Aircraft on the NTSB record: Bombardier CL-600-1A11

the pilots' failure to ensure the airplane was loaded within weight and balance limits and their attempt to takeoff with the center of gravity well forward of the forward takeoff limit, which prevented the airplane from rotating at the intended rotation speed. Contributing to the accident were: 1) PJM's conduct of charter flights (using PJM pilots and airplanes) without proper Federal Aviation Administration (FAA) certification and its failure to ensure that all for-hire flights were conducted in accordance with 14 CFR Part 135 requirements; 2) Darby Aviation's failure to maintain operational control over 14 CFR Part 135 flights being conducted under its certificate by PJM, which resulted in an environment conducive to the development of systemic patterns of flight crew performance deficiencies like those observed in this accident; 3) the failure of the Birmingham, Alabama, FAA Flight Standards District Office to provide adequate surveillance and oversight of operations conducted under Darby's Part 135 certificate; and 4) the FAA's tacit approval of arrangements such as that between Darby and PJM.