Friday, May 07, 2010

ASOS and NWS

a reply to Peters question from a friend in the NWS
"a question comes from our EAA Chap650. Why has the NWS stopped issuing real time weather advisories?
At least that's the story we are getting here.
The tower at KBMG is telling our pilots that their new WX briefing updated 5 mins before each hour instead of the previous current WX is due to the NWS delivery to them.
Is there any light you can shed on this topic?"


Pete,

The NWS has not stopped real-time weather reports! It never has and it never will. The KBMG Tower likely has a video monitor in their cab called a VDU that shows real-time weather from ASOS. How or if they provide this information to pilots is their choice not the NWS's. Our tower, KAMA, chooses not to provide real-time weather. What I -- and likely you -- hear on ATIS is the ASOS generated METAR which is issued at h+55 in benign weather. I know however, that KAMA ATC uses the real-time VDU weather to brief landing and departing aircraft. The only thing I can think of that will prevent KBMG from offering real-time weather is a broken VDU. The NWS will replace a broken VDU in less than 24 hours so long if FAA politics don't get in the way. If KBMG no longer has a VDU, then the H+55 METAR is probably the only weather they get. If so, it's sad.

ASOS has a ground-to-air frequency that you can tune in for real-time weather from about 20 miles out. KBMG's freq. is 110.2 MHz. But once again, the FAA (not the NWS) chooses whether or not to use this feature at airports with ATC services. KAMA does not use it and my office has made every attempt to turn on the transmitter but the FAA says "no". I don't know the politics behind this decision.

Most ASOS units also have a telephone number that you can call for real-time reports. Yours is (812-825-8046).

Keep in mind that most ASOS units are FAA owned -- not NWS owned. The NWS usually maintains them though. Dissemination of ASOS information to the aviation community is in all regards an FAA decision.

Remember "real-time" is never real-time. ASOS does 1-5 minute time averages before it reports the weather element.