cagrikartal

Recycling the Flight Directors

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Thanks Ian, most intriguing, I’m sure there’s something really useful there that I’ve never heard before.I’ll look into it when I’m not so tired as I am now.

You do right, keep your head down !

cheers

Jon Bunting

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Posted (edited)
On 7/11/2018 at 5:10 AM, iwebber said:

I don't think it's Boeing's procedure, I think it's ours

Just checked. It’s standard Boeing fleet procedure I think for circling approach only. Always good to keep abreast other operators procedures, reasoning and philosophies. Looks like air Asiana had fd cycle procedure for npa’s too, meant little to them.

in both air asiana and Air France cases, discipline is key and instrumental. Even now I still wonder why those accidents happened... they didn’t need to and shouldn’t have with a more disciplined crew.

cheers

Edited by Copper.

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On 7/9/2018 at 4:12 PM, cagrikartal said:

I wanted to ask pmdg if is there a fix coming for flight directors. When you recycle the flight directors, you reset the autopilot and annonciator so the directors on PFD  should disappear which is not the case in pmdg 747/737/777. However this is in 737 i presumed it would be the case for the 747 as they share the same philosophy.

 

Going back to the original question in this thread, I am not aware of anything wrong with the way the PMDG B744 Flight Directors are behaving. 

Although Erek is not quite correct in what he says (because both Flight Directors and the Autopilot(s) need to be disengaged at the same time), the procedure he has alluded to is a fairly common one on the real aircraft.  It is used whenever the aircraft is already fully established on an ILS approach and ATC subsequently clears it to land on a parallel runway.

Changing the landing runway after the aircraft is established on an ILS is not an ideal situation to be in, but at places like Los Angeles where it can be very busy with two parallel runways in use for landings at the same time, it is not unusual for ATC to switch aircraft from one runway to the other; especially when they are still a fairly long way from touchdown.    

Provided the aircraft is already coupled on the ILS LOC and G/S, then disconnecting the Autopilot(s) and turning off both Flight Directors is the recommended way to get the AP/FD system out of approach mode.  Only then should you turn the F/Ds back on again before re-engaging an autopilot.  Although it sounds complicated, it only takes a few seconds for the non-handling pilot to change the active runway in the FMS CDU and turn the F/Ds back on, while the handling pilot can either re-engage an autopilot or fly the aircraft manually.  This is usually done using the A/P or F/D in HDG and V/S modes in order to turn the aircraft towards the parallel runway's extended centreline whilst keeping the rate of descent going.  As soon as the new ILS is tuned and identified correctly the LOC and G/S modes can be re-armed and the ILS captured in the normal way so that the approach can continue to a safe landing on the parallel runway..

Bertie Goddard

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Just want to mention that in an Air Canada 777-200LR video, CYYZ-CYVR-YSSY, the captain commands FDs off on final.  From memory, these were ILS approaches.

Mike
 

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On 7/17/2018 at 1:32 PM, Mike777 said:

Just want to mention that in an Air Canada 777-200LR video, CYYZ-CYVR-YSSY, the captain commands FDs off on final.  From memory, these were ILS approaches.

I also remember seeing a video of a Lufthansa Cargo 777-200F that was flying EDDF-RJAA. The First Officer decided to fly the approach with the flight directors off. The Captain chose to leave his on.

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At where I work we also cycle the PM's FD back on after switching both FD off (like on a visual approach or the visual segment of a non-precision IAP), as per what Ian said.

I know that this is a fairly recent change (less than 2 years?). I was told the reason is that in the event of a GA, both FDs would come back on. But upon selection of any subsequent mode, like LNAV at 400ft or VNAV at acceleration altitude, the FDs would now disappear again at a somewhat critical time. So by having the PM's FD on, it would prevent both crew having no FDs.

Hadn't heard about the thrust issues, but it certainly sounds possible. Problem we've had many times is that our sims at work (level-D) aren't always 100% accurate. So sometimes procedures will be validated in the sim only to find out that the airplane behaves differently.  A learning experience all around.

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