>TCAS OFF - message inhibit

[Hardy Heinlin]

My old notes certainly show TCAS OFF appearing on the ground.

Hi all,

I need to revisit this thread because of a re-inquiry ...

The above quote is modelled in PSX, and since PSX version 10.0.6 it's inhibited between 80 KIAS and 400 RA.

BA seems to inhibit it all the time when on the ground. What are the exact criteria? Just "ground"?

And is it BA specific or a standard feature meanwhile? My option pages are full now! :-)


|-|ardy

[John H Watson]

Not to be confused with the "TCAS OFF" ND message which can be seen in photographs on the ground.

Unfortunately, I have limited access to Maintenance Manuals since my retirement. However, I was able to find manuals for British (BA) and Singapore (SQ) which describe a test procedure which, among other things, generates the >TCAS OFF message in (simulated) air mode (but that is not to say that it can't be generated in other ways).

Summarising/paraphrasing this procedure:

Align IRUs in NAV mode
Select ND Map Mode
Set mode switch to STBY....
Select TFC on ND....
Set ATC panel mode switch to ALTN RPTG ON. Make sure ND shows TCAS OFF.
Set mode switch to TA position. Make sure ND shows TA ONLY and TFC indication (Traffic may appear)
Set mode switch to TA. Make sure TA ONLY indication continues to be displayed.
Set mode switch to TA/RA. Make sure TA ONLY indication continues to be displayed.
Return mode switch to STBY.
Put flaps to 5 or less (to prevent aural warnings)
Put the gear lever to OFF (after installing ground locks)
Simulate air mode by pulling specified air/ground CBs (after pulling other safety-related CBs)
Set ATC control panel to "1" or "L" (fail lamp should  not be illuminated)
Simulate a baro altitude of 40,000' (to minimise interaction with aircraft in area) on both ADCs.
Set mode switch to TA/RA
Simulate a radio altitude of 550'. Make sure ND shows TA ONLY
Slowly increase RA to 2400'. Make sure TA ONLY message clears when the RA is greater than 1100'.
Pull ATC-L CB. Make sure the ND and EICAS shows the TCAS OFF indication.
Pull ATC-R CB. Make sure the Upper EICAS shows TCAS SYSTEM Advisory.....

Further tests are specified (with TCAS test set placed near lower TCAS antenna).

(EDIT). Perhaps this table clarifies things (although it's for an aircraft with a different control panel with different settings).

http://www.iinet.net.au/~b744er@ozemail.com.au/PSX/TCASMessageTable.GIF

[emerydc8]

From the Atlas expanded line ops:

Preflight Setup:
. . . .

VOR/ADF switches.
 ND mode and Center switch: As desired.
 ND range selector: As desired.
 8F: It is recommended to select the ARPT switch on for the airport moving map on the ND. Recommended range 5 miles or less.
 Traffic switch: Verify TCAS OFF is displayed on the ND.
 Weather radar switch: Off. No weather radar indicated on the ND.
 For QFE operations, see SP 10.2. LCF: QFE operations are prohibited. FOM 11.2.6.

Taxi Out Procedure:
. . . .
Captain: Taxi light on.
o Captain or PF:
 Parking brake: Release. Begin taxi.
 Steering: Check.
o Crew: Verify the flight instruments and displays:
 PFD: V speeds. FMA: Blank, TOGA – TOGA, VNAV armed, and LNAV armed if desired. Altitude and heading displayed and correct.
 ND: Active waypoint and TCAS OFF are displayed.
 EICAS: Thrust, RTO, and flap setting.
 CDU: Check the V speeds on the PF's TAKEOFF REF page. Check PM on LEGS page 1.

Before Takeoff Proedure:
. . . .

 Transponder: Select TA/RA. 8F: The ALT OFF function is the furthest selection to the right and should not be selected.
 Verify:
 The transponder code.
 TFC –TCAS TA on both NDs.

[Hardy Heinlin]

Possibilities:

• Atlas text is wrong and BA sim is correct

• Atlas text is correct and BA sim is wrong

• It's company specific


But I'm too tired to add another option for this ... The option pages are full and I don't even know the exact criteria the BA sim uses ...

[emerydc8]

Here's a pic of the ex-ANA Flight Training Device on the ground. But I can understand how tired you must be with all the beta versions coming out. I don't mind either way.

https://drive.google.com/file/d/0B-WRh0Hf7VdZMGR0VTAxU0dteUU/view?usp=sharing

[ADDENDUM]:

Hi Hardy, I just wanted to confirm that we are both talking about the TCAS OFF on the ND and not the EICAS advisory message TCAS OFF. I think we are both on the same sheet but just wanted to make sure.

[John H Watson]

Possibilities:

• Atlas text is wrong and BA sim is correct

• Atlas text is correct and BA sim is wrong

• It's company specific


But I'm too tired to add another option for this ... The option pages are full and I don't even know the exact criteria the BA sim uses ...

What, precisely, is different? The topic title refers to the EICAS message (preceded by the caret). The careted version seems to be the one which has the "on ground" inhibit, and my table shows the exceptions (based on mode selection). I'd say the FCOMs are just generalising.

There are plenty of photos of the ND "TCAS OFF" (uncareted) on all the airlines on the ground on airliners.net (BA, QF, Atlas, et al)

[emerydc8]

What, precisely, is different?

I'm not really sure now. I apologize that I may have muddied the water because I was thinking about the TCAS OFF on the ND -- not the EICAS advisory message TCAS OFF. I did find something on this in the NCA 747-8F manual that shows the EICAS message is inhibited on the ground up to 400'.  https://drive.google.com/file/d/0B-WRh0Hf7VdZSmJUWkVOWUVtVW8/view?usp=sharing

I also verified this in a Polar 744 manual -- EICAS TCAS OFF is inhibited on ground up to 400'.

Not to be confused with the "TCAS OFF" ND message which can be seen in photographs on the ground.

I totally missed this. Sorry, John.

[Hardy Heinlin]

What, precisely, is different? The topic title refers to the EICAS message (preceded by the caret).

In PSX and on your table (thanks!) both TCAS OFF messages -- on the ND and on the EICAS -- appear and disappear under the same conditions, aside from the EFIS TFC button which can blank TCAS OFF on the ND (in PSX and on your table).

(I just need to make some minor adjustments for the ground tests, but that's a different subject.)

There are plenty of photos of the ND "TCAS OFF" (uncareted) on all the airlines on the ground on airliners.net (BA, QF, Atlas, et al)

According to your table, whenever TCAS OFF appears on the ND, the EICAS too shows >TCAS OFF.


How do BA pilots set up their ATC panel for taxi?


Regards,

|-|ardy

[Britjet]

I have just tried this in the BA sim.
TCAS selected to STBY or TXPDR on the ground - TCAS OFF on the ND. Nothing on the EICAS
TCAS selected to STBY or TXPDR in the air - TCAS OFF on the ND and >TCAS OFF advisory on the EICAS.
(No failures as such, just switch selections..)

So from what I have seen, there should be no TCAS OFF on the EICAS on the ground.
(BA selects TXPDR pre-start, and RA/TA prior to take-off.)

HTH

Peter

[Hardy Heinlin]

Thanks, Peter.

Now if somebody can prove that the real-life BA 744 behaves like the BA sim, I'm convinced that the BA sim is correct and that it may be BA specific (as it disagrees with that engineering table above).


Cheers,

|-|ardy

[Britjet]

Actually the sim I was in today isn't BA-specific as such - it has GE engines and is used wet by other airlines.
I am in a BA specific sim tomorrow so will look again, but there is no question of the BA sim being different to the aircraft - particularly with something like this - it would stick out like the proverbial "sore thumb" to pilots on their checks, so it wouldnt be acceptable for it to be different.

Peter

[emerydc8]

TCAS selected to STBY or TXPDR on the ground - TCAS OFF on the ND. Nothing on the EICAS
TCAS selected to STBY or TXPDR in the air - TCAS OFF on the ND and >TCAS OFF advisory on the EICAS.
(No failures as such, just switch selections..)

That would explain why I have never seen a TCAS OFF EICAS advisory. As long as you turn the transponder to RA/TA prior to takeoff and don't turn it to STBY or TXPDR in the air, you should never see it.

[Hardy Heinlin]

OK, I'll make that an option. But this will be in a later update because I'll have to redesign the layout of the Model pages as they are full now.


|-|ardy

[Hardy Heinlin]

I have an idea.

The option is active if the rego starts with "G-C..." or "G-B...".


|-|

[Britjet]

suits me!
Peter

[Hardy Heinlin]

Peter, do you set ALT RPTG to OFF for taxi?

[John H Watson]

According to your table, whenever TCAS OFF appears on the ND, the EICAS too shows >TCAS OFF.

I see that now. I misread the table. The messages can be independent, but it involves turning off the EFIS TFC button (which you wouldn't do).

I'm just wondering where failures fit into this picture. e.g. ATC Left CB pulled with ATC Left selected.

(EDIT)
I just found some Boeing Service Letters for EICAS software upgrades:

747-SL-31-060-A 28th October 1998
Applies to all Pratt and Whitney powered 747-400 airplanes prior to (production) line number xxxx

747-SL-31-061 29th October 1998
Applies to all RR-powered airplanes.... etc.

747-SL-31-03 16th November 1998
Applies to all GE-powered 747-400 airplanes.... etc.

The applicability of these service letters is not easy to understand. There are references to airplane (production) line numbers, aircraft with certain hardware, software, etc. However, I believe airplanes delivered after these line numbers already came with the software as standard.

IDS software Update:

>TCAS OFF (Level C) Revised logic to inhibit the message if radio altitude is less than 400 feet.

There were literally dozens of logic changes in this software update. Note that this was about the time, the IRU align countdown was added. EGPWS, Predictive Windshear and FPVs were also appearing

As you may recall, Hardy, not everyone updated their software (I remember years after the IRU align timer appeared on our fleet, there were still airlines which didn't have theIRU align timer). Some aircraft would have required hardware changes to allow the activation of some of the features mentioned in this software upgrade.

[John H Watson]

P.S. Some other notable changes in the software.

Revised EGT start limits for inflight starts (higher than on ground start EGT limits) (PW)
ENG X START EGT (Status) message added for inflight engine start EGT exceedances (PW)
Inhibiting of the (optional) TCAS 3nm range ring in the 5nm ND range.
>BRAKE SOURCE three second time delay
AIR/GROUND SYSTEM (Level C) message added

[John H Watson]

P.S. There is a high probability that the table in my Engineering notes wasn't updated after the software upgrade was carried out. Assuming this, does this put us all on the same page? 

[Hardy Heinlin]

In this case I will link the new option not with the BA model rego check ("G-B", "G-C"). I'll link it with the check whether the IRS align timer option is installed.

The timer isn't installed in PSX's Atlas Air model, for example. So this model will show the >TCAS OFF message on the ground.


|-|