not a bug ATFLIR breaks Autopilot

[Chaffee]

Hello,

This is my first bug post, and look, I'm a n00b, so maybe there's some bizarre, undocumented, Byzantine procedure here, but I don't think so.

Hot start. 4x MavFs and ATFLIR.

Master Arm on. A/G Mode. ATC active.

GMT on RDDI. Mavs on LDDI. HSI on AMPCD: box SEQ1; box AUTO (OSB 15 and 16).

Select CPL on UFC

Select ATFLIR on AMPCD and make SOI with SCS aft. Cycle INR to Scene to AUTO with SCS aft.

Autopilot quits with Master Caution notification as soon as AUTO mode is selected for ATFLIR.

"So," I thought, "maybe the F-18 Autopilot sucks. Bummer."

So, I did some testing, and here's the thing:

Nothing I do ever allows me to rebox "Auto" in the HSI. I can reset the entire jet back to Nav mode, turn off the ATFLIR, clear the A/P completely with the paddle, etc.( To be fair, I haven't ejected the actual TGP from the ship).

Still can't box "Auto" to get CPL to appear on the UFC. If I try to enter any kind of Autopilot mode, say "BALT," I get a Master Caution "AUTOPILOT" on the left DDI.

None of this behavior has come up on any search, in this forum or elsewhere. None of this behavior is documented in any official or unofficial documentation.

I can replicate this behavior 100% of the time, and I bet you can too.

So, what's up? All of this made sense as some kind of F-18 bad-design limitation from McDonnell-Douglas, but the perma-break of the auto-pilot makes no sense unless somehow the ATFLIR is shorting the flight computer, which would be a major failure.

Thanks for reading. Let me know if I'm missing something, but this system behavior is beyond bizarre.

 

Edited March 10, 2024 by Chaffee

[Muchocracker]

You're overriding the waypoint selection and the autopilot by actioning the TGP into an AUTO track. Any designation source will do this. The whole system revolves around having one or the other as the primary selection.

You have to undesignate the SPI in the HSI to reset everything and use auto sequence again. Turning off the TGP is not going to do that. Nor is changing master mode

Edited March 10, 2024 by Muchocracker

[Chaffee]

9 minutes ago, Muchocracker said:

You're overriding the waypoint selection and the autopilot by actioning the TGP into an AUTO track. Any designation source will do this. The whole system revolves around having one or the other as the primary selection.

Okay, so why is the autopilot gone forever?

I literally unpowered designation sources, like the Mavs and the TGP.

Does the jet have a one-way logic gate that says "once you've designated something once, autopilot is offline for the rest of the flight?"

That's a serious question, because, if so, it's a major operational weakness to the extent that I'll ditch the pod permanently.

Secondary question: if designation is overwriting a waypoint in CPL mode, why does that affect the BALT A/P mode, which doesn't require a waypoint?

Edited March 10, 2024 by Chaffee

[Muchocracker]

Again. Just "turning it off" doesnt do anything because the designation is still there. Remove the designation and it will allow you to select a waypoint and turn the auto sequence/cpl autopilot back on again.

 

You can't do both of these things at the same time it's just not how the hornet works

Edited March 10, 2024 by Muchocracker

[Chaffee]

1 minute ago, Muchocracker said:

Again. Just "turning it off" doesnt do anything because the designation is still there. Remove the designation and it will allow you to select a waypoint and turn the auto sequence/cpl autopilot back on again.

 

You can't do both of those things at the same time it's just not how the hornet works

 

Huh. Okay. So any designation with the ATFLIR eliminates all autopilot modes, whether or not they are waypoint dependent, until no designations are logged, irrespective of mode or the pod even being powered.

Thank you for this clarification.

I have one other request: This behavior doesn't appear to be documented in the autopilot section of the ED manual, which is where I looked first.

It honestly should be documented. Otherwise, there's no objective way to determine whether this behavior is intended. I'd recommend adding the sentence "Designating a target with the TGP will disconnect all autopilot modes until the target is undesignated."

[Muchocracker]

It does not disable all autopilot modes idk where you're getting this from. All of the other modes but coupled are still actionable 

[Muchocracker]

See. All of the other autopilot modes are still actionable and even some stay activated when the coupled mode is disabled. When you create a designation with any of the sources (rdr, tgp, helmet, hud, waypoint) it is dropping all of the waypoints out including the sequence and focusing on only the designation and providing steering cues for it.

To go back to the waypoint sequence you have to wipe that designation. Which can be done either by using the Undesignate/Nose Wheel Steering switch on the stick. Or by hitting the boxed TGT option on the top right of the HSI where the waypoint selection usually is. 
 

[Chaffee]

On 3/10/2024 at 12:57 AM, Muchocracker said:

It does not disable all autopilot modes idk where you're getting this from. All of the other modes but coupled are still actionable 

Again, thank you. Your earlier post was clear.

RE: your question about other autopilot modes, I got that from every attempt to re-establish autopilot (including BALT) on that flight resulting in a master caution A/P callout.

However, the issue resolved itself on the next flight without problem, so it was likely an unrelated issue (cockpit misclick, RAM going bananas, pilot confusion/overload, etc.).

I appreciate your time on this.

I'd renew my request for the following sentence to be added to the official manual in the section on "Coupled Autopilot Mode," page 150f: "Designating a target with the TGP will disconnect coupled autopilot mode until the target is undesignated."

Edited March 12, 2024 by Chaffee

[Tholozor]

26 minutes ago, Chaffee said:

"Designating a target with the TGP will disconnect coupled autopilot mode until the target is undesignated."

This isn't exactly true. While normal, WYPT-based coupled steering cannot be performed while a TGT designation exists (which is not exclusive to the use of a targeting pod), the Hornet's autopilot is capable of coupled steering to a TGT designation if the selected weapon provides an azimuth steering line (CPL ASL). Primarily, free-fall munitions such as the Mark 80 series general purpose bombs, Rockeye-series cluster bombs, and Paveway-series LGBs can all utilize CPL ASL.

[Chaffee]

1 hour ago, Tholozor said:

This isn't exactly true. While normal, WYPT-based coupled steering cannot be performed while a TGT designation exists (which is not exclusive to the use of a targeting pod), the Hornet's autopilot is capable of coupled steering to a TGT designation if the selected weapon provides an azimuth steering line (CPL ASL). Primarily, free-fall munitions such as the Mark 80 series general purpose bombs, Rockeye-series cluster bombs, and Paveway-series LGBs can all utilize CPL ASL.

Thank you. Super good to know and very interesting. Honestly, it's why I paraphrase my understanding of the process in a forum, because if there's a subtlety that's missed, someone is likely to be helpful and correct any assumptions or omissions.

(It's also exactly why I'd love to see this kind of thing documented in the manual).

This isn't a criticism of the current manual... I've used it to give suggestions to YouTubers making very good tutorials (but who nonetheless missed something in the official documentation).

Love the module. Love getting back into serious flight simming. Love the F-18 community in general.

[Muchocracker]

5 hours ago, Tholozor said:

This isn't exactly true. While normal, WYPT-based coupled steering cannot be performed while a TGT designation exists (which is not exclusive to the use of a targeting pod), the Hornet's autopilot is capable of coupled steering to a TGT designation if the selected weapon provides an azimuth steering line (CPL ASL). Primarily, free-fall munitions such as the Mark 80 series general purpose bombs, Rockeye-series cluster bombs, and Paveway-series LGBs can all utilize CPL ASL.

i'm aware, and i didn't mention this on purpose to not make things confusiing. It wasn't relevant to the issue at hand.

Edited March 12, 2024 by Muchocracker

[Chaffee]

On 3/12/2024 at 5:03 AM, Muchocracker said:

i'm aware, and i didn't mention this on purpose to not make things confusiing. It wasn't relevant to the issue at hand.

 

Nonetheless, both of you have changed my experience for the better. These target-point/autopilot interactions are gold -- completely changed the way I'm approaching LGBs for the better. Helped me understand how Mavs work differently.

It's very interesting how coupled autopilot needs a steering line to work with a target point. That's a useful understanding to have that fills the gap as to why it doesn't work with Mavs.

Thank you both!

Edited March 13, 2024 by Chaffee