Learjet 35
Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Flight Crew Last 90 Days 50; Flight Crew Total 25000; Flight Crew Type 8000
ATC Issue All Types; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action
Human Factors
Approach Control issued a descent and heading. We read back 2;000 and continued. Shortly thereafter we were switched to another controller and we replied with the heading and 2;000 feet again. Sometime later as we descended we were asked what our altitude was and we replied 2;600. We were told to climb to 3;000 which we did. Then were told that they usually issued 4;000 in our position. Weather was clear and although I thought the altitude was a little low we had the field in site from more than 20 miles out.A conversation with ATC revealed they had only issued 6;000 feet. and they twice failed to catch it on read back. I would hope that ATC would catch a questionable read back and a lower altitude than normal much quicker.
We were issued a descent down to what we had thought was two thousand feet. I read back to the controller that we were descending down to two thousand feet and the controller didn't say anything about it. The controller then came back and gave us another vector and I said again the heading in which he told me and said we were descending to two thousand. As we got to around 2;700-2;600 the controller came back and said we should have been at 4;000 and then told us to climb to 3;000 for the visual approach.
The flight crew of a LR35 descended below the ATC cleared altitude due to a communication breakdown during issuance and read back.