Yesterday I was listening to LiveATC at McClellan Field (KMCC) since many CAL Fire Tankers are stationed there and there's a lot of activity recently.

As the tankers returned from their bombing runs, they called McClellan Tower and reported they had the "One Minute Weather".

Most seemed to be flying VFR if that matters, although the Tower was handing out Squawk codes to those that requested them (on departure, probably for better TCAS reporting, coordination and general awareness I presume).

I'm unfamiliar with the weather report "with one minute weather", what does it mean? Is it a quick way to report they have the latest ATIS information?

  • 2
    $\begingroup$ Squawk codes aren't just for IFR, almost every time I fly out of a controlled airport I'm given a squawk code. The only time you want to use 1200 (still a squawk code) is if you are in uncontrolled airspace, flying VFR, and don't want radar services. $\endgroup$
    – Ron Beyer
    Commented Oct 11, 2017 at 20:57

1 Answer 1


It's used at uncontrolled airports to tell approach controllers that you've got the AWOS/ASOS there. I believe the tower at KMCC is temporary (probably for firefighting).

The AIM 4-3-26 is snappily titled Operations at Uncontrolled Airports With Automated Surface Observing System (ASOS)/Automated Weather Sensor System(AWSS)/Automated Weather Observing System (AWOS), and says:

If ATC service is required for IFR/SVFR approach/departure or requested for VFR service, the pilot should advise the controller that he/she has received the one−minute weather and state his/her intentions.
EXAMPLE“I have the (airport) one−minute weather, request an ILS Runway 14 approach.”

It's also in the Pilot/Controller Glossary:

ONE-MINUTE WEATHER− The most recent one minute updated weather broadcast received by a pilot from an uncontrolled airport ASOS/AWSS/AWOS.

And this from the ATC Orders 5-10-2:

Automated weather observing systems may be set to provide one minute updates. This one minute data may be useful to the pilot for possible weather trends. Controllers provide service based solely on official weather, i.e., hourly and special observations


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