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On 27 August 2025 the Russian Fighterbomber Telegram channel published a videoclip taken by the pilot of a Russian Su-27SM fighter over the Black Sea that day. The video showed a US Navy P-8A Poseidon maritime patrol aircraft (MPA), with the Bureau number (BuNo) 169554, with its Raytheon AN/APS-154 Advanced Airborne Sensor (AAS) in the extended position: the first time that this has been seen ‘publicly’.

The mission had been tracked by the ItaMilRadar website, which revealed that the aircraft had taken off from Naval Air Station (NAS) Sigonella at around 0900 CEST, crossing Greece and Bulgaria before refuelling over eastern Romania. The aircraft then crossed the Black Sea before patrolling off Sevastopol and the Russian naval base of Novorossiysk. The Poseidon returned to Sigonella at around 1730 CEST.

A still from the video taken by a Russian ‘Flanker’ pilot on 27 August 2025 over the Black Sea. This was the first time that the AN-APS-154 AAS had been publicly seen in its ‘deployed’ position. The aircraft is Bu No 169554, operating from NAS Sigonella on the island of Sicily. [‘FighterBomber’ Telegram channel]
This was the latest in a series of similar missions in which P-8As have patrolled the approaches to Novorossiysk, which has replaced Sevastopol as the primary base of Russia’s Black Sea Fleet as a result of Ukrainian missile and drone strikes.

Patrols by AAS-equipped P-8As had stopped in March this year, when the Trump administration decided to cease providing intelligence data to Ukraine. Two AAS-equipped P-8A aircraft (168996 and 169554) flew from NAS Sigonella to Portsmouth in the United States on 8 March 2025. They subsequently moved to new bases to start a new mission of surveilling the US Border.

P-8 reconnaissance flights in the Black Sea region have now resumed at a renewed tempo, however, highlighting a continuing US commitment to Western efforts to monitor Russian naval activities in the Black Sea and to protect the so-called ‘grain corridor’, which remains strategically vital for Ukrainian exports.

A pair of AAS-carrying P-8As seen on the ground at NAS Sigonella, Sicily, on 5 August 2025, undergoing maintenance on the flight line. One carries the ‘LA’ tailcode of Patrol Squadron Five (VP-5), which is currently deployed to the US 6th Fleet area of operations. The aircraft furthest from the camera is the P-8A featured in the ‘Flanker’ video. [US Navy/Mass Communication Specialist 2nd Class Sang Kim]
A US Navy P-8A Poseidon (BuNo 169336) carrying the AN/APS-154 AAS and wearing the LA tailcodes of VP-5, seen during what the caption described as “a routine mission over the US Central Command area of responsibility” on 31 May 2025. The aircraft was probably pictured over the Black Sea. [US Air Force/Senior Airman Keegan Putman]
P-3s, P-8s and pods

Advanced multi-function radar systems designed to provide high-resolution ground mapping, moving-target detection and tracking, in over-water, over-land and littoral environments, have been deployed on US Navy P-3 MPAs and more recently P-8s for some years.

The AN/APS-149 Littoral Surveillance Radar System (LSRS) used high-resolution synthetic aperture radar (SAR) and inverse synthetic aperture radar (ISAR) modes to provide high-resolution pictures and to identify moving targets.

LSRS (or a precursor) was first noted on a US Naval Research Laboratory NP-3B (152739) in 1978, perhaps in prototype form. Developed in the ‘black world’, it seems to have entered service on the P-3C in about 1997. Some 12 systems were acquired, with 16 P-3C BMUP aircraft modified to carry the LSRS as BMUP+ platforms. These were 161121, 161126, 161132, 161404, 161405, 161408, 161411, 161414, 161415, 161586, 161587, 161588, 161589, 161590, 161593, and 161596. Additionally, 158574, 160293, 161337 were also been seen with LSRS.

These aircraft were assigned to US Navy patrol squadrons VP-1, VP-4, VP-8, VP-10, VP-26, VP-40 and VP-46.

The final three P-3Cs equipped with LSRS often operated without visible Bu Nos or modexes, and even lacked NAVY titles, although it is understood that they are/were 158574, 160293 and 161337 and that they were flown by US Navy crews using navy call-signs. It was rumoured that the aircraft performed drug interdiction missions along the US-Mexican border and in the Gulf of Mexico.

The AN/APS-154 Advanced Airborne Sensor was derived from, and replaced, the AN/APS-149 Littoral Surveillance Radar System that was previously used on a handful of US Navy P-3C Orion MPAs. [Wikimedia]
They were latterly operated by the Bureau of Personnel Sea Duty Component Dallas (BUPERS SDC Dallas), having also been noted apparently operating with the Naval Air Systems Command-Flight Support Detachment at Dallas and with VP-46, which deployed to Al Udeid Air Base in Qatar in 2005. It is entirely possible that the aircraft merely wore VP-46 markings and was actually still with BUPERS SDC Dallas. The final P-3C deployment with the SLRS ended in late September 2019.

The US Navy awarded a multi-year contract for the development of the AN/APS-154 Advanced Airborne Sensor (AAS) for the P-8A to the Raytheon Company in July 2009. Development was accelerated by making reuse of LSRS hardware.

The new sensor, featuring a dual-sided active electronically scanned array (AESA), was designed to replace the capabilities of the LSRS, but with increased emphasis on non-traditional anti-submarine warfare (ASW) sensing. A modern submarine displaces a lot of water as it moves, generating a wake – especially when moving fast and relatively close to the surface. That wake is invisible to the human eye on the surface, merging with the normal pattern of the waves, but advanced sensors with very high resolution and advanced data processing can pick out the faint wake from wave patterns, effectively detecting a signal from the mass of background noise.

An AAS-equipped US Navy P-8A Poseidon (BuNo 169571) flies a routine mission over the US Central Command area of responsibility on 28 February 2025. The aircraft is carrying the AN/APS-154 AAS and wears the ‘LF’ tailcode associated with Patrol Squadron 16 (VP-16) ‘War Eagles’. [US Air Force/Staff Sgt Jackson Manske]
The first AAS-equipped P-8A made its maiden flight at NAS Patuxent River, Maryland, on 20 May 2015. Testing by Air Test and Evaluation Squadron (VX) 1 ‘Pioneers’ and later VX-20 ‘Force’ at NAS Patuxent River preceded deliveries to Love Field in Dallas for operational use.

The operator is again BUPERS SDC Dallas, which has detachments at NAS Patuxent River and NAS Point Mugu, California, and has been described as a critical category 1A Chief of Naval Operations (CAT 1A CNO) special project unit. The unit is also known as NAWC-23.

The P-8A Poseidon has significant modifications to carry AAS, including ‘pylons’ to attach the pod (the extendable Special Mission Pod Deployment Mechanism (SMPDM) cradle). This lowers the radar pod, preventing obstruction of the radar’s field of view by the P-8A’s underwing engines. There is also an aerodynamic modification below the fuselage, above the front end of the AAS, and two large strakes below the rear fuselage.

At least 16 P-8As have been modified to carry AAS. Whereas the LSRS P-3Cs were extremely anonymous, the AAS-equipped P-8As have been seen with tailcodes, Modexes and NAVY titles.

By August 2019 AAS-equipped P-8As 167951 and 167954 had been noted with VX-20, while 167952/952, 169007/007, 169010/010 and 169335/335 were serving with BUPERS SDC Dallas. 168996 was seen at Love Field in March 2018 and at Kadena as LA996 in July 2019, ostensibly operating with VP-5 ‘Mad Foxes’.

Since then 169325/325, 169336/LA336, 169341/341, 169554/LK554, 169567/567, 169568/568, 169571/LF571, 170014/014 and 170015/015 have all been spotted carrying AAS.

Multi-Mission Pod

The AN/APS-154 AAS pod should not be confused with the newer Multi-Mission Pod (MMP) developed by Boeing using internal funds from 2016. The MMP is designed to carry sensors that are not organic to the Poseidon and attaches to the existing attachment points developed for AAS, using the same power and cooling. The 20 ft (6 m)-long MMP is shorter than the AAS pod and is designed to accept a range of modular payloads, potentially offering larger apertures for a variety of multi-sensor, multi-spectral, multi-intelligence capabilities. This could include equipment used by export customer nations.

The MMP was first marketed at the 2021 Dubai Airshow and the US Navy awarded a contract for integration of the pod on the P-8A in September 2023.

The MMP began testing on the P-8A at NAS Patuxent River in July 2024, with certification expected by the end of that summer. The aircraft used was a former AAS testbed: 167951/951 of VX-20.

A U.S. Navy P-8 Poseidon, with the Naval Air Station Jacksonville, Florida, flies away from the boom of a KC-135 Stratotanker with the 914th Air Refueling Wing, New York, August 28, 2022 in the U.S. Indo-Pacific Command Area of Responsibility. The Poseidon is multi-mission maritime patrol aircraft, specializing in anti-submarine warfare; anti-surface warfare; intelligence, surveillance and reconnaissance and search and rescue. (U.S. Air Force photo by Staff Sgt. Tiffany A. Emery)

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