Date: 201812
Local time of day: 1201-1800
Location: MIA.TRACON, FL
Flight conditions: VMC
Light: Daylight
Aircraft: EMB-505 / Phenom 300
Operator: Air Taxi
Operating under: Part 91
Flight phase: Cruise
Airspace: Class B MIA
ATC / advisory: TRACON MIA
Reporter organization: Air Taxi
Reporter function: Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Situational Awareness; Confusion
Second reporter function: First Officer; Pilot Flying
Anomaly: ATC Issue All Types; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural FAR
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Human Factors; Procedure
Primary problem: Human Factors

Narrative: Traversing the MIA Class B airspace at 4;000 feet; we were at 250 kts. Prior to penetrating the southern shelf of the airspace; over Miami Executive Airport (Class B 7000 to 5000); we slowed to 200 knots. MIA APP issued clearance to maintain 250 knots. I responded unable due to being below Class B; can only do 200 knots. Controller said maintain 210 [knots] or greater. I replied with clearance but we maintained 200 knots. Soon thereafter; we were once again in [Class] B and accelerated to 250 knots. We switched to another Approach Controller and entered the northern lower shelf of B; so we slowed to 200. The new controller also gave us a clearance to accelerate to 250 or we would be number 3 for the airport. I once again replied unable due to being below Class B. He asked what speed I could do; to which I said 200 [knots]. He said maintain 200 [knots] or greater. I have heard of this occurring before; but why are controllers not familiar with their airspace and FARs that govern them? Twice; by two separate controllers; we were issued a clearance that was a clear violation of FARs. The southern shelf above Miami Executive Airport is probably there for local traffic. There is a reason why we should be at 200 knots instead of 250.


Second narrative: During the flight; we were traveling under Class B in the southwest and northwest sections of Miami Class B airspace. Before entering those areas; we slowed to 200 knots. On two separate occasion on the same flight; the controllers asked us to speed up which would have exceeded our speed limitation under Class B. We advised both controllers that we would be unable to comply and we remained at 200 knots. The first controller's response in the southwest section was to maintain 210 knots or better after we had already notified him we were unable comply due to being under Class B. We continued to maintain 200 knots. Second controller asked to maintain 200 knots or better. We remain at 200 knots until either exiting Class B or we entered Class B airspace. As a crew we did not violate the regulation concerning under Class B speed limitation. Suggestion is to follow the regulations and notify Controller anytime they may be requesting us to deviate from the regulation.


Synopsis: EMB 505 flight crew reported ATC issued clearance for speeds higher then 200 knots while below the MIA Class Bravo airspace.