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aircraft suddenly pitches up when crossing runway threshold


prof_laser

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OpenBeta 2.7.1.71390

 

I am on a short final (Al Minhad RWY 27) after a mission. From the overhead break, turning short final. I am on a stabilised approach. When crossing the runway threshold, suddenly the nose of my aircraft pitches up, without me changing any inputs.

 

I have repeatedly ran into this bug. It does not happen every time and is hard to reproduce. Today it happened at the end of a 2 hour mission, so I cannot add a track replay. Instead I am providing a video recording and my trimmed tacview of the bug. It does not necessarily happen after OHBs, but also on straight-in approaches. From what I could observe, it tends to happen after long missions. It happened to me in Caucasus and PG, on at least three different airfields with different weather conditions. It happend to at least four A-10C pilots in our wing.

 

I talked to a former member of the 476th, and he said that this bug was happening a few years back, then disappeared after it apparently got fixed. Now it seems to be back again, roughly at the time that 2.7 was published.

 

A-10C sudden pitch up on final.zip.acmi

 

Please apologize the language in the video.


Edited by prof_laser
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My bet is leftover wake effect from -1 landing ahead of you.  As -2, adjust your aim point 1000' down the runway (assuming you have enough runway of course).

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1 hour ago, prof_laser said:

OpenBeta 2.7.1.71390

 

I am on a short final (Al Minhad RWY 27) after a mission. From the overhead break, turning short final. I am on a stabilised approach. When crossing the runway threshold, suddenly the nose of my aircraft pitches up, without me changing any inputs.

 

I have repeatedly ran into this bug. It does not happen every time and is hard to reproduce. Today it happened at the end of a 2 hour mission, so I cannot add a track replay. Instead I am providing a video recording and my trimmed tacview of the bug. It does not necessarily happen after OHBs, but also on straight-in approaches. From what I could observe, it tends to happen after long missions. It happened to me in Caucasus and PG, on at least three different airfields with different weather conditions. It happend to at least four A-10C pilots in our wing.

 

I talked to a former member of the 476th, and he said that this bug was happening a few years back, then disappeared after it apparently got fixed. Now it seems to be back again, roughly at the time that 2.7 was published.

 

A-10C sudden pitch up on final.zip.acmi 169.04 kB · 2 downloads

 

Please apologize the language in the video.

 

 

I experienced this about 3 times as well.  Always happens at exact spot and only with A10C-II.  No plane in front of me.  Too consistent to be considered random weather effect.


Edited by Taz1004
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I've got about 15 2~hour long missions in the A-10C-II so far and have never experienced this issue. What are the turbulence values in these missions? Some creators set an insanely high turbulence value which can cause issues on landing. 

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9 hours ago, Puma said:

My bet is leftover wake effect from -1 landing ahead of you. 

I was leading the flight back home, so -1 was behind me. There were no other aircraft at that airfield.

 

3 hours ago, Nealius said:

What are the turbulence values in these missions?

Turbulence value was set to 3, I believe.


Edited by prof_laser
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I saw this once on Syria so far (A10CII), and my friends were watching my perfectly smooth approach to land when the nose just went to the stars with no input or changes from me.

 

I tried the emergency disconnect of the elevators which didn't help.

 

I tried the manual reversion switch, and after switching it back to normal, the plane flew just fine again.  Not sure it helped, and this was 40-50 seconds after the problem began as I was trying and checking for any indication of what was wrong (no caution lights).

 

However, when it happened, I had full forward on the stick and the nose would barely descend.  I put flaps up and that didn't help as I recall.

 

It was also a 1.5 hour long mission I didn't save a track of as it happened at the very end.  It was a liberation mission on Persian Gulf, landing on 31L at Al Dhafra.

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I tried to trigger the bug in a test mission, but I am unable to actually trigger it at will. The only track files I have that show the bug are those where I landed at the end of very long missions. That probably won't help because of desync.

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Oh! This kept happening to me too during the Operation Persian Freedom campaign. Funnily enough, the only time it's happened to me is also after long missions so making a track may be tough. But maybe the mission length is somehow a factor in it?

 

It usually happened a matter of feet from the runway in my case, about to make a lovely touch down then it would suddenly just float. I wouldn't even say pitch up, it just sorted of started of floating, as if someone had pumped it full of helium.

 

Sort of glad to see I'm not the only one.

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  • 2 weeks later...
  • 2 weeks later...

I have also seen this a few times recently.

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  • 2 weeks later...

This happened to me yesterday too. I remember this bug from the legacy A-10C: a pitch down was felt after passing under a bridge or under another aircraft. Then when landing at the threshold the pitch did reset, so a strong pitch up was felt there. It was fixed years ago.

 

I had no time to check whether it is the same bug, but it definitely felt the same. A few threads from that time:

 

 

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  • 2 months later...

Bump, still happening. Happened several times during Operation Persian Freedom campaign when landing on Al Minhad airbase.

It might have something to do with trim. Before it happened it felt like the A-10 was ignoring trim. Full nose up trim was not enough to keep it on on-speed AoA, had to pull back the stick to keep the nose from dropping when going at 130 kts. When about to touch down to the runway the nose suddenly shot up, like the full nose up trim was suddenly activated that the plane was ignoring before that.

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It happened yet again. Now I'm reasonably sure it has to do with trim somehow being ignored. While trimmed properly during landing, the nose suddenly started to drop. Anticipating this bug, I did not increase nose up trim but instead held the stick back. When about to reach the runway the nose started rising as last time. I let go of the stick and voila, the aircraft was nicely trimmed for on-speed AoA again. I don't know if it's related, but ILS was on.


Edited by gachatar
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I have also experienced this a couple times in dozens of flights, under very similar conditions (mission file).  I support your theory that it relates to trim, but have no conclusive evidence to add yet.  100% confident there is an issue in here somewhere though.

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  • 2 weeks later...
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I've seen this a few times over the past couple of months, but don't have any track files available unfortunately.

At least once it happened in Single Player at the end of a circa 2 hour long mission, and I'm pretty sure that just prior to landing, as I was coming in on a 10 mile final approach, I had to apply an unusual amount of nose up trim in order to get the A-10C II to fly on glideslope without too much manual input. Just before touchdown, it seemed as if all that nose-up-trim was suddenly applied and I had to counter it with a lot of forward stick.

On 11/3/2021 at 12:07 PM, gachatar said:

I don't know if it's related, but ILS was on.

In my case I'm pretty certain it was a non-ILS-approach and my ILS wasn't even powered; I assume ILS has nothing to do with it. 😉

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