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ASOS (Automated Surface Observing System)
An automated weather observing system that continuously reports surface weather at many airports, including wind, visibility, sky condition, temperature, dew point, and altimeter setting. ASOS observations often feed METARs and may be available by frequency or telephone when ATIS is not.
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- ATIS (Automatic Terminal Information Service)A continuous broadcast of recorded aeronautical information at airports with control towers. ATIS provides current weather, active runways, NOTAMs, and other operational information, updated hourly or when conditions change significantly.
- Attitude IndicatorAlso known as the artificial horizon, this gyroscopic instrument displays the aircraft's pitch and bank attitude relative to the actual horizon. It is the primary instrument for maintaining aircraft control during instrument flight.
- AV1ATEA mnemonic for the inspections and checks that keep an aircraft airworthy: Annual, VOR check (IFR), 100-hour, Altimeter/static system (IFR), Transponder, and ELT. Student pilots use AV1ATE with ARROW to confirm both documents and inspection currency before flight.
- AWOS (Automated Weather Observing System)An automated airport weather system that broadcasts real-time observations such as wind, visibility, sky condition, temperature, dew point, and altimeter setting. AWOS is common at nontowered airports and is a primary weather source when ATIS is unavailable.