F100 - ATS and Landing behaviour
-
Dear friends!
I've been flying your Fokker 100 and anso enjoying the experience. However, I would like to report a few issues and unexpected behaviors I have encountered during my flights.
Could you please look into the following points?
-
ATS Thrust Hunting and IAS Maintenance: The Auto Throttle System (ATS) struggles significantly to maintain the target Indicated Airspeed (IAS) during descent, approach, and at lower altitudes. There are large, continuous thrust variations (hunting), and the system fails to settle on the optimal power setting required for the desired speed.
-
AP Disconnect Pitch Down: When disconnecting the Autopilot (AP) on final approach, the aircraft exhibits a severe nose-down pitching moment. This requires an immediate and significant manual correction using the stabilizer trim to keep the aircraft on the glidepath.
I've recorded a short video regarding the points above: https://youtu.be/oYjhUXEw88M?si=rpanrQ58xDuZ0RR9
FMS Temperature and TROPO Inputs: The FMS occasionally rejects realistic temperature and Tropopause (TROPO) values extracted from my OFP/navlog, returning an "entry out of range" error message.
Low Cruise Altitude (CRZ ALT) Rejection: The FMS does not accept low cruise altitudes (e.g., FL080 for short local flights). I would like to ask: is this an accurate limitation of the real-world Fokker 100 FMS, or is it a software bug in the add-on?
FLCH Behavior: When using the Flight Level Change (FLCH) mode, I have noticed erratic speed variations and the application of engine thrust in situations where it seems completely unnecessary.
Thank you for your time and for the continued updates to this great aircraft. I look forward to your feedback on whether these are known issues being worked on or real-world quirks of the F100.
-
-
Hello there, I was about to write something very similar.
First of all, and most important to me, it is noticiable how hard it is for the aircraft to maintain a constant IAS speed, that being via the ATS or via the level change.
In ATS part, thrust takes to long to be applyed or removed, resulting in IAS droping to low from the selected IAS, and while accelerating it takes to long for it to decrease the power, resulting the IAS to extrapolate +/-15kts over the selected speed.I have also noticed the lack of agility from the aircraft to keep speed while in FLCH, that resulting in speeds al the way to 30kts below the selected altitude for descent (still need to try in climb mode).
-
CRZ LVL out of range was also something I've noticed, also still not knowing if that's a feature or bug, but I couldn't insert any Cruise Level below FL100.
I've tried to insert as FL080, 080, 8000, none worked.Discovered that while short hopping and flying IFR paterns to practice this new airplane.
-
Thank you for your feedback. Tuning of various AFCAS and ATS modes is something that we anticipate will be a continual ongoing effort throughout the lifespan of the product. It is an area of the product that can vary so much based on a large number of factors, and now that the product is released and in the hands of an exponentially larger pool of users, it is only natural that we are going to find more of these scenarios that require further fine-tuning going forward.
I would just like to note, however, that slow throttle response and some throttle hunting are traits of the real aircraft. The following video is a good example of some throttle hunting during the approach phase: https://youtu.be/aqao0PWyLug
The slow throttle response in the real aircraft is also part of the reason why the landing gear takes 32 seconds to extend. We have cockpit videos from the real aircraft that show pilots controlling the throttles during the approach, even with ATS engaged, as it can sometimes not respond quickly enough. That's something that is very tricky to simulate in home flight simulators, as most users don't have servo-operated throttles that move with the throttle position in the simulator.
In terms of logging feedback, the very best thing that anyone could do is to collate all of your feedback and send it in a ticket to Just Flight Support via the following link: https://www.justflight.com/support
The F70 & F100 Professional are complex simulations, so in order to give our support team the best chance at offering speedy assistance, and to ensure that all feedback gets logged correctly, we would kindly ask that any screenshots/videos of the behaviour are also included with your ticket, as well as attaching the log file generated by the product.
Instructions for locating the log file can be found here: https://support.justflight.com/en/support/solutions/articles/17000152594-where-to-find-the-log-file-s-
Mark - Just Flight
-
CRZ LVL out of range was also something I've noticed, also still not knowing if that's a feature or bug, but I couldn't insert any Cruise Level below FL100.
I've tried to insert as FL080, 080, 8000, none worked.Discovered that while short hopping and flying IFR paterns to practice this new airplane.
Found the answers for that under the manuals
"The minimum accepted flight level is 10,000 ft." -
Thank you for your feedback. Tuning of various AFCAS and ATS modes is something that we anticipate will be a continual ongoing effort throughout the lifespan of the product. It is an area of the product that can vary so much based on a large number of factors, and now that the product is released and in the hands of an exponentially larger pool of users, it is only natural that we are going to find more of these scenarios that require further fine-tuning going forward.
I would just like to note, however, that slow throttle response and some throttle hunting are traits of the real aircraft. The following video is a good example of some throttle hunting during the approach phase: https://youtu.be/aqao0PWyLug
The slow throttle response in the real aircraft is also part of the reason why the landing gear takes 32 seconds to extend. We have cockpit videos from the real aircraft that show pilots controlling the throttles during the approach, even with ATS engaged, as it can sometimes not respond quickly enough. That's something that is very tricky to simulate in home flight simulators, as most users don't have servo-operated throttles that move with the throttle position in the simulator.
In terms of logging feedback, the very best thing that anyone could do is to collate all of your feedback and send it in a ticket to Just Flight Support via the following link: https://www.justflight.com/support
The F70 & F100 Professional are complex simulations, so in order to give our support team the best chance at offering speedy assistance, and to ensure that all feedback gets logged correctly, we would kindly ask that any screenshots/videos of the behaviour are also included with your ticket, as well as attaching the log file generated by the product.
Instructions for locating the log file can be found here: https://support.justflight.com/en/support/solutions/articles/17000152594-where-to-find-the-log-file-s-
Mark - Just Flight
Dear Mark,
Thank you for getting back to me and for sharing the reference video.
However, I would like to point out a few things regarding the video provided. Since it was recorded from the passenger cabin, it lacks the flight deck parameters (such as EPR, IAS trend, and wind vectors) necessary to make a direct and accurate comparison between the real aircraft's ATS behavior and the simulator.
Furthermore, the meteorological conditions in the video clearly show active weather, with nearby CBs and apparent turbulence. In an environment with shifting wind direction and speed, it is completely normal and expected for the ATS to make significant and continuous thrust adjustments to maintain the target speed.
This contrasts directly with the video I recorded and sent to you. In my simulator footage, you can see that the wind direction and speed are completely constant. While perfectly steady winds are too unreal, in this controlled environment, a stable wind vector should not trigger such erratic ATS responses and severe thrust hunting. Without external atmospheric disturbances, the system should be able to stabilize the power setting rather than continuously chasing the speed.
I'll sent a ticket as instructed!
Thank you again for your time and assistance.
