EMBRAER ERJ 170 100 SESHUTTLE AMERICA CORP
Summit, MS, USA · 2010-08-09·N856RW
What happened
NTSB summary, verbatimThe 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.
Photographs
1the aircraft, and what the investigators foundProbable cause
the Board's determinationthe 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.
Occurrence sequence
3 stepsNTSB coding · CICTT taxonomy- 1 · Enroute-cruiseCollision avoidance alert
- 2 · Enroute-change of cruise levelAbrupt maneuverdefining event
- 3 · Enroute-change of cruise levelNear midair/TCAS alert/loss of separation
Findings
1 causal · 0 contributing- CAUSEAircraft › Aircraft oper/perf/capability › Performance/control parameters › Altitude — Not attained/maintained
Sequence of events
5 timed eventsfrom the FDR factual report · claude-fable-5-1 (in-session)- about 11:33 CDTcruisep.4Aircraft level at 29,000 ft for about 55 seconds before the alert
- about 11:34 CDTcruisep.4TCAS Combined Control = Climb Correction and TCAS Up Advisory = CLIMB, lasting about 11 seconds
- +1 secondevasive maneuverp.4Autopilot Engaged transitioned to Not Engaged and the control column began moving aft; one second later AP Selected went to Not Selected and the column peaked at about 8 degrees aft, then moved forward to about -2 degrees a second later
- evasive maneuverevasive maneuverp.4Pitch oscillated from about 2 degrees before the event to 7, then 3, then 5, leveling at about 4 degrees; vertical acceleration increased to about 2.4 g, dropped to 0.5 g, then 1.25 g before settling; aircraft climbed to 29,600 ft
- after the oscillationsevasive maneuverp.4TCAS Vertical Control indicated Increase for 6 seconds, ending with the other TCAS discretes
NTSB analysis
from the final reportThe 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.