Dunno about UK CAA, but some regulators require the Chief Pilot (or his minions) to monitor and investigate each use of Captain's discretion. If it is over-done the operator must take remedial action. Like hiring more crews, or setting realistic schedules. Some rules put a cap on the number of flights where discretion is allowed.
Having been in the seat where I had to deal with these reports almost daily, it is such a pain in the arse to go through all the investigative process computerised SMS requires. It got to the stage where it was consuming too much time when it was obvious that it was just the company 'culture' to assume that discretion could always be used. I eventually gave written instruction to the crews that they were not to accept unrealistic schedules. It was usually a particular route or flight pattern that came up time and time again, very cleverly within the rule cap. The number of reports coming in occupied most of the SMS, to the detriment of other safety issues.
Management did not like me telling crews to refuse trips, and regrettably there were some pilots who continued to go beyond the limits because somehow they thought that this would enhance their career prospects, or they simply wanted to log flight time to move on to greener pastures.
Using discretion regularly to get home is an abuse of the intent. It is playing on the human tendency to prefer being in one's own bed to yet another night in a hotel. How many accidents have resulted from 'gethomeitis' and how many more from pilot fatigue?
Last edited by Mach E Avelli; 12th Dec 2012 at 00:12.