Narrative:

Cleared direct sbono and descend to 7000 feet on the RNAV visual 13R. Approximately 6-8 miles past sbono; with the airport and terrain in sight; I initiated a descent to 4000 feet believing the controller had issued us clearance for the RNAV visual. Passing through approximately 6700 feet the controller asked for confirmation of altitude and indicated that the minimum vectoring altitude was 7000 feet. I corrected pitch and power to recover quickly to 7000 feet. Prior to reaching 7000 feet the controller asked if we had the field in sight; we responded we did and for what I thought was the second time issued approach clearance. I then corrected to descend to 4000 feet approaching totav. The airport and terrain was in sight throughout the sequence of events and the rest of the approach and landing was uneventful.in hindsight; after mentally reviewing the sequence of events; I believe the controller may have said 'direct sbono and descend to 7000 feet for the RNAV visual' and I incorrectly interpreted that as approach clearance. While I had no doubt that we had received clearance I had reviewed both the 19-0-1 and 19-0 pages; and briefed the procedure. All that said I would suggest this is a case where I should re-confirm approach clearance prior to leaving 7000 feet.

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Original NASA ASRS Text

Title: Flight crew misunderstood ATC routing and altitude clearance for the expected approach procedure. ATC alerted the crew to the fact that they had descended below minimum vectoring altitude. The crew regained the assigned altitude and completed the approach and landing uneventfully.

Narrative: Cleared direct SBONO and descend to 7000 feet on the RNAV Visual 13R. Approximately 6-8 miles past SBONO; with the airport and terrain in sight; I initiated a descent to 4000 feet believing the controller had issued us clearance for the RNAV Visual. Passing through approximately 6700 feet the controller asked for confirmation of altitude and indicated that the minimum vectoring altitude was 7000 feet. I corrected pitch and power to recover quickly to 7000 feet. Prior to reaching 7000 feet the controller asked if we had the field in sight; we responded we did and for what I thought was the second time issued approach clearance. I then corrected to descend to 4000 feet approaching TOTAV. The airport and terrain was in sight throughout the sequence of events and the rest of the approach and landing was uneventful.In hindsight; after mentally reviewing the sequence of events; I believe the controller may have said 'Direct SBONO and descend to 7000 feet FOR the RNAV Visual' and I incorrectly interpreted that as approach clearance. While I had no doubt that we had received clearance I had reviewed both the 19-0-1 and 19-0 pages; and briefed the procedure. All that said I would suggest this is a case where I should re-confirm approach clearance prior to leaving 7000 feet.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.