Which action is required when a data block mismatch is detected as MISM?

Which action is required when a data block mismatch is detected as MISM?

• A. Supervisory notification
• B. Immediate action by pilot
• C. Re-transmit data block
• D. Pilot verification

Answer: (A)

When a data block mismatch is detected, the situation is treated as a data integrity issue that must be handled at a supervisory level. Escalating to a supervisor ensures that the mismatch is verified, the appropriate corrective action is authorized, and the event is properly logged for safety and accountability. The supervisor can determine whether a reissue, a manual check, or other remedy is needed and coordinate any further steps with the flight crew or ground systems. This is why supervisory notification is the best choice: mismatches between sent and acknowledged data blocks aren’t something a pilot or a basic data-link procedure can resolve on their own. Immediate action by the pilot or a standalone re-transmission without supervisory direction could lead to confusion, duplicate messages, or unsafe outcomes. Pilot verification alone doesn’t address the underlying data integrity issue, whereas notifying a supervisor ensures proper escalation and safe resolution.

When a data block mismatch is detected, the situation is treated as a data integrity issue that must be handled at a supervisory level. Escalating to a supervisor ensures that the mismatch is verified, the appropriate corrective action is authorized, and the event is properly logged for safety and accountability. The supervisor can determine whether a reissue, a manual check, or other remedy is needed and coordinate any further steps with the flight crew or ground systems.

This is why supervisory notification is the best choice: mismatches between sent and acknowledged data blocks aren’t something a pilot or a basic data-link procedure can resolve on their own. Immediate action by the pilot or a standalone re-transmission without supervisory direction could lead to confusion, duplicate messages, or unsafe outcomes. Pilot verification alone doesn’t address the underlying data integrity issue, whereas notifying a supervisor ensures proper escalation and safe resolution.