AN/PRQ-7 CSEL . . .Leap Second Kills Functionality

Maybe you heard about it. At midnight (Zulu) on 1 Jul 15, the world added a “leap second” to synchronize time with the Earth’s slowing rotation.

Big deal, you say? It is if your unit has AN/PRQ-7 combat survival evader locater (CSEL) hand-held radios, NSN 5820-01-499-4473, in its inventory.

Turns out, CSELs don’t continuously track GPS signals. Instead, they get a GPS fix and then shut down to conserve power. So when the time rolled over to 1 Jul, that additional second placed a timing difference between CSEL radios and the UHF base station that continuously tracks GPS. Doesn’t seem like much, but it kept all CSELs from receiving the UHF base station’s “every 8 second CSEL mode message,” and effectively cut off UHFSATCOM communications.

While the CSELs will still be LPE (low probability of exploitation), TAC/TAG (terminal area communications/terminal area guidance), SARSAT (search and rescue satellite aided tracking), and AM voice functional, you’ll need to perform a built-in test (BIT) on the radio set adapter (RSA) and re-initialize to get UHFSATCOM capabilities back. The BIT test must be performed on the RSA prior to initializing the reference radio. If you don’t, the initialization will fail, you’ll lose over the horizon communications, and you won’t be able to enter the CSEL network.

Depending on how your CSEL is used, you’ll need to follow one of the following steps for your radio:

  1. Reference radios used after 1 Jul 15. Perform a BIT test of the radio on the RSA following the instructions in TM 11-5895-1629-13 (Para, Jun 08, or Para, Aug 13). The BIT test is only required once for each reference radio. This erases all GPS navigation data, including the previous leap second adjustment.

Next, perform a standard reference initialization on the RSA. Instructions are in TM 11-5895-1629-13 (Active: Para, Jun 08, or Para, Aug 13; Passive: Para, Jun 08, or Para, Aug 13). The RSA mission loading station is now ready for use. Any non-reference radios (target/issued) subsequently loaded on this station will operate normally.

  1. Non-reference (target/issued) radios mission-loaded before 1 Jul 15. These radios must be returned to an updated mission loading station (see step 1) and, at a minimum, receive a GPS time and data transfer following the instructions in TM 11-5895-1629-13 (Para, Jun 08, or Para 4.2.6, Aug 13). GPS keys and mission data can also be updated per TM 11-5895-1629-13 (Para, Jun 08, or Para, Aug 13). This will transfer the new leap second adjustment to the operational radio. Return the radios to field use.
  2. Non-reference (target/fielded) radios used without performing GPS time and data transfer. Perform a radio BIT on the RSA. Then perform a passive radio reference initialization and the radios are ready for field use.
  3. Non-reference (target/fielded) radios that are mission loaded and do not contain current GPS COMSEC keys (mission data only). Perform a radio BIT on the RSA. Then conduct a mission data upload following TM 11-5895-1629-13 (Para, Jun 08, or Para, Aug 13).

Place a battery in the radio and power it up. From the main menu screen, select Radio Status, then Check Link Quality. When the “Get GPS Time” screen appears, select “Get Time,” and press “Enter.” Allow the radio to get the current UTC time. The screen will proceed automatically from the Get Fix screen until complete, then revert back to the Link Quality screen. The current UTC time will be present across the top of the main menu screen. Once UTC time has been acquired, the radios are ready for field use.

  1. Fielded radios which are 2nd-level zeroized or stored without batteries attached (such as life raft-no battery). There is no need to update these radios since they do not have UHFSATCOM capability. Radios in extended mission mode (such as life raft-with battery) or standard mission mode should be handled following the instructions in the second half of Step 1. Also, make sure you select Standard or Extended under Mission Type (mission dictated) and then reload the mission data prior to use.

Once you’ve completed the procedure and have regained UHFSATCOM capabilities, make sure you report compliance through the Modification Management Information System (MMIS). MMIS requires login through LOGSA’s Logistics Information Warehouse (LIW):

The MMIS application is in the LIW App warehouse. Once in MMIS, select the Safety & Maintenance Messages Notification/Confirmation folder, click Message Confirmation to confirm receipt of this message, and then click Non-Compliant to confirm completion of the maintenance action.

Questions? Check out CECOM Maintenance Action Message 2015-08-002. You’ll find a copy in the MMIS application. Or contact Rick Brand, the CSEL FSE Support Team Lead, at:

Lieutenant Commander Gene Pennisi with Helicopter Combat Support Squadron 4 (HCS4), Naval Air Station Norfolk, Virginia, uses the new Combat Survivor Evader System (C-Cell) during a survivor extraction exercise in participation with DESERT RESCUE IX.  Desert Rescue is the premiere Search And Rescue (SAR) training exercise involving Navy, Army, Air Force and Marine personnel.  It is conducted at the ranges of Fallon Naval Air Station, Nevada.


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