between 1000' and 500' AGL, which was as close to barnstorming as it got.
« Last edit: Fri, 11 Jun 2021 02:55 by Will »
Will /Chicago /USA

jcomm

  • Join date: Dec 2011
  • Location: LPMT
  • Posts: 1594
Re: ILS sidestep procedure...
« Reply #3 on: Fri, 11 Jun 2021 11:17 »
Thx for your posts.

Yep AT mode stays !

« Last edit: Fri, 11 Jun 2021 11:27 by jcomm »

Hardy Heinlin

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    • Aerowinx
Re: ILS sidestep procedure...
« Reply #4 on: Fri, 11 Jun 2021 15:10 »
The A/P will be off for just three seconds or so.

Nevertheless, perhaps they just forgot to mention the A/T disconnection. That would make sense because after the "Disconnect" part they wrote "Re-engage the autopilot and autothrottle".