Delta Air Lines, Air France-KLM and Virgin Atlantic have launched their combined joint venture, the carriers announced this week. The JV, first announced in 2017, enables flights across all four carriers to be booked through their respective channels and via agents. The carriers will begin "enhanced customer benefits" via their loyalty programs on Feb. 13, with reciprocal mileage earning and redemption and elite benefits across all programs. The four carriers combined represent about 23 percent of transatlantic passenger and cargo capacity, and the combined annual revenues of JV will be about $13 billion, according to Delta.