A321
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action; Flight Crew Became Reoriented
Airport; Procedure; Human Factors
We were told by approach control to expect an ILS to 04R. We were then told to expect a visual to 04L and given a vector to be followed by a clearance direct to Boston. We were then asked to report the airport AND traffic off to our right. There were several targets and we informed ATC that we were unable to determine which aircraft they wanted us to report. We were then issued a clearance to turn right to 090 degrees. When I initiated the turn it became very apparent which aircraft they wanted us to see because there was a [large transport aircraft] right in front of us on approach to 04R. I immediately turned the autopilot off and corrected left to avoid a collision with the jet (Aircraft Y). We received a TCAS TA at about the same time I clicked the autopilot off. That approach contained the most mishandled and dangerous clearances I have ever experienced in my entire aviation career.I called the TRACON supervisor to find out why this event occurred. He informed me that there was a trainee controller on both 04L AND 04R and they had issued us a 190 speed in error which put us out in front of Aircraft Y; which is why we didn't see him. He then issued us a 170 speed so Aircraft Y would overtake us. The problem was Aircraft Y had not overtaken us completely when he issued the heading of 090. I then asked why we were not staggered like SFO does. The supervisor informed me they do not stagger in BOS and try and put us wingtip to wingtip. That does not seem like the safest course of action to me. Do not have trainees working two parallel runways at the same time. In addition do not change runway clearances at the last minute. I would also suggest that with close together runways such as 04L and 04R in BOS that we are staggered so as never to be wingtip to wingtip in case someone overshoots the turn or maybe doesn't see the aircraft ATC wants you to see because they are behind you.
A321 Captain reported a side by side approach with another large turbojet to Runways 4L and 4R that he believed was not safe but was reported as standard practice at BOS.