An approved Remote Altimeter Setting Source (RASS) provides minima that used to always be published and immediately available for the pilot should the local altimeter setting not be available.

The following is a before and after comparison of the minimums section of a chart from Ohio University (UNI), . It is presented here for educational purposes only. NOT TO BE USED FOR NAVIGATION!

Before...

After...

Yes, the "clutter" is gone, but so is the important minima that the pilot could instantly switch to in the event that the local altimeter setting becomes unavailable, unreliable, (or questionable).

The Fall 1999 Air Traffic Bulletin gives clear guidance that "Approach minimums are authorized only for the approved altimeter source." Therefore, without the local altimeter setting, and assuming there is no NOTAM advising of amended minimums, the instrument approach procedure is NOT AUTHORIZED.

How long do you think the time period would be between when an AWOS or ASOS unexpectedly fails, and these amended approach minimums would be published in a notam?