Date: 201311
Local time of day: 1201-1800
Location: EWR.Airport, NJ
Flight conditions: VMC
Light: Daylight
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class E N90
ATC / advisory: TRACON N90
Second aircraft: Small Transport; Low Wing; 2 Turboprop Eng
Aircraft component: Traffic Collision Avoidance System (TCAS)
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Human factors: Time Pressure; Distraction; Situational Awareness
Second reporter function: Pilot Not Flying; First Officer
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Conflict NMAC; Flight Deck / Cabin / Aircraft Event Illness / Injury
Detector: Automation Aircraft RA; Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Took Evasive Action; General Physical Injury / Incapacitation
Contributing factors: Airspace Structure; Aircraft; Environment - Non Weather Related; Procedure; Human Factors
Primary problem: Ambiguous

Narrative: We checked on with Newark approach on VHF 128.55 descending to 8;000 FT.  The Controller cleared us to 5;000 FT and directs GRITY.  We received a clearance to 3;000 FT.  Out of about 4;000 FT the Controller called traffic at one o'clock and 2;700 FT.  We did not see the traffic.  At about 3;200 FT and 4 miles southwest of GRITY we received a traffic alert.  As we were leveling off; between 3;100 FT and 3;000 FT we received a Resolution Advisory (RA) to descend.  The 'descend' alert quickly became a 'climb' alert.  We reversed direction and began to climb.  At this same time the Controller reported traffic at one o'clock and 1 mile.  We told the Controller that we were responding to an 'RA.'   The First Officer spotted the traffic right under us with only a few hundred feet clearance.  The First Officer said the aircraft appeared to be a twin turboprop. We returned to 3;000 FT.  The Approach Controller gave an approach clearance to fly heading 070; maintain 3;000 FT until established; cleared for the 4R approach.  We landed with no further incident.  While waiting between 4L and 4R the lead Flight Attendant called to report a crew member injury.  The First Officer notified operations.


Second narrative: For whatever reason; the RA initially indicated a DESCENT and then instantly changed to a CLIMB. Since the Captain was flying; he did not see the threat aircraft (a twin-engine; T-tail turbo-prop) which I estimate was passing beneath our right wing by about 300'. An abrupt climb was initiated to approximately 3;500' until we were clear of the aircraft. Had the RA not changed; I am relatively certain I would have needed to override the controls to start a climb. Again; the Captain could not see the other aircraft from his seat and most likely did not realize it was almost right beneath us at that time. Once we were clear of the conflict; the approach was continued without event.


Synopsis: A B737 on vectors for a EWR visual took evasive action in response to a TCAS descend command which then reversed to climb because the traffic was below and climbing. During the abrupt reversal a flight attendant was injured.