The following is from page 17 of the February 2001 issue of IFR Magazine. For more background concerning this altimeter issue, see "I'd rather RAAS."

One night years ago at Cleveland Center, a Lifeguard pilot and a controller found themselves in a dilemma. The pilot shot an ILS, canceled, lost the airport, climbed, and requested another approach clearance.

However, the altimeter was now more than an hour old, and the FSS that provided the altimeter setting upon which the approach was predicated had recently begun part-time operations. They were closed for the night.

No Remote Alternate Altimeter Setting (RAAS) minima had been established. The controller, knowing that an approach is not authorized if the altimeter setting is not available, denied issuing a second approach clearance.

The pilot argued, then threatened to call Congress. The watch supe got on the mic and told the pilot that he would give him the phone number of the Congressional Cloak Room, but he was not getting an approach clearance that evening. At best the controller could've treated it as an emergency and said, "This approach is at your discretion."

Nevertheless, safety in aviation is built upon the concept of backup systems being immediately available. In the tower/tracon I have main, standby, and even battery operated radios. Our radar has two primary channels, two beacon channels, and even two Mode S channels.

And like many of you, when I fly, I carry a handheld GPS and a handheld transceiver, just in case. Backup systems make good sense.

About three years ago I began to notice that the RAAS minima were disappearing from many approach plates where AWOS/ASOS installations were being certified. But RAAS made good sense.

What happens if the AWOS/ASOS that you're depending upon, fails for some reason? Will you be in the same predicament as the Lifeguard pilot? Or will you obtain a clearance and shoot the approach anyway, adding your own improvised buffer? That's what concerns me.

In April 2000, at the second quarterly meeting of the Air Traffic Procedures Advisory Committee (ATPAC), I got an opportunity to present my concerns. I'd heard that the reasons for removal of the RAAS data had their origin from input by the Charting Forum (industry pros puzzling over chart design).

This elimination of RAAS was apparently an effort to reduce unnecessary data to make the charts more readable. Apparently I convinced ATPAC that this was a misguided effort, as I have been advised that the FAA will no longer remove RAAS data. However, I understand that they won't go back and add the RAAS data that has been removed unless requested by the proper authority.

So, the next time you're flying into an airport that is served by a stand-alone AWOS/ASOS, consider what your options may be if you need to descend through the clag and the local altimeter setting is not available, and no RAAS minima exists.

If you trust that AWOS/ASOS 100%, and think it'll never fail, do nothing. However, if you want the piece of mind that comes with knowing you can instantly switch over to RAAS minimums and complete your approach in a legal (and safer) manner, talk to the airport manager and have them officially request that RAAS minimums be restored.

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Tom Lusch is an instrument pilot, and was a Center controller for 11 years before switching to Port Columbus, Ohio tower/tracon.