I would suggest that the ULBs requirements are:
...
Collectively the industry has been working
for years to revise the ULB standard.
It's not as "easy" as just switching the frequency as there are many tradeoffs involved (power vs. range vs. frequency vs. rate of transmission vs. size vs. weight vs. cost vs. crash survivability, etc.)
SAE did a ton of analysis and in 2012 produced a new LF-ULB standard (AS6254), specifying 8.8 kHz for 30 days, with an assumed detection range of 5.8nm in normal conditions.
This standard has already been incorporated into FAA TSO C200, and accepted by ICAO in 2012 (Annex 6 Amendment 36) which mandates LF-ULB on all aircraft with MTOW > 27,000 kg starting from January, 2018.
ICAO mandate aside, in practice we will basically have two types of ULBs:
- Standard frequency 37.5 kHz ULB capable of operations for 90-days
- Low-frequency 8.8 kHz ULB capable of operations for 30-days
For shallow water recovery not far from shore (like this AirAsia crash), LF-ULB doesn't matter as much and 37.5 kHz will continue to be used for many years.
For deep sea recovery, aside from MH370 consider that in the past 20 years there have only been 6 airline accidents with wreckage submerged in 1000m depth or deeper. Of those,
100% of the FDRs and CVRs were successfully recovered using existing technology.
The FAA and EASA will likely require LF-ULB only for transoceanic flights (> 180nm from shore) starting in 2018 or 2019.