Briefing, authorising and time away
Beagle makes a fair point in his last sentence at 36 above. In the Herc world we were all effectively self-authorising if you looked at the things an authoriser is supposed to cover. Many of our departures from base were at 00 very little and there were never any grown ups in flight planning at that time. Each task had to be written up and then authorised when all the Auth could do was confirm that you had a constituted crew that was correctly qualified. At some later date (even), and not just later time, as the Captain you did the rest. In any case, sometimes the end of the task and, therefore, the final sortie could be days or even weeks later.
Originally, that was it and you amended the auth sheets on return to indicate what it was you had actually done in the event of a revised itinerary/routing. Then the fun detectors noticed and if your task changed you had to fill in a new auth sheet showing the new details and leave a signed copy with the handling agent even though it was all backed up with signals etc. For this all captains had to be signed up as self-authorising when away from base. I never did find out who if anybody actually saw these distantly off-loaded sheets of paper.
I well remember being somewhat bemused when first made a squadron training captain. In that job I could arrange my own aircraft (if available), arrange my own crew and then self-authorise to go and do whatever without telling anybody else. However, if it was a route task backed up by the full panoply of Group's tasking organisation I had to get authorised by a flight commander.
The rules were written for FJ squadron type flying and it took a lot of time and effort to get them even to reflect anything realistic for transport ops.