A320 Flying the BUSS and avionics smoke in the simulator

[Jimmy Hoffa Rocks]

Question. Have you flown the A320 BUSS in the simulator in your airline ?
I would like to have A320 BUSS training in the sim, you?
What is it like flying the BUSS at high altitude?

¨To use the BUSS, the crew must first disconnect the three ADRs (air data reference - anemometric stations). Once these have been disconnected, the crew can no longer use them during the flight.
With the BUSS system, speed is no longer calculated by the Pitot probes, but by the aircraft's incidence probes. The speed indication, which is less precise, is presented in the form of green, ambre and red stripes. In a high turbulence situation at high altitude, the speed indication given is very unstable and difficult to use¨

How does it work configuring the sim for it ?

Our training in Europe, we always have to repeat the same engine failure drill twice a year, yet other failures training much less frequent, true in your airline?

Are the authorities in Europe, still behind the curve and out of date when have to repeat time and again the same engine failure drills ?


More avionics smoke training should be done in the simulator, urgently (look at Egyptair ) do you agree ?
When was the last time you did A320 avionics smoke in the simulator compared to engine failure/ engine fire?

What are statistical chances of having a engine failure versus avionics smoke in a A320?

[hph304]

Did the BUSS, quite easy to fly actually. At high altitude we immediatly initiated descent using unreliable airspeed procedure which is basically thrust idle, pitch at around 0 degrees. Once at lower levels, BUSS becomes more stable and reliable. Not all simulators have BUSS installed just like the ac. We activated BUSS as described by Airbus.

EFATO/approach/go around are mandatory items on every check, so obviously you have to do them every time. In my airline the abnormals/emergencies are picked by looking at incidents/accidents on the A320. Unreliable airspeed was quite an important item, just like high altitude jet upset recovery.

[Jimmy Hoffa Rocks]

cheers mate thanks
Thats what I mean, mandatory items, EF, may want to be reconsidered from twice a year to once

Did you also do the MCDU back up Nav? as well, worth training

[Fursty Ferret]

Works fine in our sims, seemed a useful tool. It's far more useful if you check what the pitch targets you're looking on the approach will be from the QRH first, as you can set the pitch attitude and get an instant idea of your speed from the BUSS.

[vilas]

Jimmy Hoffa and Fursty
I think there is a confusion in your mind about the BUSS because you are all the time talking about use of BUSS at high altitude and high altitude turbulence. The BUSS is not meant to be used at high altitude at all. At high altitude you use the same technique of pitch and thrust and descend to 250 if speed indications still remain unreliable you switch off all ADRs and you get the BUSS. It is simple flown something like the TCAS. Fly the green for speed and GPS altitude is displayed.
Firsty, I think you are mixing up, in the QRH for BUSS aircrafts the reference to pitch targets for approach has been removed because you don't need them.

[Fursty Ferret]

Firsty, I think you are mixing up, in the QRH for BUSS aircrafts the reference to pitch targets for approach has been removed because you don't need them.

Thanks vilas. The pitch/power tables went and then came back in our QRH...

Thought it was obvious that BUSS isn't to be used above FL250.

[Cough]

Vilas...

Imagine the same flock of birds that takes the pitot heads off also takes the AoA vanes off the aircraft... Tables are good!

[Denti]

Firsty, I think you are mixing up, in the QRH for BUSS aircrafts the reference to pitch targets for approach has been removed because you don't need them.

Not in ours, not even in those delivered this month nor any older ones. The approach pitch target table is still there.

[vilas]

It is possible that airlines with mixed BUSS and NONBUSS fleet have it in their QRH for all aircraft, sensible idea! But Airbus 1.8 STD QRH doesn't have them. Although the situation of birds hitting the aircraft from all over destroying triple redundancy is rather far fetched because unreliable speed so far have happened because of icing or maintenance errors, I am not against having the tables in QRH.

[Goldenrivett]

Hi vilas,
What is your latest information of the flight control Law an A320 would be in with BUSS actived, clean config & Gear Up?

Our latest simulator put us in Direct Law. "USE MAN PITCH TRIM" (which makes sense if you are trying to fly a constant Angle of Attack.)

But FCOM says we should be in ALT LAW.

Airbus Safety First Magazine issue 5 Dec 2007 thought it would be Normal Law. Page 21.
http://www.ukfsc.co.uk/files/Safety%20Briefings%20_%20Presentations/Airbus%20Safety%20First%20Mag%20-%20Dec%202007.pdf

Once Flaps 1 was selected, the simulator went into ALT LAW.

[vilas]

Hi Golden
The aircraft should not be in direct law but go to Alt Law and when gear down Direct Law. Failure of ADRs does not cause direct law (FCOM DSC-27-20-20 P 2/8). Double ADR failure will cause Alt Law and if the third ADR fails it will only remove the reduced protections and go to Alternate Law with no protection. There is no question of being in Normal Law. The Safety First doesn't state Normal Law. Change in Flt Ctl. Law with Flaps is very strange. It appears a Simulator glitch.

[Goldenrivett]

The Safety First doesn't state Normal Law.
The picture on page 21 shows green " " on the PFD for Normal Law.
I wonder why they they produced an "artist's impression" rather than a photo from the simulator?

[vilas]

Oh Ya! and I kept reading the whole article. Also below: FCTM AO-034 P 8/10


In addition, when the BUSS is active:
‐ The AP/FD and A/THR are inoperative,
‐ The STALL warning remains operative,
‐ The flight control law is ALTN LAW. The high angle-of-attack protection and VMO/MMO warning are lost,
‐ Cabin pressure must be controlled manually.

[Cripple]

Hi

For some MSN, ADR 1+2+3 FAULT has a level 2 note in PRO-ABN-34 which states that in the Clean configuration that the FLT CTL will revert to DIRECT LAW.

We have 2 different sims with BUSS. One gives ALTN LAW until gear down; the other, as per the post above, gives DIRECT LAW when clean, upgrades to ALTN LAW when F1 selected then back to DIRECT LAW when gear down. Hence I would say GoldenRivett's sim is correct.

I'm not sure what the modification is that causes the difference. Affected MSN seem to be in the 4000 series whereas those either side seem to stay in ALTN Law.

[vilas]

Can you give the MSN? Is the SIM STD1.9 that is the latest. STD1.8 goes to Alternate law and all these MSNs below go to alternate law.


Applicable to: MSN 0138-0185, 0241-0255, 0301-0497, 1818
Applicable to: MSN 0199-0240, 0264, 0932
Applicable to: MSN 0557-0758, 0943
Applicable to: MSN 0976-1010

[Denti]

Just checked the FCOM of a MSN in the 4100 range and it has that note, it is applicable to a range of MSNs from the 1600s up to the middle of the 4400 range in our fleet.

[Cripple]

Hi Vilas

As per my original post, the direct law in Clean config only applies to some of the aircraft in our fleet I n the range 4200-4800 (these were a block delivered about 5 years ago).

We have BUSS enabled aircraft from MSN approx 2000-6000+ and other than those above, they all go into alternate law with BUSS (until gear down as you would expect).

I think I am right in remembering that the range of MSN which go into Direct Law used to be wider in our fleet (incl. some 5000 series MSN) but it appears to have been changed as part of a mod program- which Mod I don't know.

We also have a 1.8 sim that behaves as GoldenRivett describes (I.e. Direct Law when clean).

I guess the answer is to do whatever ECAM and PFD tell you to do if you end up in BUSS - rather than trying to remember which mod state you have.

[vilas]

Cripple
It is very strange because I operated SIMs std1.8 new as well as updated and they go to alternate law. You should ask airbus for clarification through flt ops. Especially change of law with flap is difficult to comprehend besides this uncertain behaviour of different models can create doubts about the reliability of the BUSS itself as it is unreliable airspeed itself causes enough confusion.

[Cripple]

Hi Vilas

I accept your point but my view would be that the sim itself is not intrinsically wrong. It behaves exactly as some of our aircraft will in this situation and this is described (albeit well hidden) in the FCOM.

We are lucky that we have another (older) sim which reflects the other potential outcome.

I understand your scepticism about this, especially law changes with config but that is what the FCOM says and it is what the sim does.

The techno geek in me would love to know the exact mod details that drive this behaviour but the trainer in me just tells me to deal with it on the day - with the understanding and acceptance that different msn may behave differently. This understanding should help moderate the inevitable confusion when faced with unreliable airspeed.

Just my view anyway.

[vilas]

Cripple
I am very sure about what you are saying must be happening but I have seen a few issues with SIMs which are errors and they don't get sorted out and continue forever. That is why I suggested about checking from Airbus. The other thing, I am unable to locate anything in FCOM about when the BUSS is turned on whether it goes to alternate law or direct law. Can you please give some reference, the page numbers/chapters? Thanks

[Cripple]

FCOM PRO-ABN-34-NAV ADR 1+2+3 FAULT

Under associated procedures. Nb. The Level 2 note only appears for the range of MSN described above.

L1 F/CTL ALTN LAW
(PROT LOST)
Note:
L2 When the aircraft is in clean configuration, the flight control law reverts to direct law.

[ZFT]

Something to be wary of. Simulators (datapacks) have their own unique MSNs which may not correspond to any actual aircraft. Airbus no longer supply datapacks to tail numbers.

Specific FCOMs are supplied with these datapacks too.

[Goldenrivett]

Thanks Cripple,

I've found the same note for some of our MSNs now.
Very interesting and not widely understood.

[vilas]

Cripple
Got it. It is only for SIM std 1.8. I had seen it before but as Golden said didn't realise it's true meaning because in SIM session generally we do UAR after take off where flaps are always at Conf1 or 2. Also it immediately does not become clear that should you encounter UAR after retracting flaps or in clean configuration at altitude and switch off all ADRs it will transit to Direct law. I think Airbus should have explained it more in FCTM, especially because from FCOM as I quoted before, triple ADR doesn't transit to Direct Law but Alternate without protections. Another thing is std1.8 on ADRs do not process AoA input but IRs do that is why it asks you to put off all three ADRs while older ones without BUSS you got to keep one for stall warning. May be that has some connection and original and retrofitted systems may be behaving differently. Thanks anyway for the input it makes it so much clearer now.

[Cripple]

No problem. It took me a while to find the answer. As you say, the FCTM could at least mention it!

[Lantirn]

FYI

We were told when the BUSS was initially implemented that direct law is active until flap extension, then Alternate until gear down.

The simulator was in alternate law but the instructors had the info at this time that it was a glitch according to FCOM.

After some research I realized that this was only applicable only to one of our MSN's, which in coincidence happened to be the MSN representing the simulator.

The latest FCOM has completely removed this and all msn's now are at alternate law until gear down of course.

The sim was correct...

[ZFT]

As a matter of interest, airbus simulators no longer follow aircraft MSNs. They all follow a specific simulator MSN dependant upon standard and engine fit.

[Lantirn]

Yes, I meant the msn closer to the sim

[hikoushi]

Question for you gurus. For the newer aircraft that have the "BKUP SPD/ALT" buttons. We recently received an aircraft with these buttons installed; it is in the FCOM but not represented in our simulators.

How does this work exactly? According to the FCOM the captain or first officer can independently activate the BUSS on their respective PFD at any time by pressing this button, and it is reversible.

I assume that if you just reach down on a normal day and hit that button, the PFD simply displays the BUSS information in lieu of the normal (stilll functioning) airspeed and altitude tape, without affecting the flight control laws or ADRs in any way. Yes? No? What about the autoflight system? If for example AP1 is engaged and the captain decides to "see what that button does" does it kick the autoflight off, or does everything continue to function? FCOM PRO-ABN-NAV section references a couple of ECAMs the simply say "AP 1 (2).... DO NOT USE" which sort of sounds like they dont go away on their own.

Anyone actually used this thing yet?