Date: 201504
Local time of day: 1801-2400
Location: I90.TRACON, TX
Flight conditions: IMC
Light: Dusk
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B IAH
ATC / advisory: TRACON I90
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Confusion; Situational Awareness; Workload
Anomaly: ATC Issue All Types; Conflict Airborne Conflict
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Became Reoriented
Contributing factors: Airspace Structure; Procedure; Airport
Primary problem: Procedure

Narrative: I decided to add an addendum to my originally filed report. The events on the original report are true to the best of my recollection; but I wanted to add a few things.   First of all; the alleged 'pilot deviation; resulting in a loss of separation;' was in my opinion no loss of separation at all; as both aircraft in question were tracking their respective localizers; at their assigned altitudes; and at their assigned airspeeds.  In my opinion; if that constitutes a loss of separation; then it is the ATC system that is faulty. My conversation with the TRACON controller was professional and courteous.  He tried to explain to me that triple simultaneous ILS approaches were similar to Precision Runway Monitor (PRM) approaches.  I'm not sure I still understand his explanation; but it seems to me that this environment is vastly different than the standard ILS environment at IAH.  Additionally; if the triple simultaneous approach environment is that different; then why don't we have additional information in the approach pages referencing said differences?  Furthermore; if my flight resulted in a 'loss of separation;' what about the flight before me; or the one after; or the one after that? I'm fairly certain they were they were flying their approaches in the same manner.  This seems to be a case of ATC making special requirements; to make it legal to operate triple simultaneous approaches; but not disseminating that information to the pilots.  During my conversation; with the controller; He even admitted that 'the issue is partially on us.' He further stated that maybe we need to change the verbiage in our communication; to something like; 'contact Houston tower NOW.'(Emphasis added)  Once again it would appear that this triple simultaneous approach environment is rife with potential 'gotchas.'  In my opinion; as well as the opinion of every other pilot I have spoken with about this event believe this setup should be suspended until proper operational procedures are vetted and implemented.I hold myself to a very high standard; as do all my colleagues; but we are only human; and as such; mistakes happen.  But I would ask; how can you know you're making a mistake when you don't know the rule?




Synopsis: A pilot reported confusion about a conflict which IAH ATC alleged during a triple simultaneous ILS approach where no special procedures are specified different from standard ILS approaches.