I've been searching for information about how the ATFLIR system tracks targets. I didn't come up with any authorative sources, this stuff isn't exactly published on the web for everyone to learn, but I did run across two different F/A-18 simulation games with highly detailed manuals. I would not consider them to be good sources at all, but I'm not relying on them for technical details. What I found makes common sense. From what I've learned, there are four ways the ATFLIR can be "aimed." L&S Slave- This means it will follow whatever you're tracking with the radar. This is the vertical "L+S" on the right side of the screen. Boresight Slave- This means it points at the aircraft's boresight, straight ahead. This is the vertical "BST" seen on the right side of the screen. Inertial LOS- This means the FLIR aims at a certain point in 3D space and it continues to aim there no matter what the aircraft does. Autotrack- The FLIR attempts to track whatever object falls inside the tracking area. The tracking area is the two vertical lines in the center of the screen on the left and right of the UFO. The manual states that the tracking area will contract to fit whatever you're tracking. I believe, but cannot confirm for sure, that a box will surround L+S or BST if either one are being used, so I think the FLIR was probably in Autotrack mode. For L&S, Boresight and Autotrack, one of these video game manuals said that if the FLIR loses the target, it will revert to Inertial LOS mode. Common sense tells me this is probably true in the real world. If you're tracking something and lose it, you'd want the FLIR to keep pointing in the direction it was last seen. It makes sense to default to Inertial LOS if the target is lost. With that in mind, I'm going to try to explain what I think the FLIR is doing in these frames. The first one is the very first frame after the zoom from MFOV to NAR, right before the target "zooms away." 1 Notice that after the zoom, the target is not inside the autotrack box. 2- The Autotrack box has started to enlarge. I believe this indicates that the FLIR is going into Inertial LOS mode and will continue pointing at this particular point in space until something comes into the box, it locks on and the box shrinks to fit it. 3- The Autotrack box expands more as it enters Inertial LOS. Target has moved left a little as compared to the center of the artificial horizon. 4- Autotrack has detected a target and shrinks the box but this leaves the target well outside. Big miss. Target has moved left a little more. 5 Target is now starting to "zoom away" 6 Zooming faster now. Autotrack expands to go back into Inertial LOS. The box stays this size for the rest of the video, that's why I think it indicates Inertial LOS mode. I think this is the default box size. It's waiting for a target to enter the box, at which point it will shrink to fit the target. It does get larger just as the video cuts out. I theorize that's because they're switching modes to something else, which also stops recording video of the FLIR. So, what can we learn from this? I don't know. I've made some assumptions based on a video game manual, but it's common sense stuff. If I'm right, I believe it shows that the lock on the object was lost immediately after the MFOV to NAR switch and the object is moving left immediately too. The video starts with the FLIR pointed at 4 degrees right of the aircraft and ends at 8 degrees left. The object was always moving left throughout the whole video. If NAR is a 1.5 degree field of view, can the object's move to the left be attributed solely on the fact that the FLIR is no longer moving to the left to track it?