Narrative:

I was working local control during the mid-morning push. We were landing runways 28L/right and departing runways 1 left/right. The weather was VFR and we were running visual approaches. When a H B747 checked in on an 11 mile final; I advised the aircraft not to over take the airbus ahead for the parallel runway and cleared him to land on runway 28L. At this time the B747 was about a mile behind an airbus on a visual approach to runway 28R. At this time the B747 was about 30 KTS faster than the airbus. The B747 did his best to stay behind the airbus and during my scan I noticed the longitudinal distance between the two had decreased but the speeds were matched and the airbus was still ahead. On about a three mile final the B747 called and said 'we're just overtaking that aircraft; we have to.' at this time I sent the B747 around and told him to fly heading 265 and maintain 3;000 ft to get him away from the airbus. The targets on the radar appeared to be even longitudinally. I think the finals could have been better planned and more positive control established prior to giving a communication change to tower frequency. I did my best to rectify the situation; but due to aircraft performance; the 747 was not able to stay behind the other aircraft. I could have issued a go around earlier; however during my scan; I observed matched speeds and thought the B747 could stay behind. I could have told the airbus to keep his speed up; however he was also preceded by a heavy and I did not want to cause an issue with wake turbulence between the the airbus and the preceding arrival.

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Original NASA ASRS Text

Title: Tower Controller at SFO reports sending a B747 around when the pilot is unable to remain behind an A320 landing on the parallel runway.

Narrative: I was working Local Control during the mid-morning push. We were landing Runways 28L/R and departing Runways 1 L/R. The weather was VFR and we were running visual approaches. When a H B747 checked in on an 11 mile final; I advised the aircraft not to over take the airbus ahead for the parallel runway and cleared him to land on Runway 28L. At this time the B747 was about a mile behind an Airbus on a visual approach to Runway 28R. At this time the B747 was about 30 KTS faster than the Airbus. The B747 did his best to stay behind the Airbus and during my scan I noticed the longitudinal distance between the two had decreased but the speeds were matched and the Airbus was still ahead. On about a three mile final the B747 called and said 'We're just overtaking that aircraft; we have to.' At this time I sent the B747 around and told him to fly heading 265 and maintain 3;000 FT to get him away from the Airbus. The targets on the RADAR appeared to be even longitudinally. I think the finals could have been better planned and more positive control established prior to giving a communication change to Tower frequency. I did my best to rectify the situation; but due to aircraft performance; the 747 was not able to stay behind the other aircraft. I could have issued a go around earlier; however during my scan; I observed matched speeds and thought the B747 could stay behind. I could have told the Airbus to keep his speed up; however he was also preceded by a heavy and I did not want to cause an issue with wake turbulence between the the Airbus and the preceding arrival.

Data retrieved from NASA's ASRS site as of April 2012 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.