[CHECKING] There might be a bug with the RALT and BALT autopilot modes

Hi guys,

I've been having a few strange issues with BALT and RALT auto-pilot modes since the last couple of updates.

The Hornet has a basic autopilot mode called heading hold. This mode is engaged by hitting the A/P push button and then the ON/OFF push button (UFC). Activating this mode will trigger the A/P advisory on the left DDI.

Additionally, if any of the A/P modes are engaged, decolonizing (removing the ':' ) will revert to heading hold.

My problem is:

Sometimes, selecting either BALT or RALT will trigger the basic mode instead of the selected mode. Additionally, choosing RALT outside the altitude limitations (above 5,000 feet) will also trigger the basic mode, which is not mentioned in NATOPS as far as I know.

Attached are two tracks showing that behavior.

The first track:

BALT works the first time I activate it. I deactivate it, pitch the nose down a bit and then try to use it again - it triggers the basic mode (A/P is shown on the left ddi). Then without any input from me, the plane levels up and the autopilot snaps to BALT. This is followed by a few additional activations of BALT from me, showing that it can activate in higher degrees of pitch than the time when it failed.

The second track:

Diving from 25K (you can speed up that part), I try to engage RALT above the altitude limitation and the basic mode is activated (can anyone confirm if that's the way it is supposed to work?).

Below 5,000 feet I try to activate RALT a few times and it fails, again and again, until it finally activates under 1,100 feet. (yes, the radar altimeter is on)

As you can see- every time it fails, no colon appears next to the selected mode.

BALT not activating.trk

RALT not activating.trk

you need a little deadzone for your stick

you need a little deadzone for your stick

How is that related to what I reported?

How is that related to what I reported?

BALT won't activate with Y-axis stick input present (sometimes?), so adding a deadzone of even 1 helps with this, because your joystick might not be perfectly centered all the time.

I didn't touch any of the controls while trying to activate the autopilot. The stick was not connected at that time. I used the keyboard to fly the plane.

This is something I encountered just recently but does occur for some of my friends as well. I made sure to double-check it before posting since I've never had a single issue with the autopilot since the release of the module.

There are two ways to activate heading hold that I know of. Missing some criteria for BALT \ RALT is the third way- and I want to know if that's accurate. I find it hard to believe the plane is designed to activate a different A\P mode than the one you choose.

In the second track, you can see me trying to activate RALT under 5k and it works only on the fifth (or so?) attempt.

I'm just wondering why it activated heading hold instead. Correct me if I'm wrong here, but if I try to activate RALT above 5k - nothing should happen. (under 5k is should just level on the altitude you are flying at)

My understanding is that there are only two ways to activate heading hold and that this is not one of them.

In the second track, you can see me trying to activate RALT under 5k and it works only on the fifth (or so?) attempt.

 

I'm just wondering why it activated heading hold instead. Correct me if I'm wrong here, but if I try to activate RALT above 5k - nothing should happen. (under 5k is should just level on the altitude you are flying at)

My understanding is that there are only two ways to activate heading hold and that this is not one of them.

Do you by chance have “auto trim” enabled? I thought ED was going to remove it, or made mention of something about it - but others have stated issues with this option enabled and figured it might be worth one of those “shot in the dark” or “outside the box” thoughts...

Cheers,

Don

I didn't touch any of the controls while trying to activate the autopilot. The stick was not connected at that time. I used the keyboard to fly the plane.

Never ever was able to get a autopilot to work using keyboard. Was this ever possible?

The aircraft is not truly centered while using keyboard as control rather than proper joystick.

Never ever was able to get a autopilot to work using keyboard. Was this ever possible?

 

The aircraft is not truly centered while using keyboard as control rather than proper joystick.

It happens regardless of the way I use to control the plane. I noticed it when using my stick, and tried to replicate using the keyboard to make sure it is not related to my stick in some way. When I use the mouse to choose the A/P mode I make sure the plane is steady and my hands are not touching any of the controls.

@daarseth no, auto trim is not enabled.

My question is - it seems like if BALT or RALT can't work the plane goes to heading hold instead, which doesn't make sense and is not mentioned anywhere in NATOPS. Is this the way it should work?

Also, were there any changes to it recently?, because I've never had a single issue with it until now.

My question is - it seems like if BALT or RALT can't work the plane goes to heading hold instead, which doesn't make sense and is not mentioned anywhere in NATOPS. Is this the way it should work?

Also, were there any changes to it recently?, because I've never had a single issue with it until now.

No, the aircraft should not go into ATTH if BALT or RALT is not able to be selected due to being outside parameters. Haven't experienced anything like this on my side, will get another go in today it seems - so will check back in if that changes - but yesterday flew for a bit and didn't experience anything like this at all. Assuming all repair tool runs have been done, etc?

Cheers,

Don

Using the latest update here and all autopilot functions ATTH, HSEL, BALT, RALT are working as intended.

No, the aircraft should not go into ATTH if BALT or RALT is not able to be selected due to being outside parameters. Haven't experienced anything like this on my side, will get another go in today it seems - so will check back in if that changes - but yesterday flew for a bit and didn't experience anything like this at all. Assuming all repair tool runs have been done, etc?

 

 

Cheers,

 

Don

It's not ATTH (which is a different mode and will trigger a different advisory), it's heading hold, which is activated by selecting A/P and then the ON/OFF push-button.

It's not ATTH (which is a different mode and will trigger a different advisory), it's heading hold, which is activated by selecting A/P and then the ON/OFF push-button.

HSEL is set by the toggle switch to the top right of the AMPCD. Certainly shouldn’t select that mode on its own either. Just tried all variations on my side - worked just fine, as intended.

Cheers,

Don

Agreed - BALT is very finickity. Over 10000ft, baro altimeter on, AP engaged with BALT, the colon is intermittent, though you can see AP is indicated on the Left DDI, and gently increasing pressure on the stick Y axis will cause a 'jerk' in the plane when the AP is disengaged to allow human input. Track attached.

BALT ap indication.trk

HSEL is set by the toggle switch to the top right of the AMPCD. Certainly shouldn’t select that mode on its own either. Just tried all variations on my side - worked just fine, as intended.

 

 

Cheers,

 

Don

Daarseth, he's not talking about HSEL, he's talking about another autopilot mode which is not on the UFC list, heading holding, the basic autopilot mode. If I understood correctly, while with HSEL you can select the heading you want and basically steer the aircraft through HSI controls, when you hit the A/P button below the HUD and then the ON/OFF button, the autopilot will engage, keeping the aircraft on the heading it's on, but will not do anything else than keeping that heading.

Daarseth, he's not talking about HSEL, he's talking about another autopilot mode which is not on the UFC list, heading holding, the basic autopilot mode. If I understood correctly, while with HSEL you can select the heading you want and basically steer the aircraft through HSI controls, when you hit the A/P button below the HUD and then the ON/OFF button, the autopilot will engage, keeping the aircraft on the heading it's on, but will not do anything else than keeping that heading.

Ah, simply the on/off button. Yes I have noticed some behavior when depressing this - but never anything that I would have used or desired so it was limited a handful of actuations, as other functions seem ok.

Cheers,

Don

Daarseth, he's not talking about HSEL, he's talking about another autopilot mode which is not on the UFC list, heading holding, the basic autopilot mode. If I understood correctly, while with HSEL you can select the heading you want and basically steer the aircraft through HSI controls, when you hit the A/P button below the HUD and then the ON/OFF button, the autopilot will engage, keeping the aircraft on the heading it's on, but will not do anything else than keeping that heading.

Exactly- and thanks for helping me explain this.

The problem is I end up in heading hold under certain conditions when I choose another autopilot mode.

The easiest way for you to test this is to try and engage RALT above 5000 feet and see what happens. No colon will appear next to RALT, but 'heading hold' will be activated (but it will also make the stick a bit stiff like it does when you try to pitch when BALT and RALT are activated).

@Arctander - great track showing that issue :)

Exactly- and thanks for helping me explain this.

 

The problem is I end up in heading hold under certain conditions when I choose another autopilot mode.

 

The easiest way for you to test this is to try and engage RALT above 5000 feet and see what happens. No colon will appear next to RALT, but 'heading hold' will be activated (but it will also make the stick a bit stiff like it does when you try to pitch when BALT and RALT are activated).

 

@Arctander - great track showing that issue :)

"How" are you activating the RALT? I use a couple of programmable "keyboards" and I find sometimes it will cause the key to visually press on-screen, but it seems to fire fast enough that the game doesn't activate the press (needs to hold down for a fraction of a second). I've got my AP bound on my throttle and I haven't had any problems getting it to work.

In your case it could be either that, or it's firing twice in short order and turning it off again as soon as you get it turned on.

Exactly- and thanks for helping me explain this.

 

The problem is I end up in heading hold under certain conditions when I choose another autopilot mode.

 

The easiest way for you to test this is to try and engage RALT above 5000 feet and see what happens. No colon will appear next to RALT, but 'heading hold' will be activated (but it will also make the stick a bit stiff like it does when you try to pitch when BALT and RALT are activated).

 

@Arctander - great track showing that issue :)

Hitting A/P ON/OFF doesn't hold heading for me. Doesn't seem to do anything apart from showing A/P on the advisories.

"How" are you activating the RALT? I use a couple of programmable "keyboards" and I find sometimes it will cause the key to visually press on-screen, but it seems to fire fast enough that the game doesn't activate the press (needs to hold down for a fraction of a second). I've got my AP bound on my throttle and I haven't had any problems getting it to work.

In your case it could be either that, or it's firing twice in short order and turning it off again as soon as you get it turned on.

Like most cockpit switches- I use my mouse.

It's not a hardware issue (I checked that before posting. Watch my tracks to better understand this). As I explained before: engaging RALT outside the altitude limitations and BALT under certain conditions activates another autopilot mode. It should not do that.

@imacken in-game at the moment it will behave almost the same as ATTH.

@imacken in-game at the moment it will behave almost the same as ATTH.

Maybe, but it certainly isn't a 'heading hold' as you stated previously.

Maybe, but it certainly isn't a 'heading hold' as you stated previously.

It's called heading hold. That's the official name for it.

This is what heading hold does:

At this time the aircraft maintains the existing pitch attitude. If roll attitude is less than or equal to

±5° at engagement, the magnetic heading is maintained. If roll attitude at time of engagement is

greater than ±5°, the roll attitude is maintained. The pitch attitude hold reference can be changed with

pitch CSS to any value between ±45° pitch. The pitch attitude reference can also be changed with the

trim switch on the control stick at a rate of 0.5°/second. The roll attitude hold reference (if roll is

greater than ±5°) can be changed with roll CSS to any value between 5° and 70° of roll. The roll

attitude reference can also be changed using the trim switch on the stick at a rate of 2°/ second. The

magnetic heading reference (if roll is less than or equal to ±5°) can be changed, or initially set with roll

CSS. The roll trim switch also can change the reference magnetic heading.

This is what ATTH does:

Attitude hold is engaged by pressing the option pushbutton next to the option

display window displaying ATTH. Engagement is indicated by a colon in the ATTH option window.

At this time the aircraft maintains the existing pitch and roll attitude. The pitch attitude hold

reference can be changed to any value between ±45° with pitch CSS or with the trim switch on the

control stick (0.5°/second). The roll attitude hold reference can be changed to any value between ±70°

with roll CSS or with the trim switch on the stick (2°/second).

It's called heading hold. That's the official name for it.

 

This is what heading hold does:

 

At this time the aircraft maintains the existing pitch attitude. If roll attitude is less than or equal to

±5° at engagement, the magnetic heading is maintained. If roll attitude at time of engagement is

greater than ±5°, the roll attitude is maintained. The pitch attitude hold reference can be changed with

pitch CSS to any value between ±45° pitch. The pitch attitude reference can also be changed with the

trim switch on the control stick at a rate of 0.5°/second. The roll attitude hold reference (if roll is

greater than ±5°) can be changed with roll CSS to any value between 5° and 70° of roll. The roll

attitude reference can also be changed using the trim switch on the stick at a rate of 2°/ second. The

magnetic heading reference (if roll is less than or equal to ±5°) can be changed, or initially set with roll

CSS. The roll trim switch also can change the reference magnetic heading.

 

This is what ATTH does:

 

Attitude hold is engaged by pressing the option pushbutton next to the option

display window displaying ATTH. Engagement is indicated by a colon in the ATTH option window.

At this time the aircraft maintains the existing pitch and roll attitude. The pitch attitude hold

reference can be changed to any value between ±45° with pitch CSS or with the trim switch on the

control stick (0.5°/second). The roll attitude hold reference can be changed to any value between ±70°

with roll CSS or with the trim switch on the stick (2°/second).

Where has this info come from? I have not seen this ‘heading hold’ mentioned anywhere before.

Where has this info come from? I have not seen this ‘heading hold’ mentioned anywhere before.

Probably from NATOPS or another publicly available document for the Hornet I would guess.

The break down of the 5 autopilot functions for the F/A-18C Hornet are as follows:

The Automatic Flight Control System (AFCS), or just the "autopilot", controls the aircraft's flight controls to automate maneuvering. It is interfaced on the UFC via the A/P button.

The most basic mode of the AFCS is Control Stick Steering (CSS). CSS will attempt to maintain the pitch and roll of the aircraft without manual stick input. Roll input is dampened and pitch input is severely dampened. Forward or aft stick deflection beyond a certain point will disengage CSS. CSS is engaged manually by pressing the UFC ON/OFF button in the A/P menu and also engages with all other autopilot modes.

In the A/P menu, there are five main autopilot modes, toggled by pressing the option select button next to their window.

Attitude Hold (ATTH):

Maintains the current pitch attitude plus or minus 45° and the current bank angle plus or minus 70°.

Heading Select (HSEL):

Seers to the current heading selected by the heading select switch. The current heading can be viewed on the Horizontal Situation Indicator format.

Barometric Altitude Hold (BALT):

Maintains the current barometric altitude between 0 and 70,000ft.

Radar Altitude Hold (RALT):

Maintains the current radar altitude between 0 and 5,000ft.

Coupled Steering (CPL):

Maybe this is what you are experiencing when pressing the A/P ON/OFF button?

The CPL (coupled steering) option (if available) in the UFC

option display windows. When a pilot relief option is selected via the UFC a colon (:) appears in front

of the selected display and the selected mode appears on the DDI advisory display. If an option is not

available, it is not displayed. When the CPL option is selected on the UFC, the flight controls will

couple to that steering mode (in azimuth only).

^^ simply highlighting as there is really no direct documentation regarding the sole depression of the on/off button on the UFC when in the A/P mode ^^

A/P being displayed on the DDI simply means an autopilot mode is selected.

Cheers,

Don