One of the vital but
relatively unknown vessels of the Navy is the T-AGOS ocean surveillance
ships. The Navy operates a small fleet
of these vessels under the Military Sealift Command. This post offers a brief look at these
vessels and their function.
Function
As you might imagine,
getting detailed information on the functionality of these ships is
difficult. The vessels are broadly
tasked with surveillance of submarines.
Presumably this includes both tracking of submarines and development of
detailed acoustic profiles of submarine classes and specific submarines. Their primary “weapon” is the SURTASS
surveillance towed array sensor system which is intended to monitor submarines
at very long ranges.
Additional functions include
oceanographic and hydrographic data collection.
SURTASS
SURTASS is the mobile
version of the well known SOSUS system.
In its baseline configuration, the array was passive only but now
includes a vertical array active low frequency (LFA) source. This allows operation in a bistatic
mode. USS Impeccable began operating the LFA in 2004. Smaller versions of the LFA have been
developed for the Victorious class
vessels. Other versions of SURTASS are being developed for enhanced shallow
water submarine detection.
The horizontal array is 4900
ft long and is towed at a depth of 500-1500 ft.
Ships and Characteristics
The Navy currently operates
four T-AGOS ships of two classes. The
three-ship Victorious class was begun
in 1986 and the one-ship Impeccable
class was started in 1993. Additional
ships were planned in the Impeccable
class but were cancelled for budget reasons.
The ships are built with
SWATH (Small Waterplane Area Twin Hull) hulls for stability at low speed and in
heavy weather.
The current list of active
T-AGOS vessels is:
Victorious
T-AGOS-19
Able
T-AGOS-20
Effective
T-AGOS-21
Loyal
T-AGOS-22
Impeccable
T-AGOS-23
Here are a few physical
characteristics for the Victorious
class. The Impeccable class is similar, though larger.
Length: 234 – 281 ft
Displacement: 3400 – 5400 tons
Speed: 10 – 13 kts; 3 kts when towing
Crew: 20 mariners, 5 techs,
and up to 15 Navy crew
USS Impeccable |
Impeccable Incident
There is a demonstrable and
common sense need to provide protection for these ships when they operate near
unfriendly countries. Impeccable was invoved in a famous
incident of harassment by Chinese vessels in 2009 that illustrates the need for
protection. From a Naval War College report comes this summary of the incident (1).
“[Impeccable] … was engaged in lawful military
activities in China ’s claimed
EEZ. On 8 March 2009, five PRC vessels—a navy intelligence ship, a government
fisheries-patrol vessel, a state oceanographic patrol vessel, and two small
fishing trawlers—surrounded and harassed Impeccable approximately seventy-five
miles south of Hainan Island in the South China Sea. The fishing trawlers
maneuvered within twenty-five feet of Impeccable and then intentionally stopped
in front of it, forcing Impeccable to take emergency action to avoid a
collision. The U.S. government protested the PRC’s actions as reckless,
unprofessional, and unlawful. China responded that Impeccable’s presence in
China’s claimed EEZ had been in violation of Chinese domestic law and
international law. Impeccable returned to the area the next day under escort
of a guided-missile destroyer, the USS Chung-Hoon (DDG 93).”
Note that Impeccable did not have effective
protection during the incident. Failure
to provide protection is a recipe for disaster.
You’ll recall the Chinese forcedown and subsequent seizure and looting
of the EP-3 aircraft some years back.
Without ready protection, we run the risk of losing a valuable and
highly secret vessel.
LCS
The Navy continues to search
for a mission the LCS can be effective at.
Adapting a LCS to the T-AGOS mission would be a possibility. With at least a minimal level of
self-protection as well as some useful speed, the LCS-AGOS could operate with a
degree of defensive capability that the T-AGOS does not possess. Of course, the LCS is inherently
endurance-challenged but modifications ought to be possible to greatly increase
the range and endurance. This is not a
perfect option but might be a way to get more use out of an otherwise fairly
useless platform.
In summary, the T-AGOS
vessels provide a very valuable function in the Navy’s subsurface warfare
effort and, though less glamorous, deserve increased attention, upgrades, and
protection. All in all, an interesting
class of ship!
There are at least four cases where unescorted intelligence assets where attacked resulting in crew deaths or the surrender of the intelligence asset.
ReplyDeleteUSS Liberty
USS Pueblo
1969 EC-121 Shoot down
Hainan island incident
Quite right. Thanks. I was attempting to highlight only the incident involving this class of ship but the concept of protecting intelligence and surveillance units applies to all platforms.
Delete?? Given that many why don't we protect them? Seriously? Anti piracy work or 'presence' missions are more important?
DeleteIt's quite odd that our most secretive and valuable assets, flying/sailing near unfriendly areas receive no ready protection. There have been numerous reports of unsafe harassment of aircraft. We leave these assets hanging out on their own. Puzzling, especially after the various incidents over the years. It's not like it's a surprise when it happens, anymore.
DeleteSounds about perfect. Bit over kill.
ReplyDeleteOne wonders how long and LCS can sustain its full speed as the escort roll could be done at a distance along with a "patrol" roll ?
Otherwise its a hellishly expensive asset for the job.
Not a perfect fit for the LCS but I, and the Navy, continue to cast about for some useful role for the LCS. Still looking!
DeleteAside to Ben: Tomorrow.
This would be another job better done by the HI patrol frigate.
DeleteIn my town we have an old SURTASS ship. I've been on her. They are pretty nice actually.
Its the old T/AGOS Persistent.
Lucky you! I'd love to see one.
DeleteThey are pretty nice. All the TAS stuff has been pulled off as its a great lakes maritime academy ship now. One of the guys giving the tour was ex Navy. I did chuckle when I pointed out how nice the crew accomodations were. "Oh yeah. When I was on a 'Burke I had (X) inches. These kids have entire rooms..."
DeleteYou ignored its key advantage, diesel electric engines, which allow it to cruise slow and quiet to find subs. They have no weapons so they are not warships and cannot be attacked when they "accidentally" go off course several miles within the 12-mile limit while doing "ocean research".
ReplyDeleteBut .50 cals were mounted on the Pueblo just before she sailed, and her captain "followed orders" and refused to leave N. Korea waters for over a hour when confronted by NK boats, so it was boarded. All went according to plan, but the reason for this plan no one knows for sure.
I wonder if they are set up to run silently like the Spruances.
ReplyDeleteThey do reportedly have quieting features though I've never heard any details.
Delete