Thanks marcus, very helpful. I made a new version of my model with the "carefully picked times", using the corresponding average rate of turn and time of flight between them (taken from your data, #117) to retrieve the plane trajectory, and matching the refined camera angles you have. The small differences add up and change the lines of bearing a bit, but it does not change the conclusions.
Here are the new lines of bearing I get :
With interpolation (your data) :
Not exactly like yours, but close enough. The problem here for the distant object hypothesis is that beyond 25 Nm (x=-20), its positions at PT3 and PT4 start to diverge from its positions at PT1 and PT2. It's not as pronounced in your case but we see it's starting to happen too around x=-30. A jet cannot be at PT1 and 2 and jump suddenly at PT3 and 4.
Updated model using ths refined data is here :
https://www.geogebra.org/classic/p4zhvaaf
Without interpolation (my previous model) :
Here the main result is the same, with things getting worse even quicker. It mostly comes from different rate of turns, I have them a bit larger than yours (I have 1.5/2/2.3 for RoT1/2/3, you have 1.55/1.88/2.16). As soon as the blue line starts being above the others, that means Gimbal would have to make a sharp turn to catch up with the orange and pink line. And very quickly this makes for a long trajectory, i.e. unrealistic speed for a plane.
The only plausible trajectories are comprised between 5 Nm (or even lower ?) and 30 Nm. From my lines of bearing, I would say maximum, 10 Nm. From your lines of bearing, we could extend to 30 Nm, but that would mean a non-moving or very slow object (i.e. not a plane). No trajectory from our lines of bearing supports the plane hypothesis. If too far the trajectory becomes chaotic, if too close the slowdown of the object is not compatible with a plane.
Let me know what you think. Could you develop on this : "a steadily moving object is consistent with this provided the error bars for the azimuths are taken correctly into account" ? What trajectory do you have in mind that supports this statement ?