B307 Autopilot Lateral Nav Aggressively Banks Aircraft and Overcorrects at High Altitude

[NixonRedgrave]

Thank you for using the Bug section, using templates provided will greatly help the team reproducing the issue and ease the process of fixing it.

2 tags are required: One for platform, and one for aircraft.

Are you using Developer Mode or made changes in it?

No

Have you disabled/removed all your mods and addons? If the issue still occurs with no mods and add-ons, please continue to report your issue. If not, please move this post to the Community Support section.

Yes

Which aircraft are you reporting an issue about? (Please also add the proper tag for it)

Boeing 307

Brief description of the issue:

When at high altitudes, the autopilot’s lateral navigation is turns the aircraft way too aggressively, overshoots its intended heading and then overcorrects by aggressively banking the opposite direction. It cycles like this, losing altitude until the aircraft is out of control and spinning. This happens in both HDG and NAV modes.

Provide Screenshot(s)/video(s) of the issue encountered:

Detailed steps to reproduce the issue encountered:

Climb to 17500-18000’ by hand. Set a heading for the autopilot to follow that deviates from the current heading. Engage heading hold and observe the aforementioned behavior.

PC specs and/or peripheral set up if relevant:

N/A

Build Version # when you first started experiencing this issue:

0.1.9

---

For anyone who wants to contribute on this issue, Click on the button below to use this template:

Do you have the same issue if you follow the OP’s steps to reproduce it?

Provide extra information to complete the original description of the issue:

If relevant, provide additional screenshots/video:

[NixonRedgrave]

Do you have the same issue if you follow the OP’s steps to reproduce it?

Provide extra information to complete the original description of the issue:

Here’s a video of the aircraft falling on its side when the heading selector is altered. The aircraft didn’t survive to swing back the other direction as it lost control too quickly. However, it illustrates the overall issue with the AP at altitude.

If relevant, provide additional screenshots/video:

Heading Change at Altitude - Create and share your videos with Clipchamp

[OrigBullethead]

I have never gotten the 307 above above about 8-10K (and that only starting on the runway—NEVER from cold and dark due to instant Vmc rolls). And I’ve only flown it with the gyropilot instead of the modern autopilot. But I can say that the gyropilot is broken, no doubt because the modern AP controller is still there in the same cockpit with the gyropilot. And, in fact, the gyropilot is still there in the center of the panel even when you have the 530/430 stack.

I mean, look at this mess. When NOT having the 530430 stack, there’s a toggle switch in the middle of the ADF and CDI gauges to toggle between VOR/LOC and GPS, despite this switch ONLY being present when GPS is NOT installed, because the GPS occupies the space where this switch is. And, of course, you can see the modern AP is there with or without the Garmins.

And WITHOUT the Garmins, the gyropilot’s gyro compass doesn’t move at all. It’s stuck reading north. You can move the heading bug all you want but, because the gyro compass part of the gyropilot is broken, it will never follow the desired heading. It does follow bank and pitch inputs, however.

[Jummivana]

The test team expects this to be user error, would you mind trying again? You might be hitting ALT and “NOT” accelerating to cruise speed and as such the plane enters a bank this will automatically decrease airspeed and you are already in the white arc and the aircraft stalls. AP does what its told and it can be told to turn to a heading at a really low airspeed.

[NixonRedgrave]

I figured this would be the case. I had made this video after the aircraft had turned into a headwind and slowed dramatically, however it did this same behavior with 140 indicated airspeed moments before making this video, too.

I will see about making another video.

How about someone on the team fly the aircraft, by hand, to 17500’ set a heading 90° to their current heading and engage the AP with HDG mode and make of video of how that goes.

EDIT:

Here is an other video. Aircraft is at ~140 KIAS and it cannot go faster than this at this flight level. The AP is, presumably in ROL mode (not indicated) with ALT Hold engaged at 17500’. I’ve set a heading that is nearly 180 degrees to the current heading. Observe how aggressively the AP banks the aircraft and immediately loses control.

307 AP - Create and share your videos with Clipchamp

There is no “White Arc” on this air speed indicator:

If this aircraft is not meant to cruise at this altitude then its specifications and documentation need to be altered to reflect this fact.

[NixonRedgrave]

@NixonRedgrave

If this aircraft is not meant to cruise at this altitude then its specifications and documentation need to be altered to reflect this fact.

To reinterate:

The Marketplace B307 page states: “…a service ceiling of 23,800 feet above sea level, a cruise speed of 222 miles per hour, and a top speed of 250 mph.”

The Marketplace and My Hangar Specifications page both state:

• Max Speed: 250 MPH (217 kn)
• Ceiling: 23,800 ft (7,254 )
• Cruise Speed: 222 MPH (193 KN)

Documentation states: “Normal cruise speed is 222 M.P.H. (at 19,000 ft)”

The flight featured in second posted video is at 17,500’ at ~140 MPH with the power levers firewalled and RPM set to METO – the engines have nothing more to give.

[NixonRedgrave]

After reviewing this extensively and trying, yet another flight, it appears the issue is linked to the attitude indicators being caged/uncaged.

If the indicators are caged, the aircraft will spin out of control. If uncaged it will not.

The issue isn’t one of airspeed, but of the instruments’ states interfering with the AP’s function.

It would be helpful if there was a tooltip that indicated their state when the knobs were rotated. I don’t use tooltips, so I can only assume that I’ve been inadvertently caging them when operating the AP, which isn’t easy for me to have to admit to.

[AquaOrc33481746]

Do you have the same issue if you follow the OP’s steps to reproduce it?

Provide extra information to complete the original description of the issue:

If relevant, provide additional screenshots/video:

Gyro compass cannot be uncaged if starting cold and dark. Is only uncaged if starting on runway.