Could be something to do with the naughty airlines 1)filing cruise levels below FL200 2) not using the usual routings.(Both probably as a result of longer than usual delays brought about by LACC introduction). Example quoted is tfc from EGKK routing to CPT to then leave CAS to the southwest, when usual routing is via SAM (thus increasing complexity and reducing capacity further). Routing of some flights from EGLC also singled out for mention.