EASA SIB 2014-15
Controller Pilot Data Link Communications (CPDLC) - Data Link : Instruction to turn a specified number of degrees left or right (UM 215)
Summary
EASA Safety Information Bulletin SIB No. 2014-15 addresses the Controller Pilot Data Link Communications (CPDLC) Uplink Message 215 (UM215), which instructs pilots to turn a specified number of degrees left or right. The bulletin highlights that some avionics display the turn instruction as a three-digit heading rather than a relative turn, leading to potential misinterpretation by flight crews. This issue affects all aircraft and Air Navigation Service Providers using CPDLC systems.
What Changed
EASA SIB No. 2014-15 introduces awareness of a discrepancy in how UM215 turn instructions are displayed on some avionics, which can cause pilots to misinterpret the command as an absolute heading rather than a relative turn. It informs stakeholders that some Air Navigation Service Providers have stopped using UM215 to avoid confusion. The bulletin does not mandate changes but provides guidance to mitigate the issue.
Why It Matters
This bulletin is important because misinterpretation of CPDLC turn instructions can lead to aircraft maneuvering differently than intended, potentially affecting flight safety and operational efficiency. Operators and Air Navigation Service Providers need to understand this to prevent unintended aircraft responses and ensure clear communication between controllers and pilots. Training and operational procedures must address this discrepancy to maintain safe CPDLC operations.
What To Do
Air Navigation Service Providers should consider the variability in avionics display of UM215 turn instructions and evaluate their use of this message accordingly. Operators should incorporate this information into flight crew training and operational procedures to ensure correct interpretation of CPDLC turn commands. No mandatory compliance deadline is specified, and the recommendations are advisory only.