Narrative:

Air carrier X dca bos WX conditions at bos were such that catii operations were in we (1200-2000 RVR) briefing on approach was given as per company SOP. The approach was a dual channel autoplt with autoland to runway 4R bos. Boston tower advised that the landing clearance would be delayed because a truck was on the runway and 'he was already halfway down the runway.' the runway environment appeared at approximately 150 ft AGL and I took control of the aircraft as per the briefing. I announced 'landing' and the first officer reminded me we had yet to be cleared by tower. There was quite a bit of 'clutter' on the frequency and I thought I heard 'cleared to land' but we could not verify this because of the clutter. A go around was initiated on the autoplt. As the throttles advanced, contact was made with the main wheels and we became airborne again as tower cleared us to land. The throttles were closed and the landing was made without incident. I believe the missed approach should have been made or initiated sooner on my part. Adding to the problem was the separation on the approach, the numerous needless xmissions on tower frequency and the presence of a vehicle on the active runway during the catii approachs.

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Original NASA ASRS Text

Title: ACR X STARTED GAR BECAUSE OF NO LNDG CLRNC THEN LANDED WHEN LNDG CLRNC ISSUED.

Narrative: ACR X DCA BOS WX CONDITIONS AT BOS WERE SUCH THAT CATII OPS WERE IN WE (1200-2000 RVR) BRIEFING ON APCH WAS GIVEN AS PER COMPANY SOP. THE APCH WAS A DUAL CHANNEL AUTOPLT WITH AUTOLAND TO RWY 4R BOS. BOSTON TWR ADVISED THAT THE LNDG CLRNC WOULD BE DELAYED BECAUSE A TRUCK WAS ON THE RWY AND 'HE WAS ALREADY HALFWAY DOWN THE RWY.' THE RWY ENVIRONMENT APPEARED AT APPROX 150 FT AGL AND I TOOK CTL OF THE ACFT AS PER THE BRIEFING. I ANNOUNCED 'LNDG' AND THE FO REMINDED ME WE HAD YET TO BE CLRED BY TWR. THERE WAS QUITE A BIT OF 'CLUTTER' ON THE FREQ AND I THOUGHT I HEARD 'CLRED TO LAND' BUT WE COULD NOT VERIFY THIS BECAUSE OF THE CLUTTER. A GAR WAS INITIATED ON THE AUTOPLT. AS THE THROTTLES ADVANCED, CONTACT WAS MADE WITH THE MAIN WHEELS AND WE BECAME AIRBORNE AGAIN AS TWR CLRED US TO LAND. THE THROTTLES WERE CLOSED AND THE LNDG WAS MADE WITHOUT INCIDENT. I BELIEVE THE MISSED APCH SHOULD HAVE BEEN MADE OR INITIATED SOONER ON MY PART. ADDING TO THE PROBLEM WAS THE SEPARATION ON THE APCH, THE NUMEROUS NEEDLESS XMISSIONS ON TWR FREQ AND THE PRESENCE OF A VEHICLE ON THE ACTIVE RWY DURING THE CATII APCHS.

Data retrieved from NASA's ASRS site as of July 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.