The Sikorsky S-72 Rotor Systems Research Aircraft (RSRA) was funded by NASA and the US Army to test advanced helicopter rotors in flight and featured detachable wings. Two S-72s were built and first flown in Stratford, CT on Oct 12, 1976. The first aircraft was delivered in July 1977 to NASA Wallops Island Flight Test Facility, VA and made its first full compound flighton April 10, 1978. The second S-72 was delivered to the NASA Ames Research Center in Fall 1978 and late joined by aircraft No. 1 in Sep 1979. Later used for RSRA/X-wing program 1986-1987. Msn 72-002 was NASA 546, 741 and N741NA.

This 2006 Airbus EC145 (BK 117C-2) N145SU of Stanford Life Flight is based on the roof of the Stanford Medical Center in Palo Alto, CA. It is one of three EC145s operated by Air Methods in California (i.e. Fresno and Children's Health of Orange County). Stanford's first helicopter was an Alouette III, N607RM, operated by Rocky Mountain Helicopters in May-August 1984, followed by a TwinStar N57898 (Aug 1984 to Sep 1986), a BK 117 (1986-2007) and a EC145 (2007-present). N145SU will be replace in Spring 2024 by a new Airbus H145 (117D-3) N1984S, msn 21114. Seen departing after refuelling at PAO.