SRS mode during windshear - A320

[vilas]

Chrono is started so that you don'exceed time limit for TOGA, not thrust limit and ECAM has no warning for that. EGPWS warning after takeoff comes not with low rate of climb but decsent.

[Flappo]

TOGA if required . AFAIK the bus is FLX single engine certified, in any case you just need to move the thrust levers from FLX to TOGA and move back to MCT, right?

[Natstrackalpha]

If a/p is on pull heading! You wouldn't want to be turning before out of shear! That's crazy!

Thats right!--------------(unless there is a rock in the way)

[vilas]

Hi guys
There was never any doubt about using TOGA and following SRS if available. But the scenario was we were in TOGA from take off. So when you reach 400ft i.e.( THR RED/ACC ALT) LVRCLB will flash also SRS changes to CLB. We ignore LVRCLB and keep the thrust levers in TOGA. We are in TOGA but FDs are not in SRS. in that context I had suggested if you are following the FDs, pulling speed to prevent pitch down to accelerate. It was not my intention to contradict SOPs. Now we have two options either move thrust levers out of TOGA(do not have to go to MCT) and quickly back to TOGA this gets the SRS but in GA mode or ignore FDs and fly 17.5 pitch with full back stick if needed. When FDs are there ignoring them is a tough job. If you had moved thrust levers to CLB then you reselect TOGA. You get back SRS in GA,you can follow SRS till default GA acceleration altitude. Also Airbus reccommends not reduce THR RED/ACC ALT if windshear is expected. I have confirmed that even in windshear, at THR RED ALT, LVRCLB wil flash and at ACC ALT SRS will change to CLB.

[sonicbum]

Originally Posted by vilas

You get back SRS in GA,you can follow SRS till default GA acceleration altitude. Also Airbus reccommends not reduce THR RED/ACC ALT if windshear is expected. I have confirmed that even in windshear, at THR RED ALT, LVRCLB wil flash and at ACC ALT SRS will change to CLB.

Hi vilas,

if you go back to TOGA and trigger the GA phase, the acceleration altitude will be the one set in the GO AROUND PERF page of the FMGC which will be, let's say, 1000 ft AAL of the destination aerodrome, correct ? So let's say if the destination has an elevation of 7000 ft, the SRS will stay there till 8000 ft.
Another question regarding the THR RED and ACC in case of wind shear. Airbus recommends not to reduce THR RED/ACC ALT if wind shear is expected but what about the recommendation to avoid NADP in case significant turbulence or wind shear is expected ? I have a little confusion here. Is there any docs from Airbus supporting the fact that CLB or OP CLB phase will engage at ACC ALT even if Wind shear is triggered ? I tried it in the SIM too and it is like you say but just want to make sure it's not a SIM glitch.

Thanks !

[Goldenrivett]

Hi sonicbum,

Is there any docs from Airbus supporting the fact that CLB or OP CLB phase will engage at ACC ALT even if Wind shear is triggered ?

FCOM DSC 22-40
"The windshear detection function is provided by the Flight Augmentation Computer (FAC) in takeoff and approach phase in the following conditions:
- At takeoff, 3 s after liftoff, up to 1,300 ft RA

- At landing, from 1,300 ft RA to 50 ft RA

- With at least CONF 1 selected.
The warning consists of:
- A visual “WINDSHEAR” red message displayed on both PFDs for a minimum of 15 s.
- An aural synthetic voice announcing “WINDSHEAR” three times."

Above 1,300 ft, windshear will not be detected nor displayed, so SRS will change to CLB even if you are still in windshear conditions provided the AA is <=1300.

the acceleration altitude will be the one set in the GO AROUND PERF page of the FMGC which will be, let's say, 1000 ft AAL of the destination aerodrome, correct ?

No.
Destination AA is only used after you have reached cruise ALT or activated the APP phase.

[timmyEGCC]

Destination AA is only used after you have reached cruise ALT or activated the APP phase.

Cruise ALT? Can anyone confirm that FMGC can NOT go into GA phase from phases other than APPROACH PHASE? (A320 FCOM DSC-22_20-30-20)?


My understanding also is that SRS GA mode can still trigger regardless of the FMGC phase provided Conf 1 or more selected.

[Goldenrivett]

Hi timmyEGCC,

My understanding also is that SRS GA mode can still trigger regardless of the FMGC phase provided Conf 1 or more selected.

Correct, but what AA is used to engage CLB and prompt you to select Climb Power?

[vilas]

sonicbum
Actually there is no document that ever said that in wind shear SRS doesn't change or CLB or OPCLB will not engage. But I confirmed it out of curiosity. TOGA after SRS has changed will engage GA mode and SRS will change at default ACC ALT not necessarily of destination. Wind shear detection is a low level function so NADP ACC ALT being 3000ft. it won't apply there.

[sonicbum]

Thank You all gents