Navy releases timeline of mysterious 2019 ‘UAS Swarm’ involving warships off California


In a previous update on our investigation into a series of drone swarm incidents in 2019, The war zone posted an intriguing, but heavily redacted info slide. Curiously, before our appeal could be fully processed, we and other FOIA filers received fully unredacted versions of the same slide attached to separate requests. The unredacted version of the slide provides several new details, namely a timeline of interactions between the United States Navy’s Arleigh Burke-class destroyer USS Paul Hamilton and several objects designated as “UAS” or unmanned aerial systems. To our knowledge, this is the first publicly available document to use the term “swarm” in relation to the incident.

Additionally, the newly released material includes an infrared image of three of the objects. The quality is too low to show the identifying characteristics of the objects.

You can see the now unredacted timeline and information slide here:

US Navy

The USS Information Slide Paul Hamilton interactions with several unidentified aerial objects on July 17, 2019.

The incidents, which we now know continued through the second half of July, have been the subject of considerable interest since 2020, when documentary filmmaker Dave Beaty first brought them to light.

As for this new timeline, it shows that the incident began around 2:56 a.m. Zulu time, also known as Greenwich Mean Time., on July 17 or 7:56 p.m. local time on July 16. US Coast Guard Data separately indicates that the USS Paul Hamilton stopped broadcasting its position via the Automatic Identification System (AIS) about 10 minutes earlier at 7:47 p.m. local time. US Navy ships are not required to broadcast via AIS and sometimes disable their transponder to reduce their overall electronic signature in heightened security situations.

Although the deck logs do not indicate why the USS Paul Hamilton disabled its AIS, other vessels in similar circumstances that month noted that they had disabled AIS transponders specifically due to possible UAS activity. Additionally, the logs indicate that the event began just after the navigation lights were turned on.

At the start of the incident, the timeline indicates that a UAS was spotted at a distance of approximately one nautical mile. Twenty minutes later, the timeline shows that two UAS were seen and one fell in the water. At 8:26 p.m. local time, several UAS were spotted. The timeline also indicates that the bridge was able to see flashing red lights.

At 8:50 p.m. local time, the timeline shows a “UAS swarm.” At 9:11 p.m., the timeline indicates that one of the objects was directly overhead at 2,000 feet. Just a minute later, all of the objects appeared to change course and move away from the ship at 60 knots, or 69 miles per hour. However, eight minutes later, drones were again seen behind the vessel. The last event noted on the slide is when one of the UAS passed through the ship at approximately 2,000 feet. In total, the event appeared to last from 7:56 p.m. local time until 10:39 p.m., a total of two hours and 49 minutes.


USS Paul Hamilton going on at night.

Due to the very abbreviated notation in the information slide, it is difficult to discern exactly how many total contacts were spotted, or how many were observed over an extended period of time. The image embedded in the information slide, which was taken using an unspecified infrared (FLIR) system, is of extremely low resolution. Three fuzzy spots are discernible, but there are no other visible details.

Since the slide and image appear to be part of a larger presentation, we asked for the full document it came from. In response to this request, we were told that the USS Paul Hamilton and the offices of Commander Naval Surface Force Pacific and Strike Group Nine did a search and determined “no relevant documents exist”. We were also told that “the recording previously provided to you in a separate request was titled ‘UAP Brief’ by the Command FOIA Coordinator for his own use to distinguish it as a PowerPoint slide. It’s not part of a larger file. Although according to the Navy, this slide is not part of a larger presentation, we are aware that at least one classified briefing document was prepared regarding the incident pattern. This document consists of six pages, and its communication has been refused to us for reasons of national security.

The war zone

It is important to note that the unredacted version of the slide and photo was provided to us as part of a request for video footage or photos produced in relation to these incidents. Given the reference to possible videos in the map legend, we have sought clarification from the Navy FOIA coordinator responsible for this request as to whether the FLIR image was the only media that had been located in regards to this incident. As of this writing, the Navy says it is the only releasable photo or video he has of this event:

US Navy

The FLIR image of the USS Paul Hamilton from July 17, 2019

It is unclear which system produced the image, or whether local conditions may have impacted the clarity of the image. It should be noted that the region has seen a bit of fog at the time of this incident. Since the USS Paul Hamilton was some distance from any established weather observation station, it is impossible to know the exact local conditions. However, the fog may have played a role in the visual identification and photographing of the objects. However, the destroyer has several infrared sensors, including an extremely powerful one. Fog has varying levels of impact on infrared imaging equipment depending on the band it is designed to operate on.

The description of the flashing red lights matches the descriptions in the other logbooks. After attractive redactions, we recently obtained this USS log John Finn from the evening of July 14, in a separate swarming incident:

US Navy

USS John Finn deck log

The log contains a similar description of a possible UAS with flashing red lights crossing the vessel from port to starboard, this time at an estimated altitude of 1,000 feet. Full alignment with all other ships in the area proved difficult. Not all vessels submitted deck logbooks for the period concerned, in particular the Independence USS Littoral-class combat vessel Omaha. In the case of Littoral Combat Ships, digital records are also kept in a voyage management system (VMS). However, these VMS records have now passed the retention period. No explanation was given as to why the logs were never created.


Watchmen watch the action as the USS Paul Hamilton sails through the Strait of Hormuz.

Several characteristics emerge from this chronology. First, to our knowledge, this is the only publicly available Navy document that directly describes the event as a “UAS swarm.” As noted in other incidents of this general period, the overall duration of the event was quite long. However, it is unclear exactly how many contacts were detected and whether they were observed continuously, or whether it was possible that some of the objects arrived in waves. The timeline also notes at least one object falling into the water, making it possible that some of them lost power or malfunctioned during the incident.

The timeline makes no indication of the use of countermeasures, which we now know were exercised over the following weeks. Other records indicate that portable anti-drone devices were likely introduced to at least one ship plagued by drone sightings in the following weeks.

Strangely, the corresponding deck logs from this period show nothing out of the ordinary. The complete logbook recordings of the evening of July 16 from the USS Paul Hamilton are available below:

US Navy

US Navy

Cumulatively, these new records continue to paint a very concerning picture. The incident described in the information slide was one of several that occurred during the second half of July. Our previous coverage showed that the Navy’s investigation into this case did not appear to have had much success and posed similar unanswered questions about the intent of UAS operators.

Asked about these incidents during a press briefing in April 2021, the chief of naval operations, Admiral Michael Gilday, said the navy had still not determined what these planes were or who they belonged to. The Department of Defense and Navy declined to answer subsequent questions about it. As such, it remains unclear as to the exact extent of the security flaws or the effectiveness of the anti-UAS technology going live later this month.

In addition to being concerning, taken cumulatively, the documents are also puzzling. It remains unclear why the Navy released a heavily redacted version of the chronological document, only to release it again without any redactions. Also, it’s odd that an event described as a “UAS Swarm” results in a detailed timeline and presentation slide, but no obvious reference to events in the underlying bridge logs.


the Independence USS Littoral-class combat ship Omaha.

With respect to deck logs more generally, logs from other ships, such as the USS Omaha, are incomplete, apparently because they were never created in the first place. For such a major event that resulted in an investigation and briefing by the Chief of Naval Operations, the fact that deck logs were never even kept or retrieved from any of the ships involved is puzzling.

While the latest version provides a supposed picture of the objects, it is so unclear that it adds next to nothing to our understanding. It remains unclear to what extent the Navy itself understands these incidents, despite the seriousness of being repeatedly overrun by unknown aircraft near territorial waters. Given the vast array of sensors deployed aboard a fleet of their most advanced warships that have been involved in these events, there is likely an enormous amount of data that they are not releasing to the public and not not even comment anecdotally.

We will continue to investigate and keep readers informed of what we learn about these strange occurrences and the Navy’s response to them.

Contact the authors: [email protected] and [email protected]


Comments are closed.