There will have been 3 pilots on board. One can always rest so that you don't get over the maximum time. 23 hours is still at the limit of what you can do with

There will have been 3 pilots on board. One can always rest so that you don't get over the maximum time. 23 hours is still at the limit of what you can do with 3 pilots. For passenger planes, you would've probably needed 4 pilots.