Airbus aircraft sidestick target on PFD
 

How do the pilots use the target cross on the PFD ?
Appears after engine start and disappears after take off.
Im not a pilot and i was wondering how it was used.
Thanks

Thanks for all the replys.

What are we agreeing to as the correct use of the indication?

I use it to position the ailerons into wind at rotation on a cross wind takeoff.

Really.....?

The white Maltese cross and box on the PFD (Primary Flight Display) are used during the flight control check.

The box represents maximum sidestick deflection. During the control check, one pilot will move their sidestick to the limit in all directions in sequence. The other pilot watches this and checks that the correct flight controls, (ailerons, spoilers, elevators and rudder), move the correct amount in the correct direction on the flight control page, which is automatically called when the flying controls are deflected during taxy out.

On take off, the cross and target remain until about 50 or 100' above the ground, (can't remember which), so the Pilot Monitoring can see the control inputs being put in by the Pilot Flying.

{Further to the AF447 crash, I made the suggestion on that thread that during flight this visual be replaced on the PFD's in flashing red if a sidestick was ever held at a limit for more than say 5 seconds, so the other pilot could see what the pilot flying was doing with the sidestick.}

hetfield,

During takeoffs with very strong crosswinds some aileron may be required to keep the wings level. You don't want to go so far as to deploy the spoilers so the cross can be used to ensure side stick deflection is no more than a third. It's all in the FCTM.

Don't have any FCOM A320 since 1998.

If AB became wiser and has changed this subject, I apologize my comment.

You apparently don't monitor yourself a lot then ... At 50 the cross has gone for a while already.

speaking of which: anyone happens to have a reference about what exactly triggers the double crosshair ("sidestick order") to disappear from the PFD after airborne?

I tend to feel that on newer (MSN 4000++) aircraft is disappears somewhat earlier than on the older ones (MSN 1000-) but I could not find an exact reference in the FCOM.

Cheers

It is in my FTCM to avoid deploying spoilers on one side. But it is not specified to use the cross for that matter ... Would you have the precise quote to state so from yours ?

I heard A rumour that Airbus are looking into ways of making the Airbus more Crosswind friendly. Ie more leigh way with sidestick vs spoiler deflection, Is there any truth in this?

Well call me old fashioned, but I am usually more concerned with; positive climb - gear up - monitoring PF's flying - noise abatement turns etc. to notice exactly when it goes.

I will check for you next time I fly.




U

FCTM
The reference to the cross position is from our company issued training study guide. It states that the limit of sidestick to avoid spoiler deployment is when the edge of the cross is on the central index.

Hello chaps/chapesses,

In case it's of interest, and at risk of irritating those who have seen it before, I wrote this as part of a post in 1988. It came out of a general discussion on A320 crosswind handling, and was much assisted, IIRC, by Confiture and Lemurian (interesting combination!). Unofficial,of course, and no FCOM or FCTM references, I'm sorry to say:

"CROSSWIND TAKE-OFF
A small amount of into-wind aileron can be selected before starting the T/O run, avoiding "cracking" the spoilers.* During rotation, the upwind wing tends to rise in the conventional manner, and can be countered by retaining into-wind aileron. As the main L/G lifts off, any downwind rudder will be eased off, yawing the aeroplane into wind. This will temporarily assist the aileron. Half a second after lift-off, however, Normal Law in roll is introduced (AND the white cross on the PFDs has disappeared). At that point, any remaining roll input needs to be released.
"5 seconds after main L/G lift-off, Normal Law also becomes fully effective in pitch. Stick-to-elevator control is now removed, and pitch-attitude can be refined by small nudges of sidestick.

" * Roll-spoiler deployment can be avoided by placing the PFD white-cross so that its inner edge is not noticeably to the side of the centre spot."

Now, 5 years later, I realise that I neglected to mention the need for some forward stick on all take-offs, particularly I suppose on a wet crosswind one. This makes it a bit more difficult to judge how much roll (aileron) command you are selecting, and to avoid "cracking" the spoilers. If in doubt, however, you will notice that the F/CTL page appears briefly when you first displace the stick, and enables you (if you are ready for it) to confirm that the spoilers are still stowed. If you miss it, briefly select the page manually.

Regards,
Chris

I agree 100% with Smash Bugger

It's not used for Flight Control checks, the PM looks at the Flight Control page to monitor the controls. The Maltese cross is only for the PM to monitor what the PF is doing on the ground.

As has been discussed ad infinitum on other threads, you cannot always see what input is being made to the opposite sidestick.

If a sidestick had been replaced and wired up backwards (it has happened), then the sidestick might be moved say full left but the controls might go full right. Or a flight computer might have a fault which reverses the sidestick inputs. By crosschecking the maltese cross with the flight control page, I am double checking that the sidestick direction and the flight controls are moving in the same sense.

My original answer to the OP was: which seems pretty clear to me?


U

Erm, it's just a point, but the side-stick position indicator on the PFD is just that, it's not a target for anything.

And, it's not a Maltese cross anyway; that consists of 4 isosoles triangles joined at the centre; if anything it's a German cross.

so there.

Thank you SSB for that wonderfully enlightening post. I'm sure we are all much clearer now. Thanks.

I sincerely hope that neither you nor anyone else ever gets a control reversal caused by a faulty sidestick, ELAC, SEC, or PRIM, but with my past knowledge and experience as an electronics engineer, I will continue my double cross-checking. :)


U

From my research smashbugger explanation is what I found .

So you're suggesting that while I Taxy the Aircraft I look down watching the cross on my PFD while the PM also goes heads down watching the Flight Control page to check each surface moves the correct way????????

That sounds like a good way to come to grief. :{


From the A330 FCTM:---


“Flight Control Check”

PM -Monitor F/CTL page.
PF -Apply full back sidestick followed by full forward sidestick, then release.

PM - "Full up, full down, neutral"

PF -Apply full left sidestick followed by full right sidestick, then release.

PM- "Full left, full right, neutral"

PM -Monitor F/CTL page. Follow through on the rudder pedals to confirm full and correct movement.

PF -Press the PEDAL DISC pb on the steering handwheel, smoothly apply full left and full right rudder and then return the rudder to neutral.

PM -"Full left, full right, neutral"

Ensure that the PM calls are in accordance with flight control inputs

PM Move you own Sidestick as above calling out movements etc.


It's not Rocket Science people.:ok:

Strewth, why is this so difficult?

No; the pilot taxying is taxying - eyes out of the cockpit.

Pilot monitoring has eyes inside the cockpit for the control check. PT says 'control check' I look at the GERMAN cross to see what the opposite sidestick is demanding, then I look at the flight control page to see and confirm that the correct flight controls have moved in the correct direction and by the correct amount.

Yes, if PT moved full left and PM saw and called full right, they would both know there was a problem. But what if PT was tired after a long day, and on the 6th sector there were distractions during taxying and did not register that when s/he pulled full left, PM called full right?


U

What if the guys misread the cross too..........:E

Besides you can see the other crew member stirring his stick out the corner of your eye.........:eek:

Guys....

As so often happens, several of you have gone off at a tangent; getting into a heated argument about a side issue. In the meantime, I've contributed a thoughtful post (see previous page) which directly answers the question originally posed by granard.

granard has since edited his post, and asks:

"Thanks for all the replies.
What are we agreeing to as the correct use of the indication?"

Any comments?

PS
Provided the PF does not rush the flight-control check, it's a cynch for the PNF to monitor both white crosses reaching full deflection, as well as the appropriate control responses on the F/CTL page. The PF simply holds the stick at full deflection until the PNF is satisfied, which he indicates by whatever verbal response is defined in your airline's SOPs. The PF then releases the stick. When it reaches neutral, the PF waits for the PNF to confirm that the flight controls (and both white crosses) have returned to neutral.

What makes you think that the system which displays the GERMAN cross will show a different indication to the control deflection? If there is an error, it will affect both presentations in the same sense.

Should be used, while PM, to confirm side stick neutral at the "100 knots" callout during the take-off roll. Also useful to check if the PF applies back stick at Vr.

Cheers.

OK. Let us suppose the output of the sidestick is sent on a data bus or wires both to the DMC's, which generate the white crosses, AND the flight control computers, which of course move the controls. However, let us suppose that either the DMC or a flight control computer has a fault internal to itself, (for example a dry joint)*, which reverses the sense of the sidestick - hey presto, one system thinks 'stick left' the other thinks 'stick right'. The box appears after engine start (i.e. before taxying), and not on application of take-off power - why would that be if it was not to provide sidestick position info during taxying?

That's my logic for my extra check, (which by the way takes all of half a second to perform). From what I know about electronic circuits and dry joints etc., this is what I will continue to do.


The OP wanted to know what the white cross was used for. I think that myself and others have answered their question.


U


*For those who may not know; a dry joint is a faulty electrical soldered connection in a circuit, which results in an intermittent electrical connection. Sometimes the joint is electrically sound, other times it is open circuit. These joints can and often do look perfect to the naked eye, and when electrically tested can appear sound. However, when the circuit heats up to operating temperature the joint can go intermittent. Dry joint faults are very difficult to trace.

Sidestick position cross
 

quote:
The Maltese cross is only for the PM to monitor what the PF is doing on the ground

unquote.

Not really!!!

U is right on, obviously flying 330.

The sidestick cross indicates the position of the sidestick.
Is used by the Pilot Flying during takeoff.
For example: Half scale Deflection downwards, until 100kts during the takeoff roll when it is placed on the horizon line on the PFD.
Then aids stick position indication when rotating to the appropriate angle at VR.
As mentioned, during crosswind takeoffs the sidestick is deflected to half a cross deflection (into wind) until, as described above, the aircraft rotates and weathercocks into wind, as in a conventional x-wind takeoff. . .
after which the cross disappears.
Some, operators prescribe full cross down in a crosswind takeoff with the into wind input, I don`t like this method, but is the way to do it whether I like it or not.

:added later . . .My point, though perhaps poorly laid out, is, that, the white cross is an indicator of sidestick position as opposed to anythingelse, like, flying controls.

And, the original question is/was: "How do the pilots use the target cross on the PFD ?" And, the answer is what I have written above.

ton pi

You would be welcome to quote your FCTM if and how it states so ?

You have obviously also missed a notorious serious incident report.
Cross is certainly not to be used by the PF for rotation.


You are definitely correct Chris, the initial Q. What are we agreeing to as the correct use of the indication? needs further consideration ...

SSI
 

For info the SSI / maltese / german/ swiss cross etc... Used to disappear after ground to air switch over... Then Emirates had a near hull loss as the crew used (wrong) training info during a takeoff out of
Jo berg some years ago... You can read about that somewhere else i guess.. After that incident AB modified it to disappear at NW extension ... You can verify this in the sim if youload the aircraft really aft in Cog and may note on a rough runway setting that it drops in and out as the aircraft goes light on the NW ...

i think all aircraft should be modded like this now but could be wrong..

Most of the remaining posts are pretty spot on regards limited use/ value to most parts of the operation.

WJA

Nobody seems really to agree on the way to call it after all but is it that surprising when Airbus itself names it Sidestick Order Indicator in the FCOM but Stick Cross Symbol in the FCTM.
On the same order, its function is also ambiguous and has evolved following serious incidents. Was it avail at all airborne in the early days, maybe for a few seconds after take off ... Chris ?
Now its time for being displayed has been reduced to a minimum and the advise not to use it by the PF during take off is clear.
The single note I can see to promote its use is addressed to the PM to validate the PF initial stick input. Interconnected sidesticks would do that nicely and much more.

Salut Confit,

Regret I cannot remember exactly when the "white cross" (as I usually call it) disappeared after take-off. And I don't know if the logic ever changed. I don't remember ever watching the white cross after 100kts, even as PNF.

As you know, the only Airbus FBW I flew was the A320 family, but I'm very interested in woodja51's post. Until now, I have assumed that disappearance of the white cross may be part of the logic of the introduction of Roll Normal, and the gradual introduction of Pitch Normal. My old FCOM says these two processes start when the a/c becomes airborne, which implies the main L/G weight switches. But we know that the nose L/G also has weight switches, and woodja51 says the disappearance of the cross is now on that. I presume this may not apply to the A320 family?

So, woodja51, what about the control laws switching? Presumably, that still uses the main weight switches?

Returning to the original question, I think the white cross is useful for the PF at the very start of the take-off run (partly down, and not too much left or right). At 100 kts, when the PF has finished releasing the down-input, he/she may want to glance briefly to check that the desired aileron (if any) has been maintained. After that, forget it.

Control law change
 

Chris ,

Not able to answer your flight control changover regarding WOW switches.

Have I missed something but does the FCOM not say half stick forward on take off to ease to zero at 100 kts except when xwind > 20 kts or any downwind then to use full forward stick ?

This is a 330 of course so could be diff on other types....

Hlaf stick is where the stick spring pressure increases or half a cross down by my reckoning. The same spring pressure increase in aft stick provides a good tactile input to correct rotation input to commence with from what I was told and do ... Before the cross disappears it will get to about 10degress NU before the jet starts to react and NW comes off... Assuming a 2.3-3 deg pitch rate or so...

Is that of any assistance ? Oh and the small left / right input should be eased out too and allow roll normal to control the drift effect as the rotate proceeds from what I was lead to believe.... Seems to work to me in 6000 hours in the LHS on it.

Pitch and lateral control switching (ground - flight) is not related to weight on wheels. The trigger is when the pitch attitude is greater than 8 degrees. At this attitude, the timing starts for a gradual transition from ground to flight mode. That's how I read my (A320) FCOM anyway!

I don't think the side stick indicator logic on the fleet I fly has been updated on all variants and cannot find the memo we were sent a while back about this. The newer aircraft have a new DMC standard (green VDEV scale on PFD in DES) and I think the new logic could co-incide with this standard.

Thanks Natstrackalpha. :ok:

Having recently flown, (A330), I agree that the white sidestick position indicator does now disappear soon after rotation.

So: Yep; Confit; you're right.

However, I'm sure that some old A320's I used to fly kept the indication to 50 or 100', because I remember using it to watch what PF did with the controls during take-off and rotation when I was learning to fly the thing.

Another reason for the white sidestick position indicator being displayed on the take-off roll is of course to monitor a sidestick fault. If a sudden control hard over was seen, PM could shout stop! (below V1).

U

Hi woodja51,

I can't be of much more use in this discussion, because the last time I was in an Airbus FBW cockpit was the end of 2001! Prior to that, I was a line capt and line checker for 14 years, but only on the A320/A319. So even my A320 FCOM and Training manual are way out of date. I think we used to use half down-elevator, judged by placing the white cross half way down, until 80 kts (as per my post #14, above). Can't remember if we ever modified our policy to use extra for strong crosswind or downwind, but obviously see the argument; particularly on a wet runway, where nosewheel adhesion is important while the rudder-fine steering is available. Even at zero IAS, the down elevator is of some effect for take-off on the A320, due to the slipstream effect.

Quote:
"Half stick is where the stick spring pressure increases or half a cross down by my reckoning."
Which is it? Half stick or half a cross? Half stick puts the whole cross well below the black box, IIRC.

Quote (my highlighting):
"Oh and the small left / right input should be eased out too and allow roll normal to control the drift effect as the rotate proceeds from what I was lead to believe.... Seems to work to me in 6000 hours in the LHS on it."
Yes. One of the commonest handling mistakes I saw - often from the P3 seat on line-checks - was the upwind wing rising during rotation. The theory in the early days on the A320 was that Roll Normal would prevent that happening, but it quickly became apparent to me that this was not the case. The wing would rise immediately rotation was started, before main L/G lift-off (as you would expect). However, many of our trainers clung on to their assumption in the face of all the evidence... :{

Very simple for me.

Until airborne I can ensure as Captain that the f/o is not putting too much lateral control - see Air2000 Bristol tail strike, and then I can monitor amount of backstick in rotation.

What is your opinion then on the Ziegler's concept on which Airbus is built that the other pilot don't need to know how the PF is soliciting the flight control commands ?

Hi CONF iture

I think over the years it can be seen that there have been certain flaws with the concept of the Airbus design. My job is to use best resources to safeguard the aircraft. That includes on day 1 of line training a 200 hour cadet, keeping an eye on his/her initial control inputs. Would not be the first time I have had to takeover during rotate as the f/o has full back stick. If I waited till airborne (ie not monitor the cross) it would be too late.

So with all the comments that have being made, what is the final use of the white cross?

Is it to allow the PF to observe during takeoff the amount and direction of the side stick and at the same time to allow the PNF to observe the PF inputs.

But Roll Normal is not fully active before 2 sec after attitude is over 8 deg. Until that time the roll is still under Ground Mode when aileron deflection is proportional to Sidestick deflection. As you state, pilot's action is necessary to prevent the upwind wing to rise during rotation.

The rule seems to be now that the white cross disappears when the Nose Landing Gear is fully extended. Are your aircrafts still displaying the white cross up to the Main Landing Gear extension ?

Good question....not sure as once wheels off ground I am more interested in the change of flightpath. My gut feeling is that it disappears during the transition to flight mode.