Even without the injections it would be dangerous. Aircraft which require two or more aircrew is decided based on workload during takeoff and landing. Multiple aircrews are used to both prevent error and crashes. It's literally there primary safety loop for complex commercial aircraft. Workload and the resulting errors remains the number one cause of accusing accidents according to both the NTSB and the FAA. Anyone hoping for fewer cockpit aircrews is fighting to support more aviation crashes. They want to shutdown pubic air travel?