Agency Says Automated Sensors Can Fail Causing Inaccurate Readings

The FAA has published an Information for Operators (InFO) to provide information regarding the use of an RTMA when sensors on an automated weather system fail to report the surface temperature at an airport.

According to the InFO, automated weather observation systems provide surface weather reports at many airports in the United States. Systems such as the Automated Surface Observing System (ASOS) or Automated Weather Observing System (AWOS) have reliably provided surface temperature reports at airports for over 25 years. Occasionally the sensors on these automated systems have been known to fail. Many airports utilize human weather observers to either back-up or augment these systems. However, at airports without a human weather observer to back-up or augment an automated system, the lack of temperature reports due to failed sensors has led to delays, diversions and cancellations in air carrier operations.

In response to the issue of missing surface temperature reports due to failed sensors, the FAA solicited the assistance of the NWS in developing an alternative system for reporting surface temperature that operators, pilots, and aircraft dispatchers could easily use. The NWS responded by developing an RTMA surface temperature report that provides a simple hourly report of surface temperature at an airport, every hour, 24 hours a day. RTMA temperature reports are now available at approximately 540 Title 14 of the Code of Federal Regulations (14 CFR) Part 139 airports at which air carrier operations could be conducted. The airports with RTMAs are listed within areas depicted on the RTMA website. The areas are: Alaska (akrtma), Guam (gurtma), Hawaii (hirtma), Puerto Rico (prrtma) and the 48 Contiguous United States (rtma2p5). Operators may begin using these reports immediately. To ensure you access the most current RTMA, you may need to clear the cache memory on your computing device or refresh your browser (e.g. Windows, ctrl F5, Mac/Apple R or command R or Linux F5, etc.), when accessing RTMAs throughout a particular day.

Operators who use RTMAs are expected to develop and implement policies and procedures as soon as possible that ensure the pilot-in-command (PIC), and for part 121 domestic and flag operations, the aircraft dispatcher, have access to, or are otherwise provided with current RTMA surface temperature reports during the conduct of operations at any airport where temperature is not being reported by an automated weather system or human weather observer

The FAA says that Directors of Operations, Dispatch and Operational Control Managerial Staff should ensure that the appropriate operator, pilot and dispatch personnel are aware of, and have access to current RTMA surface temperature reports whenever temperature is not being reported by an ASOS, AWOS or human observer.

FMI: InFO