In 1956, the U.S. Army adopted a new, and relatively simple, designation system for its aviation assets. Aircraft were divided into three different types – 'A' for fixed-wing aircraft, 'H' for helicopters, or 'V' for V/STOL aircraft, and then were given a mission modifier, which, unlike the USAF system, came after the type code: 'C' for transports, 'O' for observation and reconnaissance aircraft, 'U' for utility types, and 'Z' for experimental aircraft. Aircraft types designated in this system were numbered sequentially.[9]