A Qatar Airways Airbus A330 enroute from Manila to Doha made an emergency landing at the Kuala Lumpur International Airport (KLIA) after one of its pilots died of a heart attack mid-air. All 250 passengers on board landed safely, thanks to the Co-Pilot.
Thus, for aircraft, the plane can still be piloted safely due to the presence of both pilot and co-pilot. In case there is an emergency involving the pilot, as in this case, the co-pilot will take over the control of the aircraft.
Until now, I have been wondering about the case of vehicle accidents. It might be possible that some of the accidents occurs due to the drivers having an emergency such as having a heart attack causing their vehicles to be out of control and ended up with fatal accident. In that case, the blame will usually be put on the driver for driving recklessly. It would be very difficult for the police officer to identify the root cause of such an accident (i.e. the heart attack). Thus, the only possible reason is to put the blame on the poor driver for reckless driving.