I was practicing instrument approaches the other day in VFR as part of my IR training and was unable to get the weather over coms from the non-towered intended airport nor the next non-towered airport of intended landing while airborne 15 NM from each. If I am receiving the Metar with the latest time stamp from FIS-B, am I allowed to use the altimeter setting as the local for the approach or is the only suitable alternative is to call the FSS for the local altimeter setting if the AWOS/ASOS is still operational and reporting? My rationale is what the FSS is recieving is also what is being reported to FIS-B as long as the time is considered current.
I know if no FAA regulation requiring you to use the latest “1-minute” weather from the AWOS/ASOS by VHF radio as opposed to the latest reported METAR data obtained via ADS-B, and what you get on ADS-B will not be older than what you get from FSS. That said, you can't get current weather for that airport, you have to use the alternate weather per the Remarks block and, if so stated, raise the MDA/vis requirement as noted. If you can't get the altimeter for either the destination airport or the specified alternative airport weather, you are not legal to fly the approach.