Sfo controller voiced concern regarding alleged ambiguous visual separation procedures applied by nc...

Narrative:

Both aircraft on final descending about even; maybe air carrier Y .1 mile ahead. Air carrier X asked if air carrier Y was assigned visual separation from them? I advised I was not aware how that was done; just that they were both on visual approaches. Air carrier X acknowledged; then air carrier Y keyed up and said they were not assigned anything. I asked air carrier X if they were assigned visual separation and they said yes. This is a huge problem. If air carrier X joined final slightly ahead of air carrier Y; I would not know that an operator error (oe) has occurred; I would have issued the wake turbulence advisory and let them land. The ambiguous visual separation that nct provides creating situations where aircraft are passing each other and occasionally going around unexpectedly is unsafe at best. This is a link in the chain. I can only imagine the relief the controllers would experience if they were told one-way visuals only that is that! Recommendation; nct should go to consistent one way visual separation on final into sfo to alleviate the ambiguity were aircraft are passing each other established on final.

Original NASA ASRS Text

Title: SFO Controller voiced concern regarding alleged ambiguous visual separation procedures applied by NCT Controller during simultaneous approaches; listing aircraft passing one another as an example.

Narrative: Both aircraft on final descending about even; maybe Air Carrier Y .1 mile ahead. Air Carrier X asked if Air Carrier Y was assigned visual separation from them? I advised I was not aware how that was done; just that they were both on visual approaches. Air Carrier X acknowledged; then Air Carrier Y keyed up and said they were not assigned anything. I asked Air Carrier X if they were assigned visual separation and they said yes. This is a huge problem. If Air Carrier X joined final slightly ahead of Air Carrier Y; I would not know that an Operator Error (OE) has occurred; I would have issued the wake turbulence advisory and let them land. The ambiguous visual separation that NCT provides creating situations where aircraft are passing each other and occasionally going around unexpectedly is unsafe at best. This is a link in the chain. I can only imagine the relief the controllers would experience if they were told one-way visuals only that is that! Recommendation; NCT should go to consistent one way visual separation on final into SFO to alleviate the ambiguity were aircraft are passing each other established on final.

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.

Attributes
ACN	979684
Time
Date	201111
Local Time Of Day	1801-2400
Place
Locale Reference	SFO.Tower
State Reference	CA
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Light Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	IFR
Person 1
Function	Local
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Published Material / Policy

Sfo controller voiced concern regarding alleged ambiguous visual separation procedures applied by nct controller during simultaneous approaches; listing aircraft passing one another as an example.