Illegal charter sometimes referred to as gray market charter or Part 134.5, are flights operated for compensation by an aircraft that is not on the certificate of an operator with an Air Operators Certificate (AOC). Illegal charter is often hidden via non-compliant dry leases. Compensation doesn't need to be monetary. Aircraft not on an operator's Part 135 certificate does not have to comply with the same maintenance, pilot safety, training, duty time, and medical requirements. From 2010 through 2019, Part 91 jet operations had 31 fatal accidents compared to 3 for Part 135. For turboprops, it was an 82-to-15 margin. In addition to liability issues, Part 135 flights have a significantly stronger safety record.