Narrative:

I was at the controls and the first officer was handling the radio. We were tracking inbound on a charted radial expecting the mount vernon visual approach. We were held up higher than usual due to traffic and were in marginal VMC (essentially IMC) even though we had some visibility and intermittent ground contact. Rather suddenly, without asking us about our flight conditions or whether we had any landmarks in sight, the controller cleared us for the mount vernon visual, and the first officer acknowledged the clearance. I had the chart in front of me and noted the next checkpoint on the radial (a DME fix) was charted with what looked like an MEA of 2500' so I left last assigned altitude of 4000' and began a descent for the approach. I suddenly realized that I couldn't make the visual approach without the landmark or field in sight and asked for an ILS or assigned lower altitude so I could continue inbound. The controller then asked us (rather after the fact) whether or not we had the river or field in sight. He seemed surprised when we said no and gave us vectors around for the ILS. Complacency was the cause of this incident. The controller's assumption that all inbound flts could see the field or at least the river was no warranted. We, on the other hand, were lulled into descending in marginal conditions on a visual approach because the charted values gave an IFR sense to the maneuver. Fewer assumptions about flight conditions by the controllers and more vigilance on the part of the pilots would minimize such occurrences.

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Original NASA ASRS Text

Title: ACR ACCEPTED A VISUAL APCH WHILE STILL IN IMC CONDITIONS.

Narrative: I WAS AT THE CONTROLS AND THE F/O WAS HANDLING THE RADIO. WE WERE TRACKING INBND ON A CHARTED RADIAL EXPECTING THE MOUNT VERNON VISUAL APCH. WE WERE HELD UP HIGHER THAN USUAL DUE TO TFC AND WERE IN MARGINAL VMC (ESSENTIALLY IMC) EVEN THOUGH WE HAD SOME VISIBILITY AND INTERMITTENT GND CONTACT. RATHER SUDDENLY, WITHOUT ASKING US ABOUT OUR FLT CONDITIONS OR WHETHER WE HAD ANY LANDMARKS IN SIGHT, THE CTLR CLRED US FOR THE MOUNT VERNON VISUAL, AND THE F/O ACKNOWLEDGED THE CLRNC. I HAD THE CHART IN FRONT OF ME AND NOTED THE NEXT CHECKPOINT ON THE RADIAL (A DME FIX) WAS CHARTED WITH WHAT LOOKED LIKE AN MEA OF 2500' SO I LEFT LAST ASSIGNED ALT OF 4000' AND BEGAN A DSCNT FOR THE APCH. I SUDDENLY REALIZED THAT I COULDN'T MAKE THE VISUAL APCH WITHOUT THE LANDMARK OR FIELD IN SIGHT AND ASKED FOR AN ILS OR ASSIGNED LOWER ALT SO I COULD CONTINUE INBND. THE CTLR THEN ASKED US (RATHER AFTER THE FACT) WHETHER OR NOT WE HAD THE RIVER OR FIELD IN SIGHT. HE SEEMED SURPRISED WHEN WE SAID NO AND GAVE US VECTORS AROUND FOR THE ILS. COMPLACENCY WAS THE CAUSE OF THIS INCIDENT. THE CTLR'S ASSUMPTION THAT ALL INBND FLTS COULD SEE THE FIELD OR AT LEAST THE RIVER WAS NO WARRANTED. WE, ON THE OTHER HAND, WERE LULLED INTO DESCENDING IN MARGINAL CONDITIONS ON A VISUAL APCH BECAUSE THE CHARTED VALUES GAVE AN IFR SENSE TO THE MANEUVER. FEWER ASSUMPTIONS ABOUT FLT CONDITIONS BY THE CTLRS AND MORE VIGILANCE ON THE PART OF THE PLTS WOULD MINIMIZE SUCH OCCURRENCES.

Data retrieved from NASA's ASRS site as of August 2007 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.