Narrative:

I was surprised in flight to be informed of a potential pilot deviation for class B airspace entry without clearance. Slc controller asked me to contact them after flight to begin processing investigation paperwork. Synopsis: VFR departure from ogd; I requested 'I-15 VFR corridor south through slc class B;' a common VFR transition I use frequently and that is published on the slc VFR terminal area chart. Ogden tower issued instructions to maintain 5500 ft south over I-15 highway and handed me off to hill AFB tower. Hafb controller also issued 5500 ft and the I-15 track and handed me off to slc approach approximately 12 NM north of slc airport. This was the third controller within 13 miles of takeoff (5 minutes of flight). I advised slc approach I was I-15 southbound at 5500 feet for transition to the south. He gave no indication that I would not be able to proceed on this route; and immediately issued two traffic conflicts. One passing from my left to right was landing at bountiful airport and was at my altitude. Controller suggested 30 degree turn to left to avoid; at which point I caught visual less than 1/2 mile away; co-altitude. This occurred abeam the bountiful airport; 9 NM north of the slc airport. My left turn took me east of I-15 toward mountainous terrain that rises above 5500 ft. After clear of this traffic; I turned back south parallel to I-15. The second conflict; also co-altitude was opposite direction (northbound) in the same VFR corridor. I had visual contact with this traffic by one mile separation and it was less of an issue due to my offset east of the highway. These traffic calls apparently precluded the controller from completing class B clearance for me; yet he still handed me off to slc tower. (Up to this point; my altitude of 5500 feet put me below the floor of the class B; which is 7000 feet along north I-15.) I did not hear (but learned later by phone with the tower supervisor) that the approach controller also issued instructions to remain clear of the class B as he switched me to tower. Unfortunately; at that point on the ground track; even if I had heard his call to remain clear of the class B; I would have been unable to do so. The I-15 corridor for the last 9 nautical miles southbound prior to reaching the slc tower's airspace is too narrow in most places to enable a safe course reversal at 5500 ft. Terrain to the east within 1-2 nautical miles rises rapidly above 5500 ft. Additionally; the class B airspace within 1-2 NM west of the I-15 corridor is surface to 10000 ft. I calculated my 30 degree turn diameter for the density altitude conditions to be 10000 ft (nearly 2 NM). Therefore a right turn takes you into class B airspace and a left turn results in terrain obstructions. Continuing to follow I-15 would result in class B penetration while trying to establish contact with the tower controller. I believed throughout my transmissions with the slc approach controller that slc approach had understood my request for corridor transition and that by handling me with traffic calls that there was no issue with my intentions. However; the tower controller viewed me as an aircraft entering his airspace without prior clearance. I believe the immediate cause of this inadvertent and apparent airspace incursion is the high number of traffic controller hand-offs (tower was the fourth controller I had to talk to within 7 minutes from takeoff). Secondly; given the tight constraints of the corridor; and the difficulty in reversing course for the 9 NM stretch prior to tower's airspace; a clearance into class B needs to be confirmed well north of the tower handoff. That clearance needs to be the first priority of the initial contact with slc approach; in order for the pilot to have options to remain clear when such clearance is not available. A potential solution that would have mitigated this problem would be to establish standard altitudes for separation of traffic in the corridor (ie 5500 ft southbound and 6500 ft northbound) unless directed otherwise by ATC. A procedure like this would relieve the controller's numerous traffic calls; and would have left the approach controller more time to provide the completed class B clearance and not rely on tower to make the clearance; when it's too late to turn around. Furthermore; a procedure should be considered to allow the hill AFB tower and/or ogden tower to provide clearance into class B along the corridor so that even more lead time is available for alternatives. Four controllers over a 20 NM distance is too many to enable the controllers time needed when they are also issuing traffic calls. Most importantly; every time I have used the corridor; I have confronted opposite direction traffic; co altitude. This is a very hazardous situation in a narrow corridor and deserves immediate consideration of establishing different altitudes (as mentioned above) for north versus southbound aircraft. Human performance considerations: simultaneous traffic avoidance maneuvering and numerous controller hand-offs were task saturating to the point that 'lack of class B airspace clearance' was not even noticed.

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Original NASA ASRS Text

Title: SMA ACFT EXPERIENCED SLC CLASS B INCURSION; CLAIMING MULTIPLE FREQ CHANGES AND UNCLEAR ATC HANDLING AS CONTRIBUTING FACTORS.

Narrative: I WAS SURPRISED IN FLIGHT TO BE INFORMED OF A POTENTIAL PILOT DEVIATION FOR CLASS B AIRSPACE ENTRY WITHOUT CLEARANCE. SLC CONTROLLER ASKED ME TO CONTACT THEM AFTER FLIGHT TO BEGIN PROCESSING INVESTIGATION PAPERWORK. SYNOPSIS: VFR DEPARTURE FROM OGD; I REQUESTED 'I-15 VFR CORRIDOR SOUTH THROUGH SLC CLASS B;' A COMMON VFR TRANSITION I USE FREQUENTLY AND THAT IS PUBLISHED ON THE SLC VFR TERMINAL AREA CHART. OGDEN TOWER ISSUED INSTRUCTIONS TO MAINTAIN 5500 FT SOUTH OVER I-15 HIGHWAY AND HANDED ME OFF TO HILL AFB TOWER. HAFB CONTROLLER ALSO ISSUED 5500 FT AND THE I-15 TRACK AND HANDED ME OFF TO SLC APPROACH APPROXIMATELY 12 NM NORTH OF SLC AIRPORT. THIS WAS THE THIRD CONTROLLER WITHIN 13 MILES OF TAKEOFF (5 MINUTES OF FLIGHT). I ADVISED SLC APPROACH I WAS I-15 SOUTHBOUND AT 5500 FEET FOR TRANSITION TO THE SOUTH. HE GAVE NO INDICATION THAT I WOULD NOT BE ABLE TO PROCEED ON THIS ROUTE; AND IMMEDIATELY ISSUED TWO TRAFFIC CONFLICTS. ONE PASSING FROM MY LEFT TO RIGHT WAS LANDING AT BOUNTIFUL AIRPORT AND WAS AT MY ALTITUDE. CONTROLLER SUGGESTED 30 DEG TURN TO LEFT TO AVOID; AT WHICH POINT I CAUGHT VISUAL LESS THAN 1/2 MILE AWAY; CO-ALTITUDE. THIS OCCURRED ABEAM THE BOUNTIFUL AIRPORT; 9 NM NORTH OF THE SLC AIRPORT. MY LEFT TURN TOOK ME EAST OF I-15 TOWARD MOUNTAINOUS TERRAIN THAT RISES ABOVE 5500 FT. AFTER CLEAR OF THIS TRAFFIC; I TURNED BACK SOUTH PARALLEL TO I-15. THE SECOND CONFLICT; ALSO CO-ALTITUDE WAS OPPOSITE DIRECTION (NORTHBOUND) IN THE SAME VFR CORRIDOR. I HAD VISUAL CONTACT WITH THIS TRAFFIC BY ONE MILE SEPARATION AND IT WAS LESS OF AN ISSUE DUE TO MY OFFSET EAST OF THE HIGHWAY. THESE TRAFFIC CALLS APPARENTLY PRECLUDED THE CONTROLLER FROM COMPLETING CLASS B CLEARANCE FOR ME; YET HE STILL HANDED ME OFF TO SLC TOWER. (UP TO THIS POINT; MY ALTITUDE OF 5500 FEET PUT ME BELOW THE FLOOR OF THE CLASS B; WHICH IS 7000 FEET ALONG NORTH I-15.) I DID NOT HEAR (BUT LEARNED LATER BY PHONE WITH THE TOWER SUPERVISOR) THAT THE APPROACH CONTROLLER ALSO ISSUED INSTRUCTIONS TO REMAIN CLEAR OF THE CLASS B AS HE SWITCHED ME TO TOWER. UNFORTUNATELY; AT THAT POINT ON THE GROUND TRACK; EVEN IF I HAD HEARD HIS CALL TO REMAIN CLEAR OF THE CLASS B; I WOULD HAVE BEEN UNABLE TO DO SO. THE I-15 CORRIDOR FOR THE LAST 9 NAUTICAL MILES SOUTHBOUND PRIOR TO REACHING THE SLC TOWER'S AIRSPACE IS TOO NARROW IN MOST PLACES TO ENABLE A SAFE COURSE REVERSAL AT 5500 FT. TERRAIN TO THE EAST WITHIN 1-2 NAUTICAL MILES RISES RAPIDLY ABOVE 5500 FT. ADDITIONALLY; THE CLASS B AIRSPACE WITHIN 1-2 NM WEST OF THE I-15 CORRIDOR IS SURFACE TO 10000 FT. I CALCULATED MY 30 DEG TURN DIAMETER FOR THE DENSITY ALTITUDE CONDITIONS TO BE 10000 FT (NEARLY 2 NM). THEREFORE A RIGHT TURN TAKES YOU INTO CLASS B AIRSPACE AND A LEFT TURN RESULTS IN TERRAIN OBSTRUCTIONS. CONTINUING TO FOLLOW I-15 WOULD RESULT IN CLASS B PENETRATION WHILE TRYING TO ESTABLISH CONTACT WITH THE TOWER CONTROLLER. I BELIEVED THROUGHOUT MY TRANSMISSIONS WITH THE SLC APPROACH CONTROLLER THAT SLC APPROACH HAD UNDERSTOOD MY REQUEST FOR CORRIDOR TRANSITION AND THAT BY HANDLING ME WITH TRAFFIC CALLS THAT THERE WAS NO ISSUE WITH MY INTENTIONS. HOWEVER; THE TOWER CONTROLLER VIEWED ME AS AN AIRCRAFT ENTERING HIS AIRSPACE WITHOUT PRIOR CLEARANCE. I BELIEVE THE IMMEDIATE CAUSE OF THIS INADVERTENT AND APPARENT AIRSPACE INCURSION IS THE HIGH NUMBER OF TRAFFIC CONTROLLER HAND-OFFS (TOWER WAS THE FOURTH CONTROLLER I HAD TO TALK TO WITHIN 7 MINUTES FROM TAKEOFF). SECONDLY; GIVEN THE TIGHT CONSTRAINTS OF THE CORRIDOR; AND THE DIFFICULTY IN REVERSING COURSE FOR THE 9 NM STRETCH PRIOR TO TOWER'S AIRSPACE; A CLEARANCE INTO CLASS B NEEDS TO BE CONFIRMED WELL NORTH OF THE TOWER HANDOFF. THAT CLEARANCE NEEDS TO BE THE FIRST PRIORITY OF THE INITIAL CONTACT WITH SLC APPROACH; IN ORDER FOR THE PILOT TO HAVE OPTIONS TO REMAIN CLEAR WHEN SUCH CLEARANCE IS NOT AVAILABLE. A POTENTIAL SOLUTION THAT WOULD HAVE MITIGATED THIS PROBLEM WOULD BE TO ESTABLISH STANDARD ALTITUDES FOR SEPARATION OF TRAFFIC IN THE CORRIDOR (IE 5500 FT SOUTHBOUND AND 6500 FT NORTHBOUND) UNLESS DIRECTED OTHERWISE BY ATC. A PROCEDURE LIKE THIS WOULD RELIEVE THE CONTROLLER'S NUMEROUS TRAFFIC CALLS; AND WOULD HAVE LEFT THE APPROACH CONTROLLER MORE TIME TO PROVIDE THE COMPLETED CLASS B CLEARANCE AND NOT RELY ON TOWER TO MAKE THE CLEARANCE; WHEN IT'S TOO LATE TO TURN AROUND. FURTHERMORE; A PROCEDURE SHOULD BE CONSIDERED TO ALLOW THE HILL AFB TOWER AND/OR OGDEN TOWER TO PROVIDE CLEARANCE INTO CLASS B ALONG THE CORRIDOR SO THAT EVEN MORE LEAD TIME IS AVAILABLE FOR ALTERNATIVES. FOUR CONTROLLERS OVER A 20 NM DISTANCE IS TOO MANY TO ENABLE THE CONTROLLERS TIME NEEDED WHEN THEY ARE ALSO ISSUING TRAFFIC CALLS. MOST IMPORTANTLY; EVERY TIME I HAVE USED THE CORRIDOR; I HAVE CONFRONTED OPPOSITE DIRECTION TRAFFIC; CO ALTITUDE. THIS IS A VERY HAZARDOUS SITUATION IN A NARROW CORRIDOR AND DESERVES IMMEDIATE CONSIDERATION OF ESTABLISHING DIFFERENT ALTITUDES (AS MENTIONED ABOVE) FOR NORTH VERSUS SOUTHBOUND AIRCRAFT. HUMAN PERFORMANCE CONSIDERATIONS: SIMULTANEOUS TRAFFIC AVOIDANCE MANEUVERING AND NUMEROUS CONTROLLER HAND-OFFS WERE TASK SATURATING TO THE POINT THAT 'LACK OF CLASS B AIRSPACE CLEARANCE' WAS NOT EVEN NOTICED.

Data retrieved from NASA's ASRS site as of May 2009 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.