Loran E endorsed
 

If the world switches to ADS-B as a surveillance base, there will certainly have to be a positon backup souce in case of GPS failure or a compromise of its signal. Looks like E-Loran may get the nod.

JPDO Study Endorses eLoran as Best Satnav Backup
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."