Air carrier flight crew reported transitioning from the msy rythm arrival to the runway 20 RNAV at 2...

Attributes
ACN	1444102
Time
Date	201704
Local Time Of Day	0601-1200
Place
Locale Reference	MSY.Airport
State Reference	LA
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	STAR RYTHM
Flight Plan	IFR
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Type 1479
Events
Anomaly	ATC Issue All Types Airspace Violation All Types Deviation - Procedural FAR Deviation - Procedural Published Material / Policy Deviation - Speed All Types

Narrative:

We were coming into msy on the rythm arrival; which ties directly to the RNAV 20. Sometime around oysty; approach cleared us to 2000 feet; slowed us to 210; and cleared us for the approach. We were in IMC. We descended to be outside jaspo (the FAF) at 2000. This resulted in us getting down to 2000 prior to 15 NM from msy (outside the class B); doing about 210 knots. When we got to rayop; approach said; you are reentering the class B. Oh. Whoops. Class B excursion. This whole class B thing has become such an issue that I don't even know what is right anymore. Clearly we were speeding below the lateral limits. However; I was under the impression that the class B excursions have been occurring during visual approaches; where the pilots are operating on their own recognizance; and descend too soon. In this case; we under ATC control; on an instrument approach; and in IMC. The controller gave us a clearance below the floor of the class B; and at a high speed. I didn't think they were supposed to do that; especially since we were at an ATC assigned speed too high for that position. Are we really supposed to be trapping this type of ATC error too; without the tools to do so? So maybe he did that on purpose; I just don't understand what's going on. And if he did; he did not warn us that we might go out the bottom; and he didn't tell us when we did so.

Original NASA ASRS Text

Title: Air carrier flight crew reported transitioning from the MSY RYTHM Arrival to the Runway 20 RNAV at 2;000 feet and were notified reentering Class B . The crew was not aware the aircraft was below Class B at 210 knots in IMC.

Narrative: We were coming into MSY on the RYTHM arrival; which ties directly to the RNAV 20. Sometime around OYSTY; Approach cleared us to 2000 feet; slowed us to 210; and cleared us for the approach. We were in IMC. We descended to be outside JASPO (the FAF) at 2000. This resulted in us getting down to 2000 prior to 15 NM from MSY (outside the Class B); doing about 210 knots. When we got to RAYOP; Approach said; you are reentering the Class B. Oh. Whoops. Class B excursion. This whole Class B thing has become such an issue that I don't even know what is right anymore. Clearly we were speeding below the lateral limits. However; I was under the impression that the Class B excursions have been occurring during VISUAL approaches; where the pilots are operating on their own recognizance; and descend too soon. In THIS case; we under ATC control; on an instrument approach; and in IMC. The controller gave us a clearance below the floor of the Class B; and at a high speed. I didn't think they were supposed to do that; especially since we were at an ATC assigned speed too high for that position. Are we really supposed to be trapping this type of ATC error too; without the tools to do so? So maybe he did that on purpose; I just don't understand what's going on. And if he did; he did not warn us that we might go out the bottom; and he didn't tell us when we did so.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Air carrier flight crew reported transitioning from the msy rythm arrival to the runway 20 RNAV at 2;000 feet and were notified reentering class B . The crew was not aware the aircraft was below class B at 210 knots in IMC.