A320 Flight Director off on after startup

[MD83FO]

flight directors come ON at FMGC startup.
Is it necessary to turn it off until final alignment and MCDU setup is completed?
and also do so using both hands almost simultaneously to turn it on?
I've noticed this habit.
thanks many

[goeasy]

Different opinions ... Don't think it's an airbus requirement. Current employer always turn them both off after landing. Don't know why. Previous employer - we never touched them unless visual approach etc.

Some people think its a good reset of system. I don't think it's necessary.

Good practice using two hands.... Both off or both on! Guess its why 380/350 only has one button for both FDs.

[Dan Winterland]

IIRC, there was an OEB regarding this topic. It was fixed in our fleet about 5 years ago - may be a function of habit.

[Tiennetti]

Good practice using two hands.... Both off or both on! Guess its why 380/350 only has one button for both FDs.

I am not sure is a good practice :8

DSC-22-30-20 P5/6
Note: If AP/FDs are OFF, and FD2 then FD1 are engaged within 180 ms (one computation cycle),
a flip flop of master FMGC may occur.

[BOAC]

Quite - you don't want to flip flop your master FMGC now, do you?

[A4]

Wow! Does that mean that having lost A/THR channel 1 you could "flip flop" to FMGC 2 as master and regain CAT3B capability? ;)

[320p]

Hi,

I believe some do confuse Both FD's OFF and ON together with doing them simultaneously.It should not be done simultaneously for the reason Tiennetti has mentioned.
However they should be both ON or both OFF together.Has an impact on Auto Thrust modes.One of the reason for A320 accident at Bangalore if I remember correctly.

[MD83FO]

so there really is no need to touch them...

[I-2021]

Wow! Does that mean that having lost A/THR channel 1 you could "flip flop" to FMGC 2 as master and regain CAT3B capability?

A4

You'll get CAT 3 Single as you will have to use AP2 to have A/THR channel 2 as master.

[Check Airman]

Good practice using two hands.... Both off or both on! Guess its why 380/350 only has one button for both FDs.

Now I don't fly an Airbus, and I understand the both on/off principle, but why did Airbus decide to do that?

If the PF decides to hand fly (no AP, A/T), wouldn't it be wise for the PM's FD to be up so he could more effectively monitor the PF's performance?

[MD83FO]

the FD is closely linked to the autothrust logic.
FCOM recommends to follow the flight director exactly no matter which mode its on. then its both ON or both OFF.

[Check Airman]

I understand that, but isn't it possible to have the FMA show:

___ | GS | LOC

In that case, the AT would be off, and the PF would be free to fly and not have to worry about the AT doing something inappropriate?

[I-2021]

Hi Check Airman,

The use of only 1 FD whilst the PF is handflying FD OFF can be quite misleading. You will be most of the time out of the bars as the sensitivity of the machine regarding corrections is obviously much higher than the human's one. I believe that the PNF has already his job in monitoring the parameters regardless of the FD indications. You can't monitor something that the other pilot is not following, i.e. FDs orders.

[Fly3]

Check Airman.
It is not possible to get that FMA because when you switch off both FD's the FMA will show SPEED in the first field.

[737Jock]

Yes it is manual thrust!

[Check Airman]

Thanks guys. Here's a question for you. What if the PF turned off his FD, you'd expect to see

SPD | GS | LOC

What would happen if the A/T was disconnected? Does it matter if the AP is engaged or not?

[MD83FO]

yeah you could fly like that also.

[I-2021]

Hi Check,

you can either be with ATHR on in speed mode (as in your example) or simply OFF. It doesn't really matter. You can be AP ON for the approach and manual thrust if you're not "satisfied with the ATHR performance"

Cheers.

[Check Airman]

Thanks for the information guys.

[heggo48]

All said about the flip flop is correct....you will risk inhibiting the engagement of your A/THR and vertical modes which is confusing and inconvenient and even sometimes hazardous considering that this will happen during flight when you are already under a load and maybe even in a critical phase....
as for the flight director engagement, it should not be done untill the preparation is complete and all the take-off speeds have been inserted because on many occasions, when the FD is engaged prior to inserting the speeds, the managed mode for take off speeds is not considered, and you will not see your speeds on the PFD in magenta, instead you will only see the number 100 in blue, or whatever speed you have selected on the FCU also in blue.......that can only be rectified by toggling your FD off-on again.

[Centaurus]

If the PF decides to hand fly (no AP, A/T), wouldn't it be wise for the PM's FD to be up so he could more effectively monitor the PF's performance

Never having flown an Airbus, so stand to be corrected. But how does having a FD on more effectively monitor the PF's performance? The PFD has a whole host of basic flying information to look at and that is all a competent pilot should need to "monitor." I wouldn't be at all surprised to read in future medical journals that concentrating a pilot's stare on the FD needles has been found to be the cause of old pilots going cross-eyed in their dotage:E

[heggo48]

If you will not use the FD and follow their orders then you should turn them off....because as long as one of them is still on, it directs you to what is set on the FCU, and if you dont follow that then you risk getting what is called FLIGHT MODE REVERSION.....that is a by-product of the flight safety envelopes installed in all the Airbus modern A/C starting from A320....
and its stated clearly in the FLIGHT CREW TRAINING MANUAL :

MODE REVERSIONS
GENERAL
Mode reversions are automatic mode changes that unexpectedly occur, but are designed to ensure coherent AP, FD, and A/THR operations, in conjunction with flight crew input (or when entering a F-PLN discontinuity).
For example, a reversion will occur, when the flight crew:
• Changes the FCU ALT target in specific conditions
• Engages a mode on one axis, that will automatically disengage the associated mode on the other axis
• Manually flies the aircraft with the FD on, but does not follow the FD orders, which leads to the aircraft to the limits of the flight envelope.
Due to the unexpected nature of their occurrence, the FMA should be closely-monitored for mode reversions.

also it has been stated

USE OF THE FD WITHOUT THE AP
When manually flying the aircraft with the FDs on, the FD bars or the FPD symbol provide lateral and vertical orders, in accordance with the active modes that the flight crew selects.
Therefore:
‐ Fly with a centered FD or FPD
‐ If not using FD orders, turn off the FD.

[Chris Scott]

IIRC, in 1988, we used to leave both PBs on, trip both FMGC CBs for 10 seconds, then reset. (Only on the ground.) Are the CBs pilot-accessible these days? ;)

[heggo48]

95% of the A320 CBs are in the cockpit, and accessible to flight crew on the overhead (49VU) and behind the F/O (121VU &122VU)....
Resetting however should only be done according to the "Computer reset Procedures" published in the QUICK REFERENCE HANDBOOK.....some resets are allowed in flight, most are only allowed on ground....
Moreover, some CBs on A320 are monitored by the FLIGHT WARNING COMPUTER and tripping of one of them can generate a caution message that points to the tripped CB.

[Chris Scott]

Thanks heggo48,

No change then! CB cycling was essential to keep 'em flying in the early days, but we soon developed a list of CBs that could be safely cycled (and when), which was later incorporated into the QRH - as you say. I was wondering if the NG a/c might have hidden them (as seems to be the trend on later Airbus types?).

My slight frustration now is that, in all the years since my retirement (from the A320), cockpit visits have been forbidden, even for me in my old airline. So one gradually loses touch. Bit sad when I think of all the people I used to entertain during my career... :mad:

[heggo48]

Well Chris, I have never had the chance of looking at the cockpit of NGs but my guess is that their CB panels are still in place and accessible too, since the Boeing philosophy encourages pilot intervention more than Airbus that is more Biased to Aircraft Automation and system monitoring autonomy, but then again i am not really sure....and i am sure that veteran pilots like yourself had a completely different ball game back then when aircraft were still all conventional, and it took a real pilot to fly, nowadays, all it needs is an operator:)....i started my career as a junior F/O on DC-9 so i can tell how different it must have been back then.....
And yes it is kinda frustrating for people not to be able to see inside the cockpit anymore, especially Former pilots and aviation enthusiasts, and i remember too when it was ok to go inside and take a look or get a photo and chitchat for a while, as my father and 2 uncles were pilots, and as a child i went in there a lot, but not so long after i started my aviation career it became a big NO NO, with all the measures and re-enforced doors, etc.
then again if you consider the security threats we are facing nowadays, it only seems wise to do so......
I guess you can get your glimpse and lot more if you attend one of the aviation EXPOs that are held in many places around the world, they give you Aircraft/cockpit visits for all the A/C on display there.....I had a chance of going into the A380 cockpit in Dubai AVEX 2008.