Hunting the (Sub) Hunters, Part II

Let's kick the tires and light the fires, big daddy

While you’re all probably thinking “Good Lord, another ships and planes article? Where does this guy get off?”, I am here to tell you…yes, this is another ships and planes article. I’m sorry? Anyway, my article from April about the navy’s submarine hunters got good enough reception that a very considerate and well-informed tipster reached out with even more data for me to explore. And if ships and planes aren’t your thing, then stay tuned for July’s first post, which will be a more technical, remote sensing-heavy tutorial.

Before getting into today’s article, I recommend checking out Part I, linked here, about the P-8A Poseidon anti-submarine aircraft of the US Navy’s Air Test and Evaluation Squadron One, aka AIRTEVRON ONE or VX-1 (which is how I’ll refer to them). I don’t want to rehash the whole thing here, but the gist is that the US Navy has a squadron of (at least) four P-8As responsible for finding new ways to hunt submarines. Using open sources like Facebook and flight tracking websites, I pulled some data about these planes and used the data to make educated guesses about what these planes were doing on certain flights.

But my dataset was relatively limited - it covered the month of March 2021 and comprised about 6,800 lines and 61,000 total data points. The new data set is exponentially larger. It contains 53,000 lines and over 1.8 million individual data points about the four aircraft. It also covers a longer time span, from January 8 to April 13, 2021.

With this colossal dataset comes new insights about the navy’s sub hunters. To keep things somewhat logical, I’ll split the piece into two parts - the first focusing on the insights gleaned from the data set as a whole and the second exploring some case studies and tying in additional open source information about these flights.

By the way, this is a Kepler map of all public locations of VX-1’s P-8s from January to April…looks like they had a busy winter.

The Metadata

The first thing I noticed about the full dataset is the difference between what I’m calling the P-8As’ “operational” and “travel” altitudes. The full dataset shows that when the Poseidons were on exercises or operations off the coast of the US, their altitudes were far lower than when they were just flying between two bases. A Navy pilot or actual expert would probably have more information about this than I do, but I, as a relative layman, thought it was fascinating.

The top map shows VX-1’s flights between roughly 29,000 feet and 41,000 feet, while the bottom map shows flights between about 10,000 feet and 29,000 feet. Notice the numerous (relatively) low altitude orbits off the West Coast, as well as the trails leading to and returning from the Atlantic.

I also colored the flight paths by ICAO24 number (a unique identifier for each airframe). Even though these planes are nominally based at Naval Air Station Patuxent River in Maryland, their range spans the country. Additionally, in this map, distinct narratives emerge for each airframe in VX-1.

The blue flight paths represent the P-8A ae222d, which, with over half a dozen patrols off the coast of California, is clearly a West Coast aircraft. It did have a few missions in the Atlantic, but not nearly as many as, say, ae2230, which appears to be the workhorse of the unit.

While ae222d mainly conducted maritime patrols, ae2230, in purple, appears to undertake both maritime patrols (primarily into the Atlantic) and routine flight training, such as takeoffs, landings, and touch-and-gos at bases around the country. It flew on at least half of the days covered in the dataset.

Unlike the first two aircraft, the remaining two P-8As, ae5f37 and ae4eb1, were relatively little-used. Ae5f37 (in yellow above) only had a single flight during the first four months of the year - a lengthy patrol into the northern Pacific from Naval Air Station Whidbey Island. Ae4eb1 (in red) had a few more flights, but not by much. Her flights, by contrast, were located on the East Coast.

The flight map allows us to examine interesting operating areas for the P-8As. I compared the flight tracks against an online ArcGIS map showing, among other things, military airspace regions and submarine lanes. Unfortunately, I wasn’t able to find shapefiles for these locations, so I couldn’t layer the flight paths over the areas in the ArcGIS map. Nonetheless, a left-and-right comparison between the two maps is still helpful.

One of the most interesting areas is where ae222d (in blue, above) took a few flights off the coast of Jacksonville, Florida. Comparing these flight areas with the maps shows that the flights were not only within the Jacksonville Operating Area Submarine Operating Area (succinct, I know), but also directly over a Military Submarine Transit Lane and the “JAX Ship Shock Box”, where explosives are detonated near naval vessels to test their resistance to, well, shocks.

Was the P-8A doing a bit of sub-hunting training? Or on its way to drop the hurt near a ship during a shock test? Either option is plausible, although I’m more inclined to believe the former, as the USGS didn’t detect any seismic activity in that area between January and April. (as an aside, the shock box explosions are often big enough to be detected by the USGS’s earthquake sensors).

On the right, the submarine transit lanes are in yellow, the ship shock box is green, and the Jacksonville operating area is in black.

Back on the West Coast, do you remember that single flight path in yellow by ae5f37 off the coast of Seattle? The ArcGIS map shows it took place squarely within the Pacific Northwest Operating Area - a stretch of sea used by the military to practice all sorts of sailing, flying, and firing activities. Even more interesting is that the P-8A is not only within that operating area, it’s also within a section of that area known as W-237, which extends south to roughly Aberdeen, Washington. According to the US Navy, W-237 is specifically used for anti-submarine training:

“W-237 is also a designated Anti-Submarine Warfare (ASW) range for coordinated ASW operations, sonobuoys, practice depth charges, and smoke markers”

While I suppose it’s possible that it was conducting routine training or testing equipment, it’s awfully interesting that the only flight between January and April for ae5f37 was in an anti-submarine warfare training range.

Well, I think that’s enough metadata1 for one sitting - let’s look at some pictures from space, shall we?

Satellites, Flight Tracking, ArcGIS, oh my

First up is a flight by ae222d off the coast of San Diego on March 15, 2021. While its flight pattern, over a military operating area and a Variable Depth Sonar Training Area is interesting enough, an examination of Sentinel-1 SAR2 satellite imagery yields even juicier results.

There were two naval vessels, which I believe were a Freedom-class littoral combat ship and an Arleigh Burke-class destroyer sailing near the P-8A’s flight pattern that day as well. There is also a visible interference band on the SAR imagery, indicating that either the destroyer’s AN/SPS-67 radar or the LCS’s TRS-3D radar were likely active when the image was taken. Whenever a C-band radar, such as those powerful military radars, is active in an area imaged by a Sentinel 1 SAR satellite, it creates a fuzzy band across the image where the ground radar’s waves interfere with the similar frequency radar waves used by the satellite to create a picture of the earth below.

Destroyers and littoral combat ships go together in sub-hunting like milk and cookies, with the LCS’s variable depth sonar and the destroyer’s towed and hull-mounted arrays all working in tandem. My guess is that the ships were on their way to or from an anti-submarine exercise in the training area, during which the P-8 provided an extra pair of eyes from about 24,000 feet above sea level.

Next up is my personal favorite - a flight by ae2230 off the coast of Virginia on February 9. The P-8A was tracked flying east off Virginia Beach before turning southeast, dropping altitude, and flying out of range. Three hours later, it appeared at a much lower altitude (less than 14,000 feet) flying northwest and returned to base.

Under the P-8A’s flight path were two naval vessels - a Ticonderoga-class cruiser and, for the first time that I’ve seen, a real, live, surfaced submarine. The cruiser was sailing northwest toward land, but the submarine, likely either a Los Angeles-class or a Virginia-class fast-attack submarine, was heading out to sea. It also shouldn’t surprise anyone that both the ships and the aircraft were within the Virginia Capes Operating Area.

The only problem is that, on the satellite imagery, the submarine and cruiser are relatively far away from where the P-8A ended up. However, accounting for the time difference between when the image was taken (around 16:00 UTC) and when the P-8A was out of range (between 21:00 and 23:00 UTC), shows that the submarine would have had more than enough time to sail to where the P-8 was flying.

(By the way, you’re probably thinking how the heck can you tell that little smudge is a submarine? Especially if, you know, part of it is underwater? Two reasons: 1. It’s black as night - most ships, especially those leaving Virginia Beach, are Navy grey (like the cruiser pictured nearby) or more brightly colored merchant ships. 2. Only submarines make that extremely distinctive triangle-shaped wake. They also have two parallel wake lines at the side of the sub joined by the rounded wave at the front. See here and here for more examples).

Anyway, a Los Angeles-class submarine can sail at about 23 miles per hour when surfaced. The Virginia-class can sail faster surfaced and both the Los Angeles- and Virginia-classes can sail faster submerged. But let’s assume the sub was sailing at 23 miles per hour when the image was taken at 16:00. That means it would have traveled about 115 miles by the time the P-8A went out of range and 161 miles by the time the P-8A appeared back in range. Either option would afford plenty of time for the submarine to get near to where the P-8A was. Those radii are charted below:

It’s entirely possible that the P-8A was trying to track, communicate with, conduct exercises with, or escort the sub spotted leaving Virginia earlier in the day. But, as with most open-source explorations, that’s only a guess based on me trying to connect the dots, so if you have other thoughts or guesses, don’t hesitate to let me know!

Given all we were able to figure out about these P-8As, it’s clear that the more robust dataset allowed for more and better insights into the sub-hunting experts of VX-1. I had a great time doing the data analysis, imagery review, and mapping for this project, so if you also liked it (or didn’t!) I’m always open to feedback on Twitter or you can email at lineofactualcontrol [at] protonmail [dot] com. And, as I said above, keep an eye out for the remote sensing exploration in a few weeks.



But as I said above, the data set is huge, so I had to leave a bunch of cool things on the cutting room floor. If you have questions, want me to dive into any other data, or pull out additional details from this set, just let me know!


All satellite images in this piece are credited to Sentinel Hub