The Grumman AF Guardian is the first purpose-built anti-submarine warfare (ASW) carrier-based aircraft to enter service with the United States Navy. It consisted of two airframe variants, one for detection gear, the other for weapons. The Guardian remained in service until August 1955, when it was replaced by the twin-engined Grumman S-2 Tracker. The Guardian was the largest single-engine piston-powered carrier aircraft ever to see service.

The Grumman S-2 Tracker was the first purpose-built, single airframe anti-submarine warfare (ASW) aircraft to enter service with the United States Navy. Designed and initially built by Grumman, the Tracker was of conventional design — propeller-driven with twin radial engines, a high wing that could be folded for storage on aircraft carriers, and tricycle undercarriage. The type was exported to a number of navies around the world. Introduced in 1952, the Tracker and its E-1 Tracer derivative saw service in the U.S. Navy until the mid-1970s, and its C-1 Trader derivative until the mid-1980s, with a few aircraft remaining in service with other air arms into the 21st century. Argentina and Brazil are the last countries to still use the Tracker.