A new concept, the "Interim Forward Area Air Defense" (IFAAD) evolved around the Sidewinder. The main concern was that at shorter distances the missile would not have time to lock onto the target before it flew out of range, so to serve this need a second vehicle based around the M61 Vulcan cannon was specified. Both would be aimed manually, eliminating the delay needed for a fire control system to develop a "solution". Neither vehicle concept had room for a search radar, so a separate radar system using datalink was developed for this role.