Hong Kong, March 21 -- Air China, China Southern Airlines (CSA) and China Eastern Airlines (CEA) are allowing passengers using their apps to browse and book flights operated by competitors, Yicai reports. Read More Passengers can freely book the best option for their needs without any additional fees, with payments settled at a later date. However, prices for the same flight vary across the platforms of the three carriers with the lowest fare usually displayed on the operator's own site. The three airlines began trialing the service last year on routes between their home cities of Beijing, Shanghai and Guangzhou, an insider told Yicai. The innovation offers more flight options to their VIP customers especially premium frequent travelers sen...