Small Aircraft; Low Wing; 2 Eng; Retractable Gear
Flight Crew Commercial; Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 100; Flight Crew Total 1300; Flight Crew Type 400
Communication Breakdown; Confusion
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Flight Crew Returned To Clearance
Human Factors; Procedure
While descent into West Hope; North Dakota I requested a cruise clearance as no instrument approach procedure exists and I was unable to descend below the clouds at my current altitude. It was my understanding that a cruise clearance would let a pilot determine his own minimum IFR altitude; therefore allowing descent below the MVA. I was in contact with Minot Approach and requested cruise 3;000. The Controller said unable; so I asked for cruise 3;600; my current altitude. He gave me cruise 3;600. At that point I began a descent below 3;600 on my way down to the appropriate IFR altitude of 1;000 FT above the highest obstacle.When I was at roughly 3;200 FT I was asked to say altitude. I told them and was instructed to immediately climb to 3;600. I was told I could not descent below 3;600 as that was their MVA. However they had still issued me a cruise clearance. I climbed back up to 3;600 and diverted to Bottineau; North Dakota since I could no longer get into West Hope. I spoke to the controllers and tried to explain how I thought a cruise clearance worked. I am still not sure I was incorrect in my descent below 3;600. It appeared that there was a trainee controller and a supervisor. I landed in D09 without further incident.
Pilot attempting to land at an airport without an IFR procedure descends below assigned altitude assuming he has permission to do so; which is below the MVA for the airport area.