View Full Version : A320 MCDU Approach preparation

24th Oct 2008, 18:00
During approach preparation,why don't we set Transtion level on the MCDU approach page instead of default transition altitude which is shown there?
It can act as a reminder when passing the transition level during the descent .


24th Oct 2008, 18:43
Forgive me if I'm wrong, but I believe some A320s (the newer ones??) actually do display TRANS LVL on the Appr page, and some don't. I think on the older ones it's just TA.

May be wrong though!


25th Oct 2008, 04:47
Even if it be so, why is selection of Transition Level on the MCDU approach page discouraged?Any technical reason?

25th Oct 2008, 06:24
Hi there,

I think you will find that the Transition Altitude on descent in the MCDU, defaults to what it is on climb. On the 320's I fly the Trans Level is then correctly loaded, when the STAR is selected. If operating to a port without STAR's, I am in the practice of entering the appropriate Trans Level.

What do you mean "discouraged"? It's not something I have ever come across?

Hope that helps a little...

25th Oct 2008, 07:21
TRANSITION LEVEL doesnot exist on the Airbus families, there is only TRANSITION ALTITUDE, you have to use it as transition level during descent although it is referenced to transition altitude.
The Airbus test pilots, made it worst on the THALES FMS2, they asked that the defaulted transition altitude on the approach page should display defaulted transition alitude (in the AMI) + 500 feet to cope with low QNH:ugh:
So guess what :confused: we have to correct it EVERYTIME:eek:

25th Oct 2008, 09:46
He says it's discouraged because the manual, I believe, says:

The crew should not modify this default TRANS FL value, if it slightly differs from the Transition Level specified on the approach chart or reported by ATC.

Why that is, I have no idea. Surely changing the value wouldn't harm anything?


25th Oct 2008, 09:49
there is only TRANSITION ALTITUDE, you have to use it as transition level during descent although it is referenced to transition altitude. Incorrect. You may want to use it as a TL reminder (STD flashing on PFDs) modified to the value applicable for given runway / pressure. Or, you may want to keep/correct it as appropriate to relevant TA, so that you get the flashing reminder during GA when climbing, so not to bust your GA FL. It is a tool and well educated operateur :} will use it as (s)he sees most benefical.

Of course, generally, one is better off following employer's standards (a.k.a. SOPs). Of course, there are ten in a dozen aircraft not equipped with such feature and all flying gets performed safely. It is better that automation guidlines do not become obstructing to procedure planning and situational awareness.

FD (the un-real)

Its the Pleats
27th Oct 2008, 00:43
The A320s I fly automatically inserts the correct Transition level/altitude depending on where you are going. Ie over to NZ, FL150 pops up in the PERF page etc. Maybe we have newer software packages?

27th Oct 2008, 01:38
He says it's discouraged because the manual, I believe, says .... Now where exactly is that from? Not manufacturer's FCOM 3 neither 4 or FCTM.

27th Oct 2008, 02:56
In one particular airline, their BARO REF is set to STD when cleared to a Flight Level and QNH when cleared to an altitude, provided altitude restrictions for SIDS/STARS are complied with and MSA is attained on a climbed. Having the Transition altitude set in the approach page is for reminder only. When there's a request from ATC for altitude/level passing, QNE or QNH is momentarily set for the reply only.

Metro man
27th Oct 2008, 09:02
In China, transition levels differ depending on QNH. You need to modify the T/L for unusually low or high pressure settings. Also, sometimes the level in the box differs from the approach plate, if the box is in error it can be corrected.

Some of our aircraft use T/A and some T/L, depends who makes the box.

29th Aug 2010, 20:20
fcom 4 does not recommend changing the default TL value, and i have noticed how the value changes as you go into the lower end of QNH, still would like to understand the logic behind.

29th Aug 2010, 22:04
fcom 4 does not recommend changing the default TL value

Really? This is just a reminder, so if you want to be reminded when crossing TL just modify it accordingly.

See below:

http://nsa20.casimages.com/img/2010/08/29/100829100027685298.jpg (http://www.casimages.com)

TRANSITION LEVEL doesnot exist on the Airbus families

Incorrect. Our latest MSN (FM2+ equipped) display TRANS LVL in the PERF APPR page.

30th Aug 2010, 07:04
i dont know how to upload the page, but have a look at
FCOM 4.05.50 Page 12.
tell me what you think

30th Aug 2010, 10:41
I had a look, it's completely coherent with the page description section.
It says again that you can modify it:

http://nsa19.casimages.com/img/2010/08/30/100830114113362228.jpg (http://www.casimages.com)