FBW A32NX Autothrust/Levers

Hello all, after looking around a bit I feel I have a question that hasn’t been answered anywhere yet, if so, apologies.

I recently updated my fbw a32nx (Development version), and suddenly, takeoff is a $#!t show. I have also recalibrated my hardware (TM TCA o.pack) in windows, in game, and from the FBW efb, which all appear to be working correctly.

My issue is, with eicas T.O. all green, and properly configured like I’ve done hundreds of times before, as I advance the throttles, once I reach the TOGA gate, auto thrust engages, the thrust levers go (in game) back to IDLE and the autobrakes and spoilers engage.

In trying to avoid this, I’ve attempted T/O from the flex detent and even the climb detent, and as soon as I leave the ground, A.Floor is triggered, and well, if you know, you know. Especially embarrassing on vatsim lol.

Has anybody else experienced this? Am I just missing something simple, or something new?

Everything else works fine, and throttles on all other planes work perfectly.

Thanks in advance for the help.

Did you set the ap target speed? Default is 100knts which is surely below stall speed

The AP target speed always disappears (three dashes) once I enter my vspeeds into the box. Ive always have left it in this managed mode and never had any issues.

This is weird, because TOGA is a Manual thrust. Anytime the throttle reaches MCT/FLX or TOGA detent, the Autothrust should have been disengaged and go into manual thrust.

There must be something that made your initial pre-departure takeoff done differently. I know you said you’ve done the exact same thing as before, but maybe doing so is what’s causing the problem since it might be expecting you to do it differently now?

Just check on something, flight model. make sure it’s still modern and not sitting at Legacy for some weird reason.

Also, if you “updated” the fbw a32nx aircraft, you might still be having a lot of junk files from the previous version which might have affected it. Try to delete everything fbw a32nx from the community folder as well as the one above it in the packages/work folder. Then install a fresh new version instead. Hopefully it’s clean enough from any junk files that might have affected your takeoff.

Other thing you might need to check is Assistance settings. Make sure it’s still set to True to Life as a preset, and everything in it is set to Hard. And check your control settings, sometimes you might need to reset it to default, and make sure you don’t have duplicate bindings like throttle commands being bound to multiple inputs, which might cause your RTO to engage on take off.

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Well something changed then. Before now, takeoff was simple, thrust levers to 40%, stabilize, then thrust levers all the way forward. Auto Thrust would automatically engage, and off I went. At 1500ft: AP on, thrust levers to climb detent, flaps up, cya!

I will try cleaning out FBW tonight. I did double check that the marketplace version is not installed. I have a feeling its something in the flypad, I only checked the detent as I was on a short vatsim flight the last 3 times.

You must have a FLEX TO TEMP value entered in the PERF TAKE OFF screen before you take off in the flex detent. If you don’t do this, auto-throttle will not engage.

If you leave the FLEX TO TEMP field empty, you must take off in the TO/GA detent.

That is very understandable. I always enter 0 for that value. Either way, its still weird to immediately be in a.floor when leaving the runway at v2.

I wouldn’t enter zero. That’s a real number as opposed to null/NaN.

Either leave blank or enter a proper calculated number. From what I’ve seen online, the calculation for FLEX TO TEMP is:

OAT + [ISA − ((ELEV ÷ 1000) × (1.98 × −1))]

There’s a cool MCDU emulator I found online and it explains many of the fields:

Awesome thank you.

As im going through the MCDU emulator, I saw that is NOT recommended to do takeoff at Flaps 1. This is something I started doing the last 3 flights, only because with the few options for flap settings, i felt 2 might be realistically excessive for good weather takeoffs. Every single flight before that was flaps 2…this may explain my problem. Flaps 1 is possible if you use “1+F” for the PERF setting, but ive never heard of it.

I also read that if you pull the sidestick all the way back, it initiates a.floor automatically, and with the lower flaps setting I most definitely noticed it took far more movement of the stick to get off the ground, and that is likely another cause.

Now, to figure out why the throttle of the sim goes back to idle when moved to 100%…

How does the MCDU recommend against Flaps1 for takeoff? Flaps1 takeoff is standard for the Airbus.

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The MCDU doesn’t actually recommend against it, the MCDU tutorial suggested above is what recommended against flaps 1. Something to the tune of possible dangerous combos of performance factors and not having enough room for error. It strongly recommends always using 1+F for the Flaps setting on the PERF page when using flaps 1, something to the tune of preventing automatic flap retraction (didn’t know this existed).

Well I think I figured out the problem. A.Floor issue caused from throttle issue, throttle issue caused by my physical throttle having an issue.

I may have put to many cycles on this bad boy (TM TCA o. pack). It seems that whatever measures the throttle position is failing. After adjusting all possible settings, it seems it sends a signal that it is in the neutral pos. at one of either ends. So i can adjust it to either not have full throttle or not full reverse.

Note, the first thing i did when I got the throttles was remove the gates for the detents and tighten the resistance all the way, as I knew I wanted to use them on more than just the Airbus, and those gates were very deturring to setting specific power. Not sure if this is a cause, but looks like its time for for the Boeing version :slight_smile: I’ve got just under 200 hours on these throttles/stick.

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Ah well if you set Flaps 1 for takeoff, the MCDU automatically interprets this as 1+F. I’m not exactly sure how to override this and force it to just Flaps 1 so I don’t think you need to worry.

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Very interesting. But also very incorrect.

The calculation for flex temp? Is there another one? It hasn’t been easy to find.

Yes, the calculation for flex temp. It isn’t a simple equation like that. Currently, there isn’t one available for the A320NEO.

I just put 58 degrees on all my flights… :rofl: It’s not like the FLEX TEMP is “actually simulated” (yet) anyway.

Flex temp is correctly simulated in the A32NX (even though there isn’t a calculator for it yet).

Ohh I see… Since I read this part from the Preparing the MCDU - FlyByWire Simulations Documentation page. I just assumed that it’s not simulated since it says there’s no public information on it. Since if it were simulated, someone would have “reverse-engineer” a Flex Temp calculator from it already. But if the FBW team says it’s simulated, who am I to dispute that… Hahaha :sweat_smile:

Unfortunately, A320neo performance data for FLEX temp performance calculators alongside other various tools are not publicly available and are guarded by Airbus. For the purposes of simulation, it’s important to note the following:

Typically, Flex temps are above ISA+29C (44C at sea level) and above current temp, but no higher than ISA+55C (70 C at sea level). Usable Flex temps are from 45 C (or current OAT if it is higher) to 70 C.

Additionally, a decent rule of thumb for simulation purposes is to use a lower number if heavy or on a short runway and higher for the opposite.