What is this annoying box under the seat of a 767?

Photo here.
There’s one of these on every row of seats (meaning that there’s one on the left 2, one on the middle 3, and one on the right 2). It looks like some sort of video distribution box, but there are no screens on the seatbacks. Even if it was, why is it so huge? It looks like it’s made with vacuum tube technology.

Also, as a bonus question, why are the seats lettered in such a strange fashion? I was in seat E and my wife was in seat C - next to me. There was no seat D.

I think it has something to do with the entertainment system. This is one of those planes that has personal screens for each seat, right?

For the seat letter, I’ve always assumed they could have different configurations. So if the side section could have three seats, but is configured to only have two, then you see it go from C to E, showing D has been removed.

There were no screens at each seat.
Video distribution for personal screens was my first thought, too. But, if that’s what this device is, and it’s just unused because this plane doesn’t have those screens, why don’t they get rid of it? One would think that ditching 150+ of this would save 1,000 pounds or more of dead weight - maybe they could afford to lower their damn luggage fee…

Looks like inflight entertainment gear. Which I see you say it isn’t. It might be the power supply for low-voltage cigarette lighter-style power ports for PCs & other personal electronic gizmos.

Those seats are a pretty old fashioned design, maybe 15 years old. If, as you say, the seat backs don’t have video screens, then those housings may well have been empty, with the heavy electronics innards removed to save weight.

For low power consumption, those kinds of components usually don’t have cooling fans. Which leads to oversized boxes with lots of vents & not much inside them.

“FAA Certified” and “consumer electronics” are ideas about as far apart as humanly possible. Like fine Soviet Diesel powered toaster. Comrade toaster warm you!

That’s where they keep the snakes, of course.

Sounds plausible. What airline was this, beowulff? Even though there were no individial screens, did the seats have any kind of local audio connection plugs in the armrests, be they active or inactive? Because one thing that can happen is that as carriers fold and merge you may end up with gear that is “legacy” from a different carrier or an earlier time in the carrier’s life when they DID provide entertainment or AirPhones.

As to the oddball seat designation, each airline tries to do some sort of pattern so that for instance, all "C"s are an aisle seat and so forth (heck, Continental tried to give all the exit seats in all their airplanes the same sets of row numbers, never mind how long each ship.). They may even change the pattern in each class cabin.

It was Hawaiian Air. There was audio output at each right armrest. Also, the box was “active,” because I reached down to the vent, and it was warm. I could see a coax cable running to each box (may be visible in the photo).

Then** LSLGuy’s** explanation sounds even better - gear for the audio system, in a large one-size-fits-all box.

I don’t remember such a large box on any of the flights that I’ve been on with in-flight audio systems. And while the ones that had seatback video screens did have boxes like that, the boxes were a lot smaller.

ENOUGH IS ENOUGH! I have had it with these…

Oh, never mind. 2006 wants its meme back.

Hawaiian Air has, apparently, 17 B767s with an average age of 15.5 years, which matches LSLGuy’s seat design age estimate. It’s unlikely the interior would have been overhauled, while airlines that do offer in-flight entertainment systems will have gutted and installed all new interiors and wiring. So these seats and the boxes are 15+ years old in design (hard to know how much older the interior design/approval is).

Or it could be the power supply for the treadmill.