This is some good info about MSA that I did not realize. But I am
still a bit confused. The AIM says that MSA provides 1000 ft clearance
over all obstacles, implying that it satisfies the minimum IFR
altitudes (in non-mountainous areas). Is this statement incorrect?
Also, if the MSA is not accurate for IFR, how much extra work is it
anyway to produce a chart with an MSA that conforms to IFR standards?
The numbers are already available from the enroute charts, so it can't
be that difficult, right?



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and are not assessed with the precision that are accorded IFR altitudes.

I'm not sure what you mean by "precision" here. The parameters are clearly
specified: 1000' above any obstacle in the designated sector. (The MSA
doesn't assure navaid reception, though, so that has to be assessed
separately.)

The folks who design approach procedures at the FAA use very precise
topographical information to design the published segments of an instrument
approach procedure. For MSAs, though, they simply use sectionals, which may not
provide the required obstacle clearance at all times, simply because sectionals
do not have the accuracy that USGS 1:24,000 topos have.

Plus, when the FAA assesses the published segments they add 200 feet of assumed
adverse obstacle ("AAO") pad, because folks can construct towers, etc, up to 200
feet high without notifying the FAA, unless the towers are within certain
distances of an airport. There is no AAO assessment made for MSAs, though.
Also, spot elevations on sectionals can be off by a fair abount, without
adversly affecting their stated purpose; i.e., VFR navigation charts. And,
contours on sectionals are very coarse, although that isn't usually an issue in
non-mountainous areas.