Date: 201406
Local time of day: 0601-1200
Location: P50.TRACON, AZ
Flight conditions: VMC
Weather elements / visibility: 45
Light: Daylight
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class D IWA
ATC / advisory: TRACON P50
Second aircraft: Aerobatic
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Flight Engineer; Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor
Human factors: Distraction; Situational Awareness
Second reporter function: Captain; Pilot Not Flying
Anomaly: Conflict Airborne Conflict
Detector: Automation Aircraft TA; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action
Contributing factors: Airport; Airspace Structure; Human Factors
Primary problem: Airspace Structure

Narrative: As we approached TYLIK intersection we were told of traffic at our 11 o'clock maneuvering. We stated that we were looking. I spotted the traffic maneuvering and it was an aerobatic aircraft changing altitude and direction quickly. ATC told us to turn left to a heading 220. We complied. Now traffic was at our 12 o'clock and I told the Captain I had the aircraft in sight and recommended he turn right and descend to avoid the traffic. He said he did not see the traffic but I should do what I think is right. I disconnected the autopilot contacted ATC and told them we were turning right to avoid traffic. They agreed and then stated that they had a traffic alert. I maneuvered our aircraft to the right and descended about 500 feet to avoid the other aircraft.Aerobatic aircraft maneuver too fast for TCAS to be of any use other than a TA. An RA can change from a climb to a descent so fast that it's beyond the capabilities of our aircraft to change its direction along with TA commands. We experience too many near midairs near IWA involving flights. We should either change our arrival/departure procedures or move the aerobatic aircraft out of the area. There will be a collision at some point. You can't have that many RAs in one area without eventually causing loss of life.


Second narrative: In the past; scenarios like this have resulted in late TCAS RAs with vertical instructions to 'Climb' followed almost immediately with instructions to 'Descend now.' These reversal instructions are very difficult to follow without fairly significant control inputs that can alarm passengers.Due to the high level of commercial traffic; training aircraft and acrobatic aircraft in and around the Class D airspace of IWA; and the zero control outside of Class D airspace directly outside of IWA yet within the departure and arrival routes of commercial aircraft; and due to the extra congestion of traffic flying low near and around IWA in an attempt to fly VFR below the shelf of PHX Class B airspace that hangs over and around IWA; it is my recommendation; again; that this airspace is more carefully controlled via Class C airspace classification to improve the safety of the airspace around IWA for departing and arriving commercial air carrier aircraft as well as private; training and acrobatic aircraft.


Synopsis: A commercial fixed wing jet approaching IWA took evasive action to avoid an aerobatic aircraft just outside the Class D ring. Reporters advised these conflicts are frequent.