Widebody; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Confusion; Human-Machine Interface; Situational Awareness; Workload
Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude
Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance; Flight Crew Took Evasive Action
Human Factors
Level at 6000 ft on the JIIMS2 RNAV Arrival DASHA Transition; between JIIMS and WOJIK fixes. Received a TCAS RA to descend; no sooner than I started the descent the RA command immediately changed to a climb. We climbed to about 6400 ft before returning to our assigned altitude of 6000 ft. I briefly saw the traffic before focusing all my attention to following the TCAS commands. TCAS maneuver was performed per SOPs. ATC never said a word to us before; during; or after the event. It appeared they had a lot to say to the other aircraft though. Both aircraft were under ATC control with the same controller at the time of the incident. Other aircraft either changed altitude or turned the wrong direction creating a reduction in separation with us.As long as there are at least two aircraft in the air at the same time this type of event may occur again. Know and follow SOPs.
A heavy jet Captain on the PHL JIMMS 2 RNAV Arrival took evasive action to a momentarily TCAS RA DESCEND command followed by a CLIMB command. The climb from the other IFR traffic was to about 6400 ft before returning to 6000 ft.