'Party line' information use studies and implications for ATC datalink communications

As part of the Federal Aviation Administration's National Airspace System modernization plan, digital datalink communications will be introduced as a means of air/ground information exchange. Care must be taken, however, to continue to provide pilots with the 'Party Line' Information (PLI) that pilots currently overhear on the shared voice frequencies. Several studies have examined the importance of PLI through surveys and simulator studies. Pilots have consistently rated PLI as 'Important', with several specific information elements identified as 'Critical'. However, PLI is not a reliable source of information during high workload conditions, and it is not always compelling enough for pilots to commit to a required action for safety. Therefore, several recommendations can be made for datalink communications.