Flight Crew Air Transport Pilot (ATP)
Workload; Confusion; Communication Breakdown
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR
Air Traffic Control Issued New Clearance; Flight Crew Returned To Clearance; Flight Crew Became Reoriented
Airspace Structure; Human Factors; Procedure
Approaching [our destination] ATC advised us to expect a visual approach to runway XX. Upon checking the runway length it was determine to be too short for landing. We ask for RWY YY. ATC replied unable there is a disabled aircraft on runway YY. Flight crew advised the passengers and decided to go to our alternate TEB. ATC instructed us to turn right heading 040 and descend to 2000 ft. We read back clearance and advised ATC of our intentions to divert. Sometime later a new controller comes on the frequency and advises us to return to 3000 feet while we were descending through 2500 ft. We advised him that we were cleared to 2000 ft and he said that 3000 ft was their minimum vectoring altitude in our sector. Turned the autopilot off and began a climb back to 3000 ft.Approach radar caught us descending below 3000 feet.Too many things going on with [our intended destination] runway closure; attempting to get aircraft to fly the quiet visual approach to 19 at Teterboro. Multiple pilots/aircraft not accepting the quiet visual approach overloading ATC. ATC then changed the approach to the ILS 19. Approach control had many unusual events happening on a busy Sunday afternoon. The runway closure at [our intended destination]; pilots not accepting the Quiet Visual Approach to RWY 19 at Teterboro; plus the volume of traffic.
[Report narrative contained no additional information.]
A Fractional Flight Crew reported descending below 3;000 ft; the floor of the Class B airspace; while on approach to TEB.