Originally Posted by
1Aturnleft
They could do what Britannia did back in the day and assign the same flight number for each round-trip... followed by the designator A for outbound and B for inbound. I guess AA with the complexities of a multi hub operation could opt for the designator N/S/E/W depending on routing

most US airlines already do this (same flight number inbound and outbound) - and have been doing so for years now. I guess a move to 5 digit flight numbers really is a must!