<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by Markonen:
BA has a (totally undocumented) ticketing deadline of approx. three weeks for tickets that they consider to be "high risk". So, regardless of there being no advance purchase restrictions on a fare rule, BA can and will cancel a reservation if the ticket numbers are not on the PNR within three weeks of reservation.
I actually wish that this rule existed for other airlines as well. 'A' inventory is scarce enough without imaginary bookings.</font>
Actually most airlines do. Especially on CX, SQ and other asian carries. North American carriers only implement this on their special fares and not usually their First Class fares.