Date: 201911
Local time of day: 0601-1200
Location: LGA.Tower, NY
Aircraft: Medium Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Final Approach
Airspace: Class B LGA
ATC / advisory: Tower LGA
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Situational Awareness
Anomaly: Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented
Contributing factors: Human Factors; Procedure
Primary problem: Ambiguous

Narrative: We arrived in LGA with clear skies within the Class B airspace. We were assigned the Expressway Visual 31 approach. We briefed the non-standard descent and configuration changes. I was backing up my First Officer (FO) with the recommended crossing altitudes as we were approaching airport. Tower cleared us to continue at 900 ft. MSL as number 3 for the runway. We continued our approach but only configured to gear down and flaps 30 until we were assured we could land. We still had the turn to final around Citi Field. At 600 ft. MSL or so we were cleared to land 31. We selected flaps 45. We ran the Before Landing Checklist. When I finished the checklist we were below 500 ft. MSL at approximately 400 ft. MSL. We were also completing our rollout onto final approach at this point. The LGA Expressway Visual 31 approach is a non-standard circling style approach. Because the altitude at the turn to final I consider this to be a somewhat unstable approach in practice. I have only flown this a couple of times over the years and did not remember much besides the visual references. Since we were circling to 31; we held final configuration changes and checklist till we knew that landing was assured. We were slightly high at first and during the turn onto final saw we were slightly low. I was transitioning inside and outside making alignment and descent call outs to the Pilot Flying as his view of the airport was restricted during the turn to final. I did not look at the altitude while running the Landing Check. When I made the '500 Stable; Continue' callout a second or so later I saw we were at 400 MSL or so. At this point we were in a position to make a normal landing using normal maneuvers. With the non-standard nature of this approach and the high workload I don't know if we completed the final configuration before 500 ft. MSL. It wasn't until after landing that the realization occurred. If we had a landing clearance earlier; I would have had us configure earlier on the base to final turn. In the future I will configure before 1000 ft. AGL even though this is a circling maneuver. The workload backing up the Pilot Flying on this particular approach is too high when close in to the runway to finish the final configuration change and checklist.




Synopsis: Captain reported an altitude deviation and momentary unstable condition during rollout on final approach course for the Expressway Visual RWY 31 to LaGuardia airport.