Value Upon Approval, page-112

Airline by Size

Total
•Tier 1 (>25M Passengers)	16
•Tier 2 (10 to 25M Passengers)	32
•Tier 3 ( 3 to 10M Passengers)	70
•Tier 4 (<3M Passengers)	914
•Tier 4c (<1M Passengers)
•Tier 4d - Small Airline (<500,000 Passengers)
•Tier 4e - Extra Small Airline (<250,000 Passengers)
•Tier 4f - XXS Airline (<100,000 Passengers)
Active Airlines	1032

Passenger Volumes

That’s the best I could find in terms of airlines and tiers without paying for the data. Not as forthcoming as you’d expect. So American, United, Southwest and Ryanair, who are all very much in our wheelhouse, and we’re a fingernail away from bobs conservative calculations. Delta obviously already onboard. Let’s not forget about the 32 tier 2’s, 70 tier 3’s and 914 tier 4’s. I’m sure the little guys wouldn’t mind putting a little extra $$ in the piggy bank.

https://www.statista.com/statistics/269617/top-10-airlines-worldwide-by-number-of-passengers/
https://www.t2rl.net/airline/