A320 IAE Autoflight

[captanskywalker 1]

Hey, I have seen this issue posted many times in the forums but never a fix or not 100% my issue but very close, this is after I takeoff and reach cruise level  and level off and I have the autopilot on and all knobs pushed in for managed mode the 320 keeps over speeding and climbs to reduce speed and then once the speed is low it descends for cruise level but this causes over speed and the same thing will just keep repeating, after much fighting to bring the speed down with spoilers and flaps I will reach cruise level again but to keep the speed and level stable I have to pull out the speed knob to use self managed speed and even this sometimes does not work, even going off autopilot it's still a fight, now here is the thing this ONLY happens in the IAE engine type, the CFM type works perfect! Now I want to solve this for the main reason I fly Jetstar a lot but i can not find a Jetstar livery for the CFM model, so if I can please have some assistance with this issue that would be grate, but and I must stress this please don't reply with what autopilot mode am I useing as I clearly state this above and don't ask me to read the manuals and learn to fly as I know how to fly this aircraft and as I can fly the CFM model with no issues at all this is not the case. So thanks in advance for reading this and any help you can give. Luke.

 

[The Dude 6537]

Let's first be clear here. It seems you do not have an autopilot issue but an autothrust issue. Could you make a screenshot of the PFD when these problems first occur? What CI do you fly? Was there a large windchange when the problem starts?

 

Thanks

[captanskywalker 1]

I will get a screen shot posted asap and yes auto thrust is what I meant, lets also be clear this only happens with the IAE 320 every single flight regardless of weather or any other factor, I fly it just the same as I do the CFM 320 which works fine I do not believe it's how I'm flying it or the settings in the flight deck.

[Goshob 23]

Hi,

I had similar situation with a320 after a missed approach. The procedure was full thrust and climbing to 3000 ft and after that turn for another attempt. Unfortunately the plane become "crazy" during the climb. Thrust increased, climb also and all control buttons become inactive. The plane went to more than 40,000 ft without any possibility to control it. Even thrust levers to 0 did not work. The only way was to turn off the FSX. Unfortunately I was unable to take any screenshots while trying to apply any possible actions to make it back in command.

Would appreciate any comments.

[The Dude 6537]

Hi Goshob,

 

how many times did this happen to you? 

[Goshob 23]

39 minutes ago, The Dude said:

Hi Goshob,

 

how many times did this happen to you? 

It is already 6 times, including 2 today. My platform is Aerosoft a320 / 321 FSX:SE

 

[The Dude 6537]

Could you post the details about your flight so that we can fly and try it for ourselves? And just to be sure, you do have the latest version installed as admin and have FPS above 18?

[Goshob 23]

Hi,

Here are the details requested earlier:

- Route: LFPG OPAL1A OPALE UT421 KESAX UT426 DIMAL UT10 ALESO BIG4B EGLL (Including SID and STAR);

- Departure RWY: 27L

- Arrival RWY: ILS27R

- Flight: F240;

Aircraft: Airbus A320-200;

SIM version: AS_AIRBUS-A320-A321_FSX-P3DV2-P3DV3-FSXSTEAM_V131 

Platform: FSX:SE

I had to do 2 times Go around yesterday due to height mistakes and not properly following the glide slope. Both times go around decision was taken when being on D0.5 and the plane was higher than required. I had adjusted the AP as per the requirements of the RWY, i.e. course 318 deg and climbing to height 3,000 ft (not pressing the altitude button). The course was followed somehow, but the thrust in both attempts become excessive and plane went very high, as mentioned in my previous post. Finally it remained uncontrollable and the only option was Esc (close the SIM).

Similar situations I had in LOWW and EDDL, but it was couple of weeks ago and I do not remember the details.

Hope someone may help.

[DaveCT2003 2553]

Would you please tell us which version of the Airbus you have installed?  1.30x, 1.31?  You can find this by going to your main flight sim folder, then Aerosoft/Airbus and open the Product.CFG file in Notepad.

 

Thanks.

 

[FraPre 89]

He wrote V131.

[DaveCT2003 2553]

Thanks. I ask because we had similar/same issues with a previous version of the aircraft.

 

 

 

 

[Goshob 23]

Hi,

I confirm the version is 1.31.

[Goshob 23]

Hi,

I would like to share an observation, which may help in investigation the subject mentioned above. The reason was the 2 missed approaches, which were mentioned in my first post.

I noticed that the plane (AP) does not follow properly the descend heights and the result is remaining too high when approaching the RWY. A friend (who has more free time) and I decided to fly the same route mentioned above several times with the same plane, at same day, same time, same F240 and same weather conditions just for reference. The control was left fully to the AP because it is an ILS approach anyhow. It was observed that 2 of every 3 attempts the plane reaches WP P (D 7.5 IRR) where the glide slope starts, at a height more than 3,500 ft instead of 2,500. The left and right arcs before that are very rarely flown at 6,000 and 3,000 ft accordingly. The T/D is calculated somewhere between ALESO and ROTNO and we always try to initiate the descent app. 4 miles before the blue arrow. The maximum speed of 180 kt at or around D9 BIG is maintained, however the AP is not able to lower the plane enough.

I have no idea how all these heights and speeds are calculated in the system, but the flight plan is exactly as per the graphs initially before flight starts. There are some dynamical changes made in the route, which is understandable, but the question why the heights marked with * are not followed some times? I could not find a stable way for lowering the plane using the button also, because the AP is not following. I know that all these things can be easier explained by screen shots, however we did not take such at this time. I will make some during the weekend when I can run the SIM.

Hope someone from AS who knows the system in details can reply.

[FraPre 89]

Hi,

 

i hope, i understand this correct, you fly complete in the managed mode and the plane can not do it, to descend from the T/D and reach the FAF ALT 2500 ft without further intervention.

The T/D between ALESO and ROTNO is correct, i means, the first restriction is FL180 at ETVAX.

Real you have insert the wind data for the descend, and this can affect quite noticeably profile. The Aerosoft Airbus does not have this possibility, but you fly with real weather (and wind). The Profil in the Aerosoft Airbus is calculated without wind data.

For the Descend you can use the managed mode, but you must observe and switch between the AP modi for support and warranty the constraints and ATC Requirements.

In this video you can see, the pilot switch between the modi upon need and help out with the speed brake for reduce the airspeed.

 

Video

 

I´ve not problems with this method to fly from T/D to FAF and reach every constraints.

[Goshob 23]

Hi,

I may need to come back to the post, no matter that it seems to have no interest within the audience...

Reviewing the post above, watching the attached video and some other material concerning the subject, I can fully agree that the wind is affecting the flight's heading and the speed. At the same time there are very low possibility for it to affect the height. A320 and all other propelled planes are not balloons or planners, which are using the temperature inversions and different air flows during their flight. This is at least what the major course of physics teaching the students.

Based on the above and repeating once again that I have no idea what mathematics was included in AS  SIM, I strongly feel that there might be some small, but awful mistake in the flight plan, which  creates all the hassle. I thought it might be useful if some manual correction of vertical speed is applied at the final stage of the flight where the plane definitely is higher than the requirements of the chart ( FAF ALT 2500 ft ). On another hand the question why the plane stays above the height marked with * in the plan remains unclear.

Hope some comments from more experienced may come.

 

P.S. Sorry, I am unable to attach any screenshots now because all my weekend was occupied with other issues, but will be done soon.

 

[skelsey 103]

On 19/03/2017 at 7:07 PM, Goshob said:

Reviewing the post above, watching the attached video and some other material concerning the subject, I can fully agree that the wind is affecting the flight's heading and the speed. At the same time there are very low possibility for it to affect the height. A320 and all other propelled planes are not balloons or planners, which are using the temperature inversions and different air flows during their flight. This is at least what the major course of physics teaching the students.

 

Sorry, but your understanding here is flawed.

 

Wind will not affect the rate of descent, but it most certainly will affect the angle of descent, and this is what is significant.

 

If you have a tailwind, your ground speed will be increased. Let's say that you start off at A at FL240, and you want to get to point B, 63NM away, at 6000ft. That's an 18,000ft change of height in 63NM -- very approximately a 3 degree path.

 

If you are flying at 420kt TAS and there is no wind, your ground speed will also be 420 kt. It is easy then to establish that it will take 9 minutes to travel from point A to point B.

 

To lose 18,000ft in 9 minutes we need to descend at 2000 fpm. Agreed?

 

OK. Now let's say that our TAS is still 420 kt, but now there's a 60 kt tailwind, making our ground speed 480 kt.

 

How long will it take to travel the 63NM from A to B now? Easy: 480 kt is 8 nm per minute, so 63/8 = 7.87, so just under 8 minutes.

 

Our rate of descent is still 2000 fpm (because the aeroplane doesn't care about its ground speed - it will continue to perform just as it did before.)

 

What altitude will we be at when we reach B this time if we start our 2,000 fpm descent at A just as we did before?

[Goshob 23]

Hi,

Thank you for the explanation. I fully agree with your thoughts for the affect of the wind on angle and rate of descent. It is a well known physical low that S=V*T and we have to accept it no matter if we like it or not. That is the reason why in some cases my plane ends up higher than necessary.

The main question, which I was trying to ask in several posts already is how such situations are handled practically? Is there no any corrections made by the flight computer when wind is observed?

One more thing, the calculation when there is a pure tail or front wind are easy, but what happens if the wind is from the side? This is the most common case and hopefully everyone may imagine what kind and amount of calculations have to be made for determining the components, which are acting on the plane. And again the question, how is this handled in real life?

[skelsey 103]

2 hours ago, Goshob said:

how such situations are handled practically? Is there no any corrections made by the flight computer when wind is observed?

 

As mentioned above -- the main answer is the same as any time that the automation isn't giving you what you want in managed mode -- go to selected modes (like OP DES or, rarely, V/S). You can also adjust the speed (unless ATC have issued restrictions) -- higher speed will result in a steeper descent profile (drag increases with the square of speed whereas Green Dot represents the best L/D ratio, i.e. the speed at which the aircraft will glide the furthest). If you are very high and/or you cannot increase the speed any further you may need to add some drag (i.e. speedbrake), but a more efficient solution is to anticipate the problem early (as in - before TOD) and potentially start down before (or, in the case of a headwind, after) the FMGC has computed (if you're putting the speedbrake out, you're essentially throwing away all the energy you put in to the aircraft earlier by staying high with the engines at cruise thrust -- a bit like turning the heating in your house on full for two hours, then realising it's too hot, turning it off and opening all the windows: it would have been more efficient to on turn the heating on for one hour and not have to open the windows in order to throw away all the energy you put in that you now don't want).

 

I should add that all of the techniques above are very much real life ones as well -- even if you have put the winds in to the FMGC, the chances of the forecast wind matching up exactly with the wind experienced by the aircraft in real life are virtually nil, plus add some other atmospheric and aeroplane vagaries (no two aircraft are quite exactly the same, if you have to use the anti-ice during the descent that will increase the idle speed of the engines and therefore reduce the rate of descent, etc etc etc) and the FMGC computed descent profile very much becomes a "best guess" rather than the definitive answer. This is why the FMGC, in managed descent with managed speed, retains the ability to vary the speed from the computed target slightly in order to allow it to correct for minor variations, but if the wind is significantly different then pilot intervention will be required to regain the path. Likewise (and not saying this is necessarily the case with this particular arrival, but they certainly exist) the FMGC cannot rewrite the laws of physics: there are some STARs and approaches which are designed in such a way that the profile is simply unachievable in managed mode.

 

The FMGC is good, but it's not infallible and a human pilot monitoring and tweaking the descent can almost always do a better, more efficient job.

 

3 hours ago, Goshob said:

One more thing, the calculation when there is a pure tail or front wind are easy, but what happens if the wind is from the side? This is the most common case and hopefully everyone may imagine what kind and amount of calculations have to be made for determining the components, which are acting on the plane. And again the question, how is this handled in real life?

All you need to know really is your ground speed (which is computed by the aircraft and displayed on the ND). However, calculation of head/tail/crosswind components is bread and butter for pilots.

 

If the wind is at 90 degrees to your flight path then, of course, there will be no change to your ground speed (although, of course, to maintain tracking you will have to turn the aircraft in to the wind somewhat to lay off the drift, which in turn will result in a headwind component, but we're starting to get in to the realms of technicalities here). If, as you rightly say is normally the case, there is some element of crosswind and tail/headwind, then you can use a rule of thumb to estimate the components which is close enough for for flying work -- the "rule of sixths". For each 10 degrees off the nose, take a sixth of the wind speed as crosswind component (60 degrees or more take all of it). So for 20 degrees off the nose then 2/6 is crosswind, 30 degrees off the nose take half and so on.

 

The same formula works in reverse for head/tailwind components: on the nose take all of it as headwind, 10 degrees off the nose take 5/6 as headwind, 20 degrees take 2/6 and so on (and likewise for tailwind).

 

Greater precision can be achieved with something like a flight computer (more commonly seen in basic flight training and GA flying, but I know airline pilots who still carry a whizz wheel with them in their flight bag!), but this isn't really necessary on a practical level.

 

As a good rule of thumb -- height to lose x 3 = distance in NM (i.e. if we assume the airfield is at sea level and we are at FL360, 36 x 3 = 108NM) (slightly steeper than 3 degrees) or distance to run x 3 = the height you should be at any particular point during the descent (so at, say, 40nm to run = 40 x 3 = 120 = 12,000ft) (slightly shallower than 3 degrees). Add a bit to allow for deceleration -- about 10NM is a good start -- and add (or subtract) a bit for the average head/tailwind component you anticipate throughout the descent (add about 2NM per 10 kt of tailwind, subtract for a headwind). This is a quick, rough calculation that you should do for every descent to sanity check the FMGS numbers -- and don't forget to monitor the descent continuously throughout using that range x 3/height x 3 rule of thumb mentioned above and intervene if necessary. Remember that the descent is not just about losing height, it is about energy management and so speed comes in to the equation as well - if you are at 10,000ft 35NM out at 250 kt IAS you are roughly on profile, but if you are at 10,000ft 35NM out at 350 kt you are high because you will need to level off at some point to reduce the speed!

 

The FMGS is at the end of the day a dumb computer: it cannot anticipate in the same way as a human pilot can and if left unchecked it will quite happily add thrust during what it thinks is a shallower part of the profile, only to get high and subsequently demand MORE DRAG. As I say -- 99.9% of the time a human can do a much, much better job

[Goshob 23]

Hi Skelsey (Simon),

Thank you for the explanation! Much appreciated. This is actually the type of discussion, which I was trying to start here. Some people might find it boring or qualify it as very much theoretical and useless, but I strongly feel that it has its value. What I was trying to say many times to my younger colleagues is that operating any computerized unit is not only perfect knowledge of basic setting and adjustments of the knobs. There is lot of human knowledge behind and you very properly mentioned that in 99.9% of the cases a human can do much better job than the most sophisticated machine.

Anyhow and coming back to the subject, kindly advice if I may ask for some more clarification questions. I have to admit that flying is my hobby only and there are many things, which I need to learn still.

Thank you!

[The Dude 6537]

I would love to have a Skelsey Info Corner here in the forums but as he joined another team that is not possible anymore. 

 

I value Simon's inputs here very much but do consider that this is an AS support section of the forum and this topic has been effectively hijacked. 

 

Please do continue this conversation for the benefit of everybody reading here but do so in the general section of the AS airbus forum. 

 

Thanks

 

[skelsey 103]

6 hours ago, Goshob said:

kindly advice if I may ask for some more clarification questions. I have to admit that flying is my hobby only and there are many things, which I need to learn still.

Thank you!

Of course you may (though, as Frank says, General Discussion may be a better location). Only too happy to help where I can!

[captanskywalker 1]

Thanks for hijacking this post and taking it away from the help I needed...... nothing here resolves or even comes close to my issue, no offence to any but yeah not cool...

[DaveCT2003 2553]

31 minutes ago, captanskywalker said:

nothing here resolves or even comes close to my issue

 

 

The thread is still open, and I believe we're still waiting for your screen shots.

 

 

[Goshob 23]

7 hours ago, captanskywalker said:

Thanks for hijacking this post and taking it away from the help I needed...... nothing here resolves or even comes close to my issue, no offence to any but yeah not cool...

I sincerely do appologize for hijacking your post! Starting writing in it was with a completely different intention to where it went, simply because I was having a similar issue.

Sorry once again 

---

---

[captanskywalker 1]

On 23/03/2017 at 8:19 PM, Goshob said:

I sincerely do appologize for hijacking your post! Starting writing in it was with a completely different intention to where it went, simply because I was having a similar issue.

Sorry once again 

---

---

Thanks I do appreciate that!

 

On 23/03/2017 at 1:13 PM, DaveCT2003 said:

 

 

The thread is still open, and I believe we're still waiting for your screen shots.

 

 

I have had pc issues hope to have these up very soon, not sure what help it will be as I have said only with the IAE I have the CFM setup the same way during flight and no issues