What are the problems with FDs?
One of the Golden Rules is "one FD off, then sw both off"
and . ."using one on, then both on" Another SOP as determined by a TCAS RA, includes, FD off . . . .(and the rest of the RA procedure, using the v/s green band . . etc. . .) Specifically, my question is: As there have been some `watch out` references to the FD by some well seasoned and experienced pilots on here - what lies therein? What is the supposed dodgyness of FDs if any, apart from those I mentioned above? Thank you for your time. |
One of the Golden Rules is "one FD off, then sw both off" MY only golden FD rule is... look through the bloody things! :} |
look through the bloody things . . ? . . . .to the artificial horizon beyond . . ?
(and the alt and the spd and all the rest of it?) |
Airbus TCAS
1-) This is not named as one of "Golden Rules" but "Memory Items" in Airbus terminology.
2-)Both FDs are turned of at the same time. 3-) The reason is : From Airbus FCTM : - Both FDs must be disconnected once APs are disconnected: ‐ To ensure autothrust speed mode ‐ To avoid possible confusion between FD bar orders and, TCAS aural and VSI orders. |
I have never needed to turn off the FDs when disengaging the AP. There's no reason you can't hand-fly the bars.
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look through the bloody things . . ? . . . .to the artificial horizon beyond . . ? |
It's not a golden rule, but it is Airbus SOP for the reasons listed above. It's not that the FDs are a problem, it's the interaction with the autothrust.
FDs should be off whenever you aren't going to follow them. Examples include TCAS RAs, visual approaches, NPAs once you are below MDA, and hand flown departure procedures with no coding in the FMS. |
The reason for
It is just a "common" rule. Clear up what you do not use. It is like the LS bars. You only select them on if you are gonna use them, no? Besides it clears all your previous selected modes and clears the FMA. |
Effing Dee's
Actually Nats, there really isn't a 'problem' with the FD's (or at least, that was not the message being conveyed in that Golden Rule).
From what I understand, Airbus insists that whatever you do to one FD, you do to the other. That's pretty simple and also obvious. If you need to switch off the FD's (for example, TCAS RA), then switch BOTH FD's off, not just the ones on the PF side. A lot of guys will tell you that FDs in general are flakey and stupid, etc.; but that's another discussion. :) |
Originally Posted by ahramin
and hand flown departure procedures with no coding in the FMS.
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what is wrong with raw data and hdg sel or is that forbidden in your airline? In the early days of EFIS, what became the jocular remark of "I can't fly - but I can type at 80 WPM," is now truer than ever before. Even the selection of HDG mode is seen as a 'downgrading' of automation. The combination of raw data and HDG SEL now sends shivers of alarm among even experienced pilots let alone the newbi seconds-in-command with their new MPL licence. |
Natstrackalpha
In early 90s during a non precision approach there has been a fatal accident They were in open descent mode, difficult to say why. Then only no.1FD was switched off leaving the other on, as a result ATHR did not change to speed mode. FWB was a very new concept then, also the crew was inexperienced. They took time before deciding to go around. The a/c hit the ground as engines were spooling up. Since then this practice of announcing FDs off and switching both has been reccommended and followed. But it is not included in the Golden Rules. |
After a few sectors with new F/O’s, F/Ds off and A/T off below RVSM. Some of our shorter sectors never make it above FL260. All briefs at the departure point and hand flying from takeoff to touchdown, without F/Ds. New F/O’s need to be reminded that F/Ds provide guidance information only. The command bars are always darting about the PFDs. The new F/O's are forever chasing the pitch and roll bars in an endless game as if trying to tame those rogue bars.
I de-select one mode at a time, pitch off, then on, then roll off then on. This starts the scan process going, then eventually both modes off. The grin on their faces appears when they discover how smooth they handle th ejet without command bars to chase about the PFD. I don't permit the use of the FPV either. If weather permits, raw data and visual approaches are accomplished too. What it comes down to is that we as trainers need to re-acquainting new F/O’sto the 4 fundamentals of flight. Manual flying leads to manual descent planning calculations to get away from their total reliance of the FMC. But that’s a topic for another thread. |
I feel the reason to switch off the FD bars is basically when the pilot is not following the FD commands. This can happen at time of TCAS or any other event.
Both FD are switched off to avoid confusion. |
Originally Posted by Centaurus
The world wide problem
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Hi Guys
The question Nats has asked is why the FDs are switched off together and put on together. Indeed there is such procedure and it is insisted upon in Airbus. The merits of flying manually with FD etc is different topic altogether. One of the conclusions of the inquiry of the accident was, had the other FD been switched off the ATHR would have changed to speed mode. What Ahramin stated in reply no. 8 is correct. It is because of the interaction with ATHR FDs must be on or off together. |
I feel the reason to switch off the FD bars is basically when the pilot is not following the FD commands. This can happen at time of TCAS or any other event. Both FD are switched off to avoid confusion. From Airbus FCTM : - Both FDs must be disconnected once APs are disconnected: ‐ To ensure autothrust speed mode ‐ To avoid possible confusion between FD bar orders and, TCAS aural and VSI orders. The reason is, if you are in open descent and disconnect the AP and pull back for a TCAS RA no thrust will increase, your speed will bleed off and you wont climb very far. Turning off both FDs puts the autothrust into speed mode so as you pull back the thrust will increase. |
Depending on the operator SOP and aircraft type, it may not be true to require both FDs off. Not talking Airbus here, OK?
e.g. an aircraft with a single FD input but dual displays - makes sense for the PF to take-off, say, in GA mode, while PNF stays on raw data. Both FDs on at safe altitude. On approach, PF uses the modes required, PNF monitors in raw data. Reason being that a spurious FD command may be more readily noticed by the monitoring pilot detecting the flight path deviation. Also 'looking through" the FD is too hard for this old-timer, though some seem to be able to do it. Unless following the FD commands, it goes OFF. Raw data is actually easier in some situations. |
Children of the Magenta?
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I have just had sim with grand pa of the magenta line...very scary indeed.
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