Date: 201604
Local time of day: 1201-1800
Location: S46.TRACON, WA
Flight conditions: VMC
Light: Daylight
Aircraft: Airbus Industrie Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Climb
Airspace: Class B SEA
ATC / advisory: TRACON S46
Second aircraft: B737 Undifferentiated or Other Model
Reporter organization: Government
Reporter function: Departure
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Detector: Person Air Traffic Control
Result: Air Traffic Control Separated Traffic; Air Traffic Control Issued New Clearance
Contributing factors: Procedure; Airspace Structure; Aircraft
Primary problem: Procedure

Narrative: Working Departure sector. Gorgeous VMC. Please reference previous reports for an identical event that occurred approximately 15 minutes earlier. The SOP allows ATCT to launch successive departures utilizing pilot provided visual separation. The ATCT must modify the secondary scratchpad in the data-tag to advise the TRACON that pilot provided visual separation is being used. However; in this case the first aircraft is an [airbus model aircraft] and that type of aircraft is notorious for climbing out much slower than most other aircraft. According to the FALCON replay; the trailing [B737] is 1.95 miles behind the [Airbus] with approximately a 30 knot overtake. In light of the situation that had already occurred; I stopped the [B737] at 3;000 feet on the climbout. I do not recall if I restricted his speed; but I believe that I did (230 knots).Immediately after observing this situation developing; I flipped on our stop departure lights to terminate automatic releases. I simultaneously made the supervisor aware of the new situation. A final aircraft departed behind the [B737]; a [large transport]. Because the [large transport] was airborne; I decided to turn the [B737] out to the northwest in an attempt to give myself some room to work. I also restricted the [large transport] to 4;000 feet on initial contact to ensure vertical separation between the [large transport] and the [Airbus]; in case that became an overtake situation as well. All aircraft subsequently continued their departures without further incident.This is a common problem that we experience with the [Airbus model] departures. I do not know why this specific aircraft type climbs out so differently; but it is common knowledge at the TRACON. I would propose that this situation could be corrected by changing the LOA to exclude [this specific model] departures from the provision allowing the use of pilot provided visual separation between successive departures. If ATCT had utilized the standard 3-5 mile in-trail spacing that would have been required this event would have been completely avoided.




Synopsis: S46 TRACON Controller reported an Airbus departure climbed at a much slower airspeed than subsequent departures requiring ATC to restrict and vector off course the trailing aircraft.