Small Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 100; Flight Crew Total 8000; Flight Crew Type 800
Communication Breakdown; Situational Awareness
ATC Issue All Types
Air Traffic Control Issued New Clearance
Procedure; Human Factors
Between VNY and DARTS on the FERN5 arrival; was issued descent from 7000 to 5000 by SoCal Appr ctrl. Descended to 5000; reported SMO in sight. A few miles before DARTS was told to turn to heading 160; intercept rwy 21 final approach course; cleared visual approach to RWY 21; Santa Monica. Made the turn to 160 to intercept the rwy 21 extended centerline. After I intercepted the 21 visual final app course was asked very shortly thereafter by SoCal if I was making the descent for the visual approach. Replied in the affirmative. Seconds later was told by SoCal; in a very AGITATED voice; to 'expedite below 4000'. I did. Switched to tower when told; and landed uneventfully.The problem here is confusion over the altitude assignment and the visual approach clearance. Once the controller cleared me for the visual approach to SMO 21; the manner in which I safely descend to the glide slope and ultimately the runway is up to me. If the controller wanted me at 4000 feet ASAP; he should have issued the instructions 'descend to 4000; cleared visual approach...' But he did not. He left me at 5000; gave me a vector toward final; cleared me for the visual; and then got heated over the radio when I did not descend when he thought I should have. Unnecessary and unclear radio comms from the controller; and interference with my flying of the approach. Not safe.
Pilot was on a visual approach to SMO Runway 21; but SoCal Approach apparently expected him to expedite his descent and then instructed him to do so.