CPDLC UM148 Misinterpretation

The CPDLC Uplink Message 148, or UM148 is a widely used CPDLC uplink message in both FANS and ATN environments. UM148 uses the message element, “WHEN CAN YOU ACCEPT” when a controller needs to know the earliest time at which an aircraft can accept a specified altitude or flight level. Recent reports indicate that this message is sometimes misinterpreted by flight crews as a clearance to climb or descend. This quick topic video will demonstrate how to properly respond to a UM148.