Narrative:

I was the trainer watching the trainee work local. The trainee was doing an excellent job and required no corrective action. I was not even aware that there was a loss of separation until after I was off position for about 30 minutes. After reviewing the computer playback; I saw that the trainee had cleared aircraft X for takeoff. And after waiting for what appeared to be the proper time and spacing; he then cleared aircraft Y for takeoff. Aircraft X tagged up on our radar scope indicating 160 kts of airspeed. This is normal for most of the jets that takeoff from sfo. Aircraft Y tagged up more than 3 miles behind aircraft X and about the same airspeed. And aircraft X was about two or three thousand feet above aircraft Y. So it appeared we had more than standard radar separation and more than the required vertical separation. Both aircraft were switched to norcal TRACON in a timely manner and nothing seemed out of the ordinary. I cannot say exactly what led to the event; but it would appear that nct is willfully not separating aircraft; and are waiting for aircraft to loose separation and then telling sfo that they would like more spacing.recommend that sfo and nct get together and work out some sort of LOA or SOP for the spacing they would like for aircraft Y aircraft behind the aircraft X type. Perhaps we could try 4 miles; and see how that works. And if that is not satisfactory then we could increase it another mile until we come to some agreement as to what would work best for the safe; orderly and expeditious flow of traffic. Also recommend that they could install the spacing or safety bats on the departures (like there is on the arrivals) so that we could have a visual cue as to when aircraft might be in danger of loosing proper spacing. This is already on the arrivals; why then is it not also on the departing aircraft; especially since this seems to be an ongoing problem. It would help us here at sfo to warn nct when these situations are emerging. And if they were also on the nct scopes; then it would help them recognize that a loss of separation was about to occur.

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Original NASA ASRS Text

Title: SFO Local Controller reports of two aircraft that were a loss of separation in NCT's airspace. Controller gave more than minimum distance between the aircraft and more then 1;000 FT of separation. NCT Controller reports of a loss of separation on departure between two aircraft that should have been 7 miles apart opposed to 3 miles for same fix separation.

Narrative: I was the trainer watching the trainee work local. The trainee was doing an excellent job and required no corrective action. I was not even aware that there was a loss of separation until after I was off position for about 30 minutes. After reviewing the computer playback; I saw that the trainee had cleared Aircraft X for takeoff. And after waiting for what appeared to be the proper time and spacing; he then cleared Aircraft Y for takeoff. Aircraft X tagged up on our radar scope indicating 160 kts of airspeed. This is normal for most of the jets that takeoff from SFO. Aircraft Y tagged up more than 3 miles behind Aircraft X and about the same airspeed. And Aircraft X was about two or three thousand feet above Aircraft Y. So it appeared we had more than standard radar separation and more than the required vertical separation. Both aircraft were switched to Norcal TRACON in a timely manner and nothing seemed out of the ordinary. I cannot say exactly what led to the event; but it would appear that NCT is willfully not separating aircraft; and are waiting for aircraft to loose separation and then telling SFO that they would like more spacing.Recommend that SFO and NCT get together and work out some sort of LOA or SOP for the spacing they would like for Aircraft Y aircraft behind the Aircraft X type. Perhaps we could try 4 miles; and see how that works. And if that is not satisfactory then we could increase it another mile until we come to some agreement as to what would work best for the safe; orderly and expeditious flow of traffic. Also recommend that they could install the spacing or safety bats on the departures (like there is on the arrivals) so that we could have a visual cue as to when aircraft might be in danger of loosing proper spacing. This is already on the arrivals; why then is it not also on the departing aircraft; especially since this seems to be an ongoing problem. It would help us here at SFO to warn NCT when these situations are emerging. And if they were also on the NCT scopes; then it would help them recognize that a loss of separation was about to occur.

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.