General aviation[edit]
Main article: TAWS § TAWS Types
TAWS equipment is not required by the U.S. FAA in piston-engined aircraft, but optional equipment categorized as TAWS Type C may be installed. Depending on the type of operation, TAWS is only required to be installed into turbine-powered aircraft with six or more passenger seats.
A smaller and less expensive version of EGPWS was developed by AlliedSignal (now merged with Honeywell) for general aviation and private aircraft.[21]