A330 PFD Indiatication
 

Pilots, can anyone kindly explain to me how would we know whether the system is in ALTN1 or ALTN2, just by looking at the PFD?:8

Thank you goeasy!

The FCOM does mention ALTN1/2 though! It doesn't matter, I guess!

You can't tell by just looking at the PFD, but it depends on the severity of the failure, in some cases you keep ALT 1 with a few more protections then when you end up in ALT2.

FCOM 27-20-20 Alternate Law explains it.

Thanks very much, PGA! I will look it up.

Basically you cannot tell if you are in ALT 1 or 2 BUT IN ALT 1 you have AOB protection

No you cannot see on PFD. Also it shouldn't matter because you should not be flying outside the flight envelope to need it. However not having herd in years of flying Bus is scary because there may be many other thing that you haven't herd of.

Yes the PFD does show the difference.

In ALTN 1 you can loop the Jet ( in theory!! ) with no pitch limit protections and as such the double green protection symbols are not on the pitch scale, replaced with yellow x

In ALTN 2 you can loop and roll the Jet, as such the double green protection symbols are not there at 67 deg aob or 30 pitch up and 15 down, replaced with yellow x

So, The PFD enhances the situational awareness of the status of the flight controls and you can see which protections are lost by simply looking at the specific symbols ( =green )


Easy.

All in your FCTM

Sorry I was talking about A320.

ACMS:

Speaking specifically about the A330, FCOM DSC-27-20-20-10 note (4) says that

"Bank angle limitation remains effective in ALT 1, which uses roll normal.
However, since ALT 1 is generally an unprotected law, all protection marks on the PFD are in amber for simplicity."

Even in ALT1 the amber marks for the Angle of Bank protection on the PFD will be amber, even though Angle of Bank protection is still available.

Thus as far as I know, there is no way to discern from the PFD whether you are in ALT1 or ALT2.

My quote regarding using the symbols on the PFD to see which protections are lost are straight from the A330 FCTM.....

I do recall seeing just that in the SIM but it was a while ago.

It wouldn't be like an Airbus FCOM to be misleading now would it !!

Looking in the FCTM, OP-020, Indications section says the following:

"When protections are lost, amber crosses (X) appear, instead of the green protection symbols (=)."

The picture below it then shows the PFD in 3 configurations, Normal Law, Alternate Law and Direct Law. In the alternate law picture all of the protection symbols are replaced with amber crosses including the Angle of Bank protection indicators. It does not differentiate between ALT 1 or ALT 2.

If the airplane is in alternate law, ALL off the protection symbols are amber, regardless of whether the A of B protection is lost.

The FCTM does seem to agree with the FCOM in this case, although admittedly it is not quite as specific.

FCOM: "Bank angle limitation remains effective in ALT 1, which uses roll normal.
However, since ALT 1 is generally an unprotected law, all protection marks on the PFD are in amber for simplicity."

From both the FCOM and the FCTM I understand the following: You will never have some amber crosses and some green protection symbols. It is all or none. And thus you will not be able to tell if you are in ALT 1 or ALT 2 by looking at the PFD.

Wow indeed. I wonder who did your type rating tech, and are you saying that you have never read the books?

Is there any practical use of knowing difference between ALT1 and ALT2? How would you use this wonderful knowlegde?
You get your rating after CBT, FTD, and FFS. Few weeks. You don't have time to read all 10 kg of FCOM. Reading and deeper undestanding comes later.

Thank you very much everyone! Very useful understanding of the system and associated display. (I did learn what I expected to learn).

The manufacturer has provided it with some purpose. Ignorance of flight control system in FBW is not good. In alternate 1 with manual thrust if you happen to drop speed the aircraft will pitch down below VLs while in Alt2 it will keep loosing speed and keep trimming all the way to stall. In A330 In roll there is protection in Alt1 but not in Alternate 2. The worst thing if someone didn't bother to read in years and this professionalism then why waste time asking any thing on PPRUNE? Better to enjoy a movie.

Uplinker and Vilas, you are correct.

I hope he is not really a pilot.

Dreadful.

These are the last things you will be thinking about when you are in trouble that led to ALT Law. Just fly the aircraft.

Lack of knowledge of alternate law in flight control system is dangerous. It is shocking that year after year he can be cleared in tech refreshers. If you think ignorance makes you a better pilot then I can only wish you good luck.

vilas, I completely agree :ok:

Wow again.

The point is, Romasik, if a so-called pilot has "never heard of ALT1/ALT2 law", then it shows that they have never read the books, that is the shocking thing here.

With a FBW, (or in fact any) aircraft, understanding - or at least knowing about - control reversions in the event of failures is a very fundamental thing.

How much else about the aircraft does this person not know about. How did s/he pass their type rating?

:mad:

I know what ALT law and it's variations are and refresh this and many other things every time before the simulator as it's always preceeded by quite a serious oral. And I have to admit that I never think about it during the simulator session. Whatever situation is. I'm just flying the aircraft and never think about protections. They don't exist for me. In any law. Protections are there if you personally fail.
That's why I'm wondering how you guys use your wonderful knowlege practically? You somehow prepare yourself, that you don't have this particular protection? And with protections you just relax and leave your fate to them?