A satellite navigation backup study commissioned by the JPDO has given eLoran “the highest overall preference rating...particularly in the U.S.” Not yet publicly released, the 180-page document was prepared by ITT’s advanced engineering and sciences division and assessed seven candidates against a series of essential requirements. The candidates include DME/DME/INS; GNSS/INS; eLoran; VOR; “hardened” GNSS; terrain mapping; and multilateration. Leading requirements were the ability to support RNP values of 2.0, 1.0 and 0.3, for en route, terminal and nonprecision approach respectively, plus technical readiness by 2015 to 2025 and complete independence from satnav. The ability of eLoran to continue beyond INS coasting limits following satnav loss was also noted. The report concluded, “eLoran scored significantly highest for the general aviation segment, and eLoran integration into GNSS/eLoran FMS systems for general aviation and certain air carrier segments appears to be a viable and capable solution.”