Saturday, May 26, 2012

LHA-6 - Aviation Assault Ship

While the LCS is soaking up most of the attention of naval observers, there is another ship currently being designed and built that also has the potential to be controversial.  The LHA-6 class is being built as a replacement for the LHA-1, Tarawa, class.  Three units were anticipated as of 2010 to replace the five unit Tarawa class.  This illustrates the ongoing, steady decline in fleet size.

LHA-6 - Note Absence of Well Deck

The LHA-6 is a unique design in that, unlike any other amphibious ship, it has no capability to conduct a waterborne assault since it lacks a well deck.  The ship is designed and intended purely for airborne assault and aviation operations.  Cargo and vehicle transport will be limited to sizes and weights that can be airlifted.  How this will impact the ship's overall contribution to  an Amphibious Ready Group (ARG) and Marine Expeditionary Unit (MEU) remains to be seen.

Troop carrying capacity is designed for 1600 Marines.

The aviation capability is designed to support a notional mix of fixed-wing and rotary-wing aircraft consisting of 12 MV-22s, 6 F-35B JSF, 4 CH-53Es, 7 AH-1s/UH-1s, and 2 embarked H-60 Search and Rescue (SAR) aircraft.  Alternatively, it can embark an attack wing of 20 F-35Bs and 2 embarked H-60 SAR aircraft (3).  The hangar bay was greatly expanded compared to the Tarawa with the medical spaces being reduced by two thirds to make room.

Construction started at Huntington Ingalls on the lead ship in 2008 and delivery is scheduled for 2013.  The first ominous sign for observers is that when construction began the design was only 65% complete.  The Navy has been down the path of concurrent design and construction with both the LCS and LPD-17 class and both have proven to be unmitigated disasters.  To say that the Navy is slow to learn would be an epic understatement.  In fact, a GAO report cites high levels of construction rework and resulting delays due to design issues (1).

“According to program officials, LHA 6 has experienced a significant number of physical interference issues during construction that have required modifications, including ripping out of completed work, and caused work to stop at times.”(2)
GAO cites the LHA-6 cost at $3.3B as of 2010 (1).

Another potentially significant issue is the flight deck construction and its ability to withstand the intense heat of the F-35 (JSF) and MV-22 engine downwash.  There are repeated warnings in reports that the deck may have to be redesigned and reworked but that won’t be known for sure until construction is complete and operational tests can be conducted.

The Ship Self-Defense System (SSDS) is another anticipated problem area.  The combat system includes the SSDS Mk 2, CIWS, SPS-48E long-range air search radar, SPQ-9B horizon search radar, Cooperative Engagement Capability (CEC), Rolling Airframe Missiles (RAMs), Evolved SeaSparrow Missiles (ESSMs), SLQ-32B(V)2 electronic warfare systems, and Nulka-equipped Mk 53 decoy system.  DOT&E states,

“… it is unlikely that LHA-6’s Ship Self-Defense System (SSDS) Mk 2-based combat system will meet the ship’s Probability of Raid Annihilation (PRA) requirement against anti-ship cruise missiles (ASCMs).”
To be fair, this is a known problem with the SSDS across multiple ship classes.

[Thanks to a sharp-eyed reader (sharper than me, for sure!) who caught a math error, the following section has been re-written a bit]

As with the LCS, the Navy did not produce a concept of operations prior to starting construction.  It remains to be seen how an amphibious ship without a well deck and only very limited cargo/vehicle transport capability will contribute to an amphibious assault.  Given that there is no well deck, it is instructive to examine the single “wave” troop transport capacity provided by the CH-53s and MV-22s.  Each CH-53 can carry 55 troops and each MV-22 can carry 24.  For the notional mix of 4 CH-53 and 12 MV-22, that translates to a single wave capacity of 508 troops out the 1600 embarked.  Thus, it would require 3+ waves to get all the troops ashore.  That seems like a fair transport capability but, lacking any heavy lift, has the potential to leave lightly armed troops in a somewhat vulverable position. Presumably, the heavy gear could be supplied from other ships although that violates the "eggs in one basket" philosophy if the heavy gear ship is sunk or otherwise unavailable when needed. 

The key to whether this ship is ultimately deemed successful will be the operating doctrine applied to it.  Will it be used as a light infantry transport, a light carrier, some combination, or something else, entirely?  The jury will be out on this one for a while, yet.

I wonder if the Navy views this ship as more of a light carrier (the alternate aviation mix of 20 F-35s) to supplement the carrier groups in scenarios involving somewhat limited conflict such as the recent Libyan operation.  Given that a current supercarrier air wing only contains about 42-44 combat aircraft, as discussed in a previous post, the LHA’s 20 F-35s would represent half of a supercarrier’s combat capability.  If this is what the Navy has in mind, the success of the concept will depend on the capability of the JSF which has more than its share of problems, at the moment.  That's a topic for another day, though.

(1)  GAO, Defense Acquisitions, Assessments of Selected Weapons Programs, March                   2012, GAO-12-400SP, p.105
(2)   GAO, p.106
(3)   DOT&E, 2011 Annual Report, p.143


  1. 4 x CH-53s and 12 x MV-22s translates to a single wave capacity of 508 troops - not 220.

    This means that all embarked troops can be put ashore in 3 1/5 waves - not 7 1/2.

    I do agree that lack of a well-deck in LHA-6 is huge oversight. There's lots of heavy gear that you just can't get ashore via -53.

  2. Oops! My bad. Thanks for the correction.

  3. Since the LSDs have most tactical vehicle lift capacity and LHAs have more troop spaces, it would seem to me that losing the wet well (an obsolescent WW2 design feature) is no big deal?

    The bigger issue is an overall lack of landing spots in an ARG which is not solved by put wet wells into every warship and MUST be addressed by another ship type. IF that means adding another ship to the formation so be it. MLP will NOT hack it, nor solve most of the issues its intended for and still cost upwards of one Billion at the end of four ship run which hopefully will NOT happen?

    Key is getting the CH-53K into service.

  4. leesea, you lost me a bit there. When you say a lack of landing spots are you referring to helo spots or something else? Would you expand on your thought a bit more?

  5. Why is considered an LHA instead of an LHD? The island structure is far different than that of an LHA Not to mention that the bow of the ship is also squared off like that of an LHD. On top of that how can this ship be considered amphibious because it does not contain a well deck. All of the other amphibs have well decks, LPD, LHA-5, LHD, LSD. How does this classify as an amphibious ship.