This will indeed be eligible for compensation due to ‘ramp rash’. Don’t be surprised BA push back (pun not intended) on it and claim it’s extraordinary. The cabin crew were able to stay as they have bunks to use and can extend their hours through in-flight rest. The Pilots are unable to do this because BA operates ORD as a 2 crew route and it therefore doesn’t have a great deal of tolerance for delays as it operates right on the fringes of what is doable in a realistic way with only 2 of us. As 2 crew we can’t extend hours by the use of in-flight rest in bunks, we’d need a third pilot.

As an aside, the US carriers on the route (AA/UA) have 3 pilots for this route.

The pilots would have been called out from home standby and would need to be able to get to the crew car park within 2 hours from the phone going. From there it takes about 15 - 20 mins to get to the crew report centre and about 20 mins or so to get to the aircraft, assuming there was one at that point.

BA could choose to operate this as a 3 pilot route, it chooses not to. Not sure if that had any effect on the delay.

Ultimately the damage caused in the turning around of the aircraft is common place and not extraordinary. Any further delay due to lack of aircraft and pilots running out of hours are directly within BA’s control.