 The "F-14C" was a projected variant of this initial F-14B with advanced multi-mission avionics.Grumman also offered an interceptor version of the F-14B in response to the U.S. Air Force's Improved Manned Interceptor Program to replace the Convair F-106 Delta Dart as an Aerospace Defense Command interceptor in the 1970s.The F-14B program was terminated in April 1974.