Date: 201505
Local time of day: 1201-1800
Location: IAH.Airport, TX
Flight conditions: VMC
Light: Daylight
Aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class B IAH
ATC / advisory: Tower IAH
Second aircraft: Small Aircraft; High Wing; 1 Eng; Fixed Gear
Reporter organization: Air Carrier
Reporter function: Pilot Flying
Reporter qualification: Flight Crew Commercial
Human factors: Communication Breakdown; Workload; Situational Awareness; Distraction; Confusion
Anomaly: ATC Issue All Types; Conflict NMAC; Deviation - Speed All Types; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Aircraft RA; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Returned To Clearance; Flight Crew Took Evasive Action
Contributing factors: Company Policy; Human Factors; Procedure
Primary problem: Procedure

Narrative: Our initial clearance was PITZZ3 Departure; climb via the SID/4000.  While waiting for departure; short of the runway (15R); we heard tower reclear Aircraft (AC) departing both runways to climb to 2;000 for traffic southeast of the airport.  The transmissions from tower to an aircraft who's ID I can't remember seemed to indicate that it might have been a police aircraft as he was calling out roads; to indicate his current location and changes to his flight path.  When we were cleared onto the runway we were also recleared to 2;000.  The SID calls for a right turn to JAYLO out of 600 feet.  As we rolled into the turn I saw a high wing GA aircraft appear at approximately 12:30; and very close.  I immediately brought it to the captain's attention.  As we started to roll wings level to join the SID; we were directly behind the GA AC; closing rapidly both vertically and laterally.  Just prior to taking the AC I glanced down at my instruments and the displays showed the other AC basically superimposed over our AC and at +400. I called for autopilot off FDs off and started lowering the nose to reduce the climb rate; almost immediately we got the RA 'DESCEND...DESCEND'.  As I had the aircraft in sight I decided to roll into a right turn to maneuver away laterally.  This also helped to ease the transition from climb pitch to descent pitch; without excessive G forces.  I continued pushing the nose over in response to the RA and we got 'CLEAR OF CONFLICT'; moments later. I estimate our heading as 30 to 40 right of course and what appeared as a similar change of course for the GA AC but to the left.  I believe that was what resolved the conflict; as the TCAS was reading diverging courses.  Vertical separation was still very close. I don't believe the GA AC was aware of the impending collision and his left turn was related to whatever he was doing; it was just fortunate for both of us that he did.  When the captain told the controller we were responding to RA; the controller responded 'you were told to climb to 2;000' or something to that effect; as though we wouldn't have had a problem at that altitude but my early actions and the subsequent RA occurred at or below 1;000 feet.  When he made that comment; I immediately checked my instruments and we were in level flight at 2;020 feet; right of course.  Further evidence of how quickly things developed is that we got an overspeed warning ie: 280kts below 10;000 feet.  We were focusing all of our attention on the impending midair collision; and as such I failed to reduce to climb thrust and the captain's [situational awareness] didn't catch it either.  If leveling off at 2;000 feet alone was enough to avoid an RA we wouldn't have missed the thrust reduction at 1;000.  By the time the tower controller recleared us to join the SID; I was reducing power to flight idle to get control of our airspeed and started reengaging automation back to SOP's.  We were switched to departure and he queried us about what had occurred.  He said that they also record these events; I assume for the same reasons we do.  The flight continued without further complications.  On a side note; it appeared as though the cabin and passengers were unaware that anything out of the ordinary had occurred as the captain initiated communications post event; not the cabin. I don't know the cause!  I can only surmise that as this was going on for some time and that previous aircraft departing both runways hadn't experienced problems; the controller had no reason to believe we would either.  Apparently; he was convinced the altitude restriction was sufficient to maintain separation.  Had I not seen the +400 on the navigation display; I would have thought that our climb closure rate was what caused the RA but our instruments and our own visual conclusions confirmed that was just not the case!  I know that no one wants to make the decision to shut down operations at an airport but if you consider that departures going East or Westoff 15R cut a rather large swathe maybe someone should.  The GA AC in question and it's unpredictable flight path intersected the departures of multiple AC.  I suppose the argument could be made that we could be guilty of the same thing.  Actually; I can't speak for the captain as I don't know if he was even aware of the transmissions from the GA AC.  I might not have paid attention either but one of the transmissions made it sound like a police chase and my morbid curiosity got the best of me.  I assumed that the altitude restriction was just an overabundance of caution on the controller's part and that his radar showed plenty of lateral clearance along our flight path.  Next time I'll ask!




Synopsis: An air carrier aircraft departed IAH Runway 15R and took evasive action to a TCAS RA 'DESCEND DESCEND' warning during a near miss with a small high wing aircraft in its departure path.