Which of the following is NOT a source for local altimeter settings?

Local altimeter settings are critical for pilots to ensure accurate altitude readings during flight operations. Among the listed options, AIRMETs serve a different purpose and do not provide local altimeter settings.

AIRMETs, or Airmen's Meteorological Information, are weather advisories intended for the safety of pilots, particularly regarding hazardous weather conditions such as turbulence, icing, and low visibility. They provide information about various meteorological phenomena but do not include information about altimeter settings, which are crucial for altitude accuracy.

In contrast, the other sources—AWOS (Automated Weather Observing System), METAR (Meteorological Aerodrome Report), and flight service stations—are directly involved in providing altimeter information among other weather data. AWOS offers current weather conditions, including altimeter settings, while METAR reports are standardized weather observations that include altimeter settings as part of the critical information available for pilots. Flight service stations also provide altimeter settings as part of their services to pilots, ensuring they have access to accurate data necessary for safe flight operations.

Thus, the correct answer is the option that does not provide local altimeter settings, which is AIRMET.