Flight Crew Instrument; Flight Crew Commercial; Flight Crew Flight Instructor
Flight Crew Last 90 Days 63; Flight Crew Total 730; Flight Crew Type 65
Communication Breakdown; Situational Awareness
ATC Issue All Types; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance
Human Factors
I was piloting an aircraft with two passengers aboard. The passenger in the right seat was an A&P and student pilot with over 40 hours of flight training. The passenger in the back was a multi-thousand hour commercial pilot and flight instructor with a significant amount of IFR experience; especially into and around HEF. Our IFR flight to HEF was coming to an end as we were being stepped down and vectored from the west onto the ILS 16L approach into HEF. We were working with Potomac Approach on 128.525 MHz at the time. Regarding altitude; I was first directed to descend from 4;000 feet MSL to 3;000 feet MSL; after which I read back and initiated the descent. Shortly after I was directed to descend from 3;000 feet MSL to 2;000 feet MSL; which I also read back and initiated. Passing through 2;200 feet I was contacted by the controller who asked what I was doing; and then informed that I was to only descend to 2;600 feet. When replying that I had heard an assigned altitude of 2;000 feet; I was then informed that we were below the sector's minimum vectoring altitude and asked if I was able to maintain visual separation with the terrain. Being in solid IMC I replied in the negative; and immediately initiated a climb back to 2;600 feet. Both of my passengers- each with a unique degree of aviation experience- attested to having also heard an assigned altitude of 2;000 feet. Soon afterwards we were cleared for the approach and the flight concluded uneventfully.
On approach to HEF in IMC; there was a breakdown in communication about an assigned altitude between the pilot and the Controller.