AIM Text
- Many airports throughout the National Airspace System are equipped with either ASOS or AWOS. At most airports with an operating control tower or human observer, the weather will be available to you in an Aviation Routine Weather Report (METAR) hourly or special observation format on the Automatic Terminal Information Service (ATIS) or directly transmitted from the controller/observer.
- At uncontrolled airports that are equipped with ASOS/AWOS with ground-to-air broadcast capability, the one-minute updated airport weather should be available to you within approximately 25 NM of the airport below 10,000 feet. The frequency for the weather broadcast will be published on sectional charts and in the Chart Supplement. Some part-time towered airports may also broadcast the automated weather on their ATIS frequency during the hours that the tower is closed.
- Controllers issue SVFR or IFR clearances based on pilot request, known traffic and reported weather, i.e., METAR/Nonroutine (Special) Aviation Weather Report (SPECI) observations, when they are available. Pilots have access to more current weather at uncontrolled ASOS/AWOS airports than do the controllers who may be located several miles away. Controllers will rely on the pilot to determine the current airport weather from the ASOS/AWOS. All aircraft arriving or departing an ASOS/AWOS equipped uncontrolled airport should monitor the airport weather frequency to ascertain the status of the airspace. Pilots in Class E airspace must be alert for changing weather conditions which may affect the status of the airspace from IFR/VFR. 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.
Source: FAA Aeronautical Information Manual · current edition · paragraph 4-3-27.
Research Notes
AIM 4-3-27 covers compulsory reporting points — the geographic points where aircraft must make position reports to ATC.
Compulsory reporting points: When NOT in radar contact, IFR aircraft must report at compulsory reporting points (depicted on enroute charts as solid triangles). Report includes: position, time over the point, altitude, ETA next point, name of next point, and any remarks (weather, etc.).
When NOT required: When in radar contact, ATC tracks the aircraft and the pilot doesn't need to make position reports unless ATC requests one.
The standard report format (5 elements):
- Aircraft identification
- Position (the reporting point name)
- Time over the point (Z time)
- Altitude
- Type of flight plan, ETA at next point, and next point
Non-compulsory reporting points: Open triangles on enroute charts. Report only when ATC specifically requests.
Mandatory reports regardless: Some events require a report whether in radar contact or not — unforecast weather, equipment malfunctions, leaving an assigned altitude, etc. See AIM 5-3-3.
Reference: § 91.183 (IFR radio comms and reports); AIM 5-3 (Enroute Procedures).