Use of the 2000s for mainline flights started being published in January 2015 for flights starting 7 April 2015.
Originally Posted by
ORDnHKG
Not really, from what I can see for October, other than that 2000+ flight number, 200-999 still are 319, 320, PMUA 757 (which are all sUA), and 1000+ still are 737 (which are sCO)
Unless you are talking about starting next year perhaps ?
No, has already begun. Plenty of examples in this forum, like an sUA 772 operating UA 78 recently.