A-12 Avenger IIA 12 Avenger airplane model. The A 12 Avenger II was an American aircraft program from McDonnell Douglas and General Dynamics intended to be an all weather, stealth attack replacement for the A 6 Intruder in the United States Navy and Marines. The aircraft suffered numerous problems throughout its development, especially with the materials, and when the projected cost of each aircraft ballooned to an estimated US$165 million, the project was cancelled