What's the ROI on ads anyway? I feel like ads are just a way to funnel money between corps. People who are forced to see ads are really not even the point anymore. This is like corporations subsidizing other corporations. Don't even matter that you buy that item being shown to you.
Found a website saying Youtube adviews are $100-300 per 10k (ad views, not video views). That's 1-3¢ per view. If we assume an ad is 10seconds, then your time is worth 0.1-0.3¢ per second, or $3.60-10.80 per hour.
An A380 looks to be 380-615 seats. I'd imagine they're more often optimising for space, so let's say 550.
Long haul flight, 10% of people at any time using inflight stuff, 8 hours, 4 ads per hour = 5500.18*4 ads watched. 1760 ads. There will be a massive premium for planes, but surely only one order of magnitude more (e.g. 10x). That's equivalent to give or take 20k YouTube adviews which would be $200-600 per flight.
There are a lot of planes in the sky every single day though....
The thing is, it's only a ROI if any of those passengers converts to a buyer. The act of seeing an ad creates no value for the manufacturer unless they are converted to a buyer.
What you are describing is a market that has the consumer (ad watcher) almost completely removed from the conversion of capital. Being forced to watch an ad, in this case, only benefits the airline by their receiving ad revenue. The passengers are nearly supflourous.
ROI from adverts is always a shitshow though. If you come off a plane and see <brand name product> and buy it, is it because you just saw an advert for it, or were you always going to buy it. There is of course stats that may show number of impressions vs. total purchases trend, but its still just massive correlation that I imagine there is a bunch of people pulling spreadsheets together to justify their marketing spend. Anecdotally, I've heard of data teams working with marketing teams and just going "whelp, whatever you need to justify your job", etc.
Real ROI via direct sales though, that's somewhat measurable since you have a direct cost of acquisition (sales person salary, overheads, etc) vs revenue.