Controllers are supposed to report level busts and most do. After an 'bust' has happened then they fill in a CAA report form which goes to CAA SRG. A copy of the original report is also sent to the ATC Investigations & Incidents department at the appropriate ATC facility. At both London Terminal Control (West Drayton) and London Area Control (Swanwick) there are investigation offices which then collate all the ATC information (which can also include a radar replay file and RT transcript) and they then try contact the airline/crew to discuss the incident and get some feedback. In many instances, the report goes to the airline Ops department or Head of Flight Safety and then is passed onto the crew for their comments. When a reply has been received, or after a suitable period if none has been forthcoming, the conclusions are passed to SRG for their action, if they consider it appropriate. The whole chain is designed to find out why level busts occur and how to prevent them. If there is a pattern of busts, or continued problems with a particular airline, then one could expect SRG/UK Flight Ops to take some further action. If there where continued problem with pilots misinterpreting the WU S.I.D charts, then contact may be made with the map publishers to agree some alteration to their format. Problems like interruptions to crew briefings, just highlight the importance of not being disturbed and their ultimate consequences.