Embraer ERJ 170 100 SE N856RW accident near Summit, Mississippi

Probable cause

the abrupt maneuver that was appropriately initiated to comply with the TCAS resolution advisory caused by the momentary projected loss of separation from converging traffic. Contributing to the accident was a passenger's decision to disregard the seatbelt sign.

NTSB analysis

The rapid climb and descent of FAST13 within 30 seconds exceeded the radar systems capability to accurately track and display the altitude changes. Accordingly, the air traffic controller providing services to TCF7530 and FAST13 did not observe FAST13 climb above the assigned altitude of FL280 nor did the controller receive a conflict alert from the radar system.

The reason for FAST 13's deviation from assigned altitude was not determined.

The TCAS onboard TCF7630 alerted as expected and the first officer appropriately initiated a climb in response to the RA. The seat belt sign was on prior to the TCAS alert because the flight attendants were preparing the cabin for landing. Shortly before the event, a passenger elected to go to the lavatory even though a flight attendant advised the passenger to return to his seat. The passenger was in the lavatory when the TCAS RA occurred resulting in him receiving a serious injury.

Text from the NTSB. Open the NTSB docket for DCA10LA083 for the full record.