Turboprop twin pilot reports inadvertently loading the RNAV RWY 6 approach into the FMS instead of the intended LDA RWY 6 at ROA. The 200 FT difference between MDA DA results in two missed approaches before the error is discovered and a safe landing ensued after the third approach.

Narrative

I loaded the RNAV (GPS) 6 approach in the FMS when it should have been the LDA Runway 6 approach. During the approach into ROA the visibility was very good and the ceiling low. I was given the LDA Runway 6 approach and vectored to join the approach. I made the approach to Runway 6 using the approach plate for RNAV (GPS) 6 and with the RNAV (GPS) 6 approach loaded in the FMS. The inbound course of the approaches are the same; but with slightly different descent altitudes for the fixes. The minimums for this approach is 200 FT higher than the LDA Runway 6 approach. I had good ground in the broken layer of clouds; but no forward visibility at the MAP; so I executed the missed. I did not see the runway lights; paint or pavement at the MAP; but I did see Runway 6; but not in enough time to make a safe approach to land. I was instructed to fly the published missed. During the approach; the Tower Controller said it looked like I was just north of the course. I said I was exactly on according to my instruments. During the missed; the Controller asked if I was flying the published missed. I said that I was and was handed off to Departure. Departure asked if anything was wrong; I said no; that it was that I couldn't see the runway until I was over it. They asked if I could have made it and I said no. I was vectored around for another approach. I flew the approach to minimums without seeing any reference to the runway that would allow me to continue the approach to land; so I went missed on the second approach as well. On the third approach I was vectored and cleared for the approach by a different Controller. I was advised that I was a certain distance from the fix RAMKE and should be at 4300 FT until crossing. I advised ATC that I was just inside CLAMM and was descending to 2760 FT. It was at this instant that we both realized I was flying one approach all the while ATC was thinking I was flying the LDA Runway 6 approach. They are very close; but the MDA for the LDA approach is 200 FT lower. This is the reason I was not seeing the runway in time to land. Visibility was good below the clouds and the clouds were just over the approach end of Runway 6. I always had good visibility of Runway 33 on each approach and after informing ATC of this; I was cleared to circle to land on Runway 33; which was a non-event. It was discovered when ATC made the reference to RAMKE; a fix on the LDA Runway 6 approach. I allowed the owner (an instrument rated SEL pilot) to work the radio and load the approach into the FMS. I should have done both these. On the first two approaches; ATC never made the first reference to a fix. I was given a vector to join the approach and an altitude to maintain until I was established. This didn't cause me to load the approach in error at all; but I (and ATC) would have caught my mistake on the first approach. I executed poor judgment in not verifying the assigned approach and allowing the owner/pilot to do the radio work. It is my habit to double and triple check everything I do and to repeat back the name of the approach and the runway number. The non-flying pilot doing the radio work did not do this. By repeating the name of the approach; ATC would have caught my mistake; immediately. I am at fault here because I failed to correct the owner/pilot (and my employer) in the manner in which he repeated instructions; which only left ATC to assume we were flying the assigned approach. I discussed at length with the owner/pilot the importance of properly reading back all ATC instructions that included headings; altitudes; names of the approaches and the runway number. I explained the importance of double and triple checking everything we do. This is what I neglected to do before this trip started. We also defined 'exact' cockpit duties. We had a trip the next day in the congested East coast and before the trip started we brief what our duties would be. I worked all the radios and navigation during the departure and approach phases of the flight; and the owner/pilot worked the radio enroute.