Anomalous Aerial Vehicle (AAV) is the designation applied in official United States Navy reporting to the unidentified objects observed by personnel of Carrier Strike Group 11 (CSG-11) during operations off the western coast of the United States and Mexico in November 2004. The term was used in the “Nimitz Carrier Strike Group (CSG-11) AAV Incident Report” to distinguish the contacts from known aircraft, and was subsequently adopted by the Advanced Aerospace Threat Identification Program (AATIP), whose stated mission was to collect and analyse information involving anomalous aerial vehicles, known in common usage as UFOs.1
During the week of operations, the USS Princeton (CG-59) detected multiple AAVs on several occasions in and around the vicinity of the carrier strike group,3 with contacts recorded three separate times during the week off the western coast of the United States and Mexico.4 The objects were observed by the Princeton’s AN/SPY-1 radar descending from above approximately 18,000 metres into the radar’s scan volume at high velocity.5 Because the AN/SPY-1 was configured for air intercept of conventional aircraft, it never obtained an accurate track and quickly discarded the contacts as false targets to reduce radar clutter.6 The Princeton initially reported the AAV target at approximately 4,600 to 6,100 metres above mean sea level; due to an intermittent radar return, velocity data was unavailable.7 A reporter later characterised the radar operators as observing the objects descending approximately 24,000 metres in less than a second.2
On 2004-11-14, after detecting an AAV again, the Princeton tasked airborne F/A-18 aircraft for investigation and took over control of the flight from the E-2 Hawkeye controller, vectoring them toward the contact and achieving visual acquisition approximately 1.6 kilometres from the object.9 Pilots and weapon system operators from Strike Fighter Squadron 41 (VFA-41) obtained both visual and sensor contact at approximately N31 20’ W117 10’, about 130 kilometres south of the US/Mexico border and 56 kilometres off the Baja Mexico coast.8 The intercept involved aircraft from Marine Fighter Attack Squadron 232 (VMFA-232) and VFA-41, operating under Carrier Air Wing 11 (CVW-11), with the Carrier Airborne Early Warning Squadron 117 (VAW-117) E-2 Hawkeye providing early coordination.35 During the intercept, situational awareness was also conveyed via sporadic Link-16 tracks from an off-board sensor assumed to be the Princeton’s AN/SPY-1 radar.9
David Fravor, commanding officer of VFA-41’s FastEagle flight, provided the principal visual description of the object. His first indication of the contact was a disturbance on the water below the AAV before he gained visual on the object itself.13 He described the disturbance as localised underneath the AAV, appearing as frothy waves and foam almost as though the water was boiling, not appearing as a trail or wake.14 Fravor described the object as an elongated egg or “Tic Tac” shape with a discernible midline horizontal axis, uniformly white across the entire body, and approximately 14 metres in length.10 His weapon system operator corroborated the white, smooth appearance, adding that it had no edges, no nacelles, no pylons, and no wings.11 Fravor compared its hover to that of an AV-8B Harrier, the aircraft capable of hovering via thrust vectoring.12 As he manoeuvred for a closer pass, the AAV appeared to realign its axis toward the F/A-18, and the water disturbance ceased simultaneously.15 The object then ascended quickly and pulled its lift vector on and aft of Fravor’s aircraft at supersonic speed.16 The Princeton subsequently reported the AAV had relocated to the flight’s training combat air patrol area at the southern end of the training zone and climbed to approximately 7,300 metres.17 Fravor’s lead aircraft carried no forward-looking infrared (FLIR) pod,18 and his attempt to achieve a lock using the Joint Helmet Mounted Cueing System was unsuccessful.19
Chad Underwood, flying a subsequent intercept mission, observed the AAV exclusively via his aircraft’s FLIR. He attempted multiple times to transition his AN/APG-73 radar to Single Target Track mode, but the radar could not take a lock; the sweep would build an initial aspect vector that never stabilised before dropping and reverting to normal search.20 Underwood observed no jamming cues during these attempts, describing the behaviour as if the radar could not receive sufficient information to create a single target track file.21 The FLIR showed the AAV appearing stationary, with the only apparent closure resulting from the aircraft’s own movement, before the object began moving out of the FLIR field of view.22 The F/A-18F radar could not obtain a lock on the AAV at speed, though the FLIR could track it while stationary or at slower speeds.23 The commanding officer of VMFA-232, vectored separately to the area, never made visual contact with the AAV itself but observed a water disturbance approximately 50 to 100 metres in diameter, close to round, which he likened to something rapidly submerging.25
The incident report’s key assessments concluded that the AAV was no known aircraft or air vehicle in the inventory of the United States Navy or any foreign nation,26 that it exhibited advanced aerodynamic performance with no visible control surfaces and no visible means to generate lift,27 and that it demonstrated advanced low observable characteristics at multiple radar bands, rendering US radar-based engagement capabilities ineffective.28 The report also assessed that the AAV possibly demonstrated the ability to cloak or become invisible to the human eye.29 Regarding a potential undersea component, the report noted that a qualified submarine officer aboard the USS Louisville (SSN-724), which was operating in the vicinity of the USS Nimitz (CVN-68) as part of the strike group, reported no unidentified sonar contacts at any time during operations.31 Based on the absence of sonar contacts, the report assessed it was highly unlikely the AAV operated below the ocean surface, while also raising the possibility that the water disturbance observed by pilots corresponded to a cloaked or invisible craft.32 Throughout the 2004 USS Nimitz Unidentified Aerial Phenomena (UAP) encounter, the AAV did not take any offensive action against the carrier strike group.33 All AAV activity was reported to Vice Admiral D. C. Curtis by the commanding officers of the Princeton and VFA-41.34 Carrier Strike Group 11 (CSG-11) confirmed it had no prior knowledge of live-fire events, weapons testing, or experimental aircraft operating in the area, and had never previously encountered anything resembling the AAV.35