Narrative:

This is a tale of three ATC facilities: bay approach, oak center and stockton approach. Three yrs ago, each was a highly trained, extraordinarily effective unit. Our aircraft could arrive and depart our home base of oak with ease. Today, the rules have changed and one item got overlooked that needs to be fixed. Three yrs ago, a jet aircraft arriving from the south would be assigned the panoche 2 arrival (pxn, karnn bored bushy sunol, final approach for 27R oak). We would be talking to oak center until handed off to bay approach. An aircraft arriving from the east would be assigned the madwin 3 arrival (over eca locke sunol final for 27R). We would speak to oak center and then bay approach on 135.4, then 134.5. An aircraft arriving from the north would generally arrive over sau and be assigned a heading of 120 or so for a downwind to either take the visual to 27R or the ILS to 27R. Again, oak center to bay approach. It was a well thought-out, efficient process. Then things changed. Somewhere in ATC a bad idea was born: to reduce the workload for aircraft arriving sfo, the oak and sjc arrivals can be pushed down into stockton approach's airspace and they can 'pre-sort' and sequence them for oak, so then we had to speak to two approach control facilities versus center to one approach. On checking in with sck, they would logically give us the sck altimeter setting. When we approached bay's airspace, we were handed off from stockton to bay about the catty intersection. Then one more issue came about which caused the compromise in safety: consolidation of apches into what is now known as norcal. Now that they are all one facility, there is a critical error in programming which must be addressed and changed. Usually, on descending, we would obtain the ATIS from 150 NM or so out and set the landing altimeter once passing through FL180. When traffic began to be shoved down early to get into stockton's airspace, sck issued the sck altimeter. When we were handed off to bay, we would announce that we had the landing ATIS with bay and they would sequence us for arrival. Now that they are all one facility, they dropped a very critical item. Normally, we provide the ATIS code to the landing approach control facility: norcal. In this case however, they will give us the sck altimeter setting when approaching from either south or east. Since they are all one facility, the initial controller accepts our having received the ATIS call, but expects us to set the sck altimeter for his sector in the ca valley. On contacting 135.4 there is no mention of changing to the landing altimeter setting. Because of the topography and WX patterns characteristic to ca in this region, it is more then likely that the altimeter settings between oak and sck will be different, sometimes largely so. This could obviously cause problems during an instrument approach in terms of terrain separation, but traffic poses a greater threat in this case. Often VFR traffic departing hayward will fly directly under the final approach course to the oak north field. IFR traffic arriving from the north on the vector heading of approximately 120 degrees from sau passes right over this corridor by 1000 ft when heading to either the 27's or runway 29 at oak (mostly air carrier Y B737's). So add up: altimeters off by 75 ft but legal, altimeter settings different by 200 ft, altimeter setting is up to 1 hour old, and less than perfect altitude control by the pilot equals loss of separation. In any event, norcal needs to tighten up the communications procedure. Either go back to the far superior old method of oak center until approaching the class B airspace (higher apches since the traffic flow is much reduced at sfo) or ensure the controller who coordinates the old traditional 'bay approach' gate by livermore makes a statement to the effect of 'changed to oak altimeter setting now.' yes, that increases his workload, but better than having aircraft create a loss of separation due to vague altimeter assignments.

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Original NASA ASRS Text

Title: OAK BASED PLT EXPRESSED CONCERN REGARDING NCT'S ALTIMETER SETTING ISSUANCE PROC FOR OAK ARRS.

Narrative: THIS IS A TALE OF THREE ATC FACILITIES: BAY APCH, OAK CENTER AND STOCKTON APCH. THREE YRS AGO, EACH WAS A HIGHLY TRAINED, EXTRAORDINARILY EFFECTIVE UNIT. OUR ACFT COULD ARRIVE AND DEPART OUR HOME BASE OF OAK WITH EASE. TODAY, THE RULES HAVE CHANGED AND ONE ITEM GOT OVERLOOKED THAT NEEDS TO BE FIXED. THREE YRS AGO, A JET ACFT ARRIVING FROM THE SOUTH WOULD BE ASSIGNED THE PANOCHE 2 ARR (PXN, KARNN BORED BUSHY SUNOL, FINAL APCH FOR 27R OAK). WE WOULD BE TALKING TO OAK CENTER UNTIL HANDED OFF TO BAY APCH. AN ACFT ARRIVING FROM THE E WOULD BE ASSIGNED THE MADWIN 3 ARR (OVER ECA LOCKE SUNOL FINAL FOR 27R). WE WOULD SPEAK TO OAK CENTER AND THEN BAY APCH ON 135.4, THEN 134.5. AN ACFT ARRIVING FROM THE N WOULD GENERALLY ARRIVE OVER SAU AND BE ASSIGNED A HEADING OF 120 OR SO FOR A DOWNWIND TO EITHER TAKE THE VISUAL TO 27R OR THE ILS TO 27R. AGAIN, OAK CENTER TO BAY APCH. IT WAS A WELL THOUGHT-OUT, EFFICIENT PROCESS. THEN THINGS CHANGED. SOMEWHERE IN ATC A BAD IDEA WAS BORN: TO REDUCE THE WORKLOAD FOR ACFT ARRIVING SFO, THE OAK AND SJC ARRIVALS CAN BE PUSHED DOWN INTO STOCKTON APCH'S AIRSPACE AND THEY CAN 'PRE-SORT' AND SEQUENCE THEM FOR OAK, SO THEN WE HAD TO SPEAK TO TWO APCH CTL FACILITIES VERSUS CENTER TO ONE APCH. ON CHECKING IN WITH SCK, THEY WOULD LOGICALLY GIVE US THE SCK ALTIMETER SETTING. WHEN WE APCHED BAY'S AIRSPACE, WE WERE HANDED OFF FROM STOCKTON TO BAY ABOUT THE CATTY INTXN. THEN ONE MORE ISSUE CAME ABOUT WHICH CAUSED THE COMPROMISE IN SAFETY: CONSOLIDATION OF APCHES INTO WHAT IS NOW KNOWN AS NORCAL. NOW THAT THEY ARE ALL ONE FAC, THERE IS A CRITICAL ERROR IN PROGRAMMING WHICH MUST BE ADDRESSED AND CHANGED. USUALLY, ON DSNDING, WE WOULD OBTAIN THE ATIS FROM 150 NM OR SO OUT AND SET THE LNDG ALTIMETER ONCE PASSING THROUGH FL180. WHEN TFC BEGAN TO BE SHOVED DOWN EARLY TO GET INTO STOCKTON'S AIRSPACE, SCK ISSUED THE SCK ALTIMETER. WHEN WE WERE HANDED OFF TO BAY, WE WOULD ANNOUNCE THAT WE HAD THE LNDG ATIS WITH BAY AND THEY WOULD SEQUENCE US FOR ARR. NOW THAT THEY ARE ALL ONE FACILITY, THEY DROPPED A VERY CRITICAL ITEM. NORMALLY, WE PROVIDE THE ATIS CODE TO THE LNDG APCH CTL FACILITY: NORCAL. IN THIS CASE HOWEVER, THEY WILL GIVE US THE SCK ALTIMETER SETTING WHEN APCHING FROM EITHER S OR E. SINCE THEY ARE ALL ONE FACILITY, THE INITIAL CTLR ACCEPTS OUR HAVING RECEIVED THE ATIS CALL, BUT EXPECTS US TO SET THE SCK ALTIMETER FOR HIS SECTOR IN THE CA VALLEY. ON CONTACTING 135.4 THERE IS NO MENTION OF CHANGING TO THE LNDG ALTIMETER SETTING. BECAUSE OF THE TOPOGRAPHY AND WX PATTERNS CHARACTERISTIC TO CA IN THIS REGION, IT IS MORE THEN LIKELY THAT THE ALTIMETER SETTINGS BTWN OAK AND SCK WILL BE DIFFERENT, SOMETIMES LARGELY SO. THIS COULD OBVIOUSLY CAUSE PROBS DURING AN INSTRUMENT APCH IN TERMS OF TERRAIN SEPARATION, BUT TFC POSES A GREATER THREAT IN THIS CASE. OFTEN VFR TFC DEPARTING HAYWARD WILL FLY DIRECTLY UNDER THE FINAL APCH COURSE TO THE OAK N FIELD. IFR TFC ARRIVING FROM THE N ON THE VECTOR HEADING OF APPROX 120 DEGS FROM SAU PASSES RIGHT OVER THIS CORRIDOR BY 1000 FT WHEN HEADING TO EITHER THE 27'S OR RWY 29 AT OAK (MOSTLY ACR Y B737'S). SO ADD UP: ALTIMETERS OFF BY 75 FT BUT LEGAL, ALTIMETER SETTINGS DIFFERENT BY 200 FT, ALTIMETER SETTING IS UP TO 1 HR OLD, AND LESS THAN PERFECT ALTITUDE CTL BY THE PLT EQUALS LOSS OF SEPARATION. IN ANY EVENT, NORCAL NEEDS TO TIGHTEN UP THE COMS PROCEDURE. EITHER GO BACK TO THE FAR SUPERIOR OLD METHOD OF OAK CENTER UNTIL APCHING THE CLASS B AIRSPACE (HIGHER APCHES SINCE THE TFC FLOW IS MUCH REDUCED AT SFO) OR ENSURE THE CTLR WHO COORDINATES THE OLD TRADITIONAL 'BAY APCH' GATE BY LIVERMORE MAKES A STATEMENT TO THE EFFECT OF 'CHANGED TO OAK ALTIMETER SETTING NOW.' YES, THAT INCREASES HIS WORKLOAD, BUT BETTER THAN HAVING ACFT CREATE A LOSS OF SEPARATION DUE TO VAGUE ALTIMETER ASSIGNMENTS.

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.