MSA's in the USA
 

I seem to remember when reading the monthly "Terminal Checklist" quiz(about Jeppesen charts) in Professional Pilot magazine a while back that a reason that the MSA altitudes in the U.S. are emergency only altitudes is because the FAA does not confirm on a regular basis that a 1,000' obstacle clearance actually still exists(also a potential lack of navigational signal reception and perhaps ATC communication problems and ability to remain in controlled airspace). Does anyone know of an internet reference about the obstacle clearance problem mentioned above? Thank You