The regulating rules of charter operators are almost similar to those of scheduled air carriers. The main difference is the size of the aircraft. Obtaining a charter operator's certificate can be a time-consuming process. It takes a minimum of three years of prior charter experience before a person can qualify to own a charter company. Every part and component on the aircraft must be documented to show they are within the Federal Aviation Administration’s (FAA) time limits before they can be certified for charter. Charter companies and pilots are certified by the Federal Aviation Administration (FAA) before they are allowed to fly. Their operations are, at the FAA's discretion and within its resources, subject to constant oversight under rigid safety regulations. FAA staff routinely audit charter operators' records, which can also be subject to a periodic safety review by independent safety auditors. Charter pilot qualifications are comparable to those for commercial airline pilots, including minimums for training and flight-time experience.