I was thinking EA-6B Prowler because its vertical stabilizer and engines don't stick out as much as the Viking's, and it could jam the F-18's radar.
Underwood: [...] And then we started seeing what we call jam strobe lines, strobe lines are vertical lines that show up on your radar that are indications that you're being jammed.
[...]
Underwood: I did get jamming cues on my radar tape, and you can see cues of jamming on both your radar and your FLIR tape. You know like when Commander Fravor described on your FLIR tape, when you see like 99.9 range to target. That means you're being jammed.
(
Source)
Following up on Agent K's hypothesis that the object in the FLIR1 video is an EA-6B Prowler, it may be helpful to look at the Nimitz Event Summary. The summary lists four events occurring on November 14 2004, Events 3-6 (Events 1-2 are not publicly available, as far as I know). Fravor's encounter with the Tic Tac is summarized in Event 3. The summary for Event 5 is here:
The Combat Search and Rescue (CSAR) component of the event (upper page) seems to be a simulated rescue of a downed pilot in a combat situation involving aircraft and helicopters from the following squadrons (
Source 1,
Source 2,
Source 3):
- Fast Eagles: VFA-41 Black Aces (F/A-18F Super Hornets - based off of Nimitz)
- Ravens: VAQ-135 Black Ravens (EA-6B Prowlers - based off of Nimitz)
- Indians: HS-6 Indians (SH-60F Sea Hawks, HH-60H Seahawks - based off of Nimitz)
- Camelots: VFA-14 Tophatters (F/A-18E Super Hornets - based out of Lemoore NAS Califonia)
- Banger: VAW-117 (E2C Hawkeye - NAS Point Mugu California, first deployment with Nimitz in April 2005 as part of OIF.)
The summary describes EA-6B Prowler(s) from the Black Ravens providing jamming for the simulated rescue operation while F/A-18Es (Camelot) performed rescue escort (RESCORT) at 12,000 feet, Seahawk helicopters (Indians) "remained with" the rescue escort, and F/A-18s (Fast Eagles) provided Rescue Mission Command (RMC). (Side note: I'm not sure what exactly "remained with" means in this context.)
In this kind of operation, one would suspect that the jamming would cover a wide area, since the intent is to confound enemy radar systems while the rescue/extraction occurs:
Source:
Naval Aviation News March-April 1996 p.11. The entire article from pp. 8-13 ("Desert Rescue V") gives a nice background on CSARs.
The point is that the Event Summary describes a complex rescue simulation involving multiple aircraft and helicopters, some of which were providing jamming, likely over a wide area. If true, this would mean that successful jamming would make multiple aircraft and helicopters operating within the training area difficult to detect by radar, and result in either faint returns or no returns at all.
It's not clear from the Event Summary where or when Event 5 took place. Does anyone know what 5B1, 5E1, 5F1, 5A1, and 5A2 mean? The "5" refers to the event number, but the rest is unclear to me. It's also unclear to me whether Underwood would be operating in the same area, or even as part of Event 5. Does anyone know what his FASTEAGLE designation is? Answering these questions could help determine if Underwood captured one of the aircraft participating in this CSAR exercise on his FLIR. In particular, it might provide support (or refute) Agent K's Prowler hypothesis.
Since the exercise also involved Seahawk helicopters, it might make sense to also consider the possibility that Underwood's contact was a Seahawk that was only faintly visible on radar due to the wide-area jamming provided by the Prowlers. Here's what an SH-60 looks like:
If you squint, the landing gear looks like two appendages protruding from the bottom

I'll leave it to the Photoshop and FLIR imaging experts on Metabunk to try to figure out if a Seahawk could be the object in the FLIR1 video. The best that I can do with my meager skills is point to the following images and say they look vaguely helicopter-ish:
Image source: Kaen's
post. Some of the videos posted by igoddard (
link) may also be useful. Again, I'll leave it to others to consider the helicopter hypothesis if they think it has merit, I'm just throwing it out there. If it can be ruled out easily, then great, that counts as progress in my opinion. The main point that I wanted to make is just that the Event Summary, and in particular Event 5, may provide clues as to what was going on in the area when the FLIR1 video was recorded.