Narrative:

As I approached runway 17 at yum MCAS, I was instructed to 'taxi into position and hold.' at this time, nor at any time thereafter, was any advisory of another traffic operating on the crossing runway 03L issued to me. As I taxied onto the runway, I understood a clearance for takeoff and authorization to 'depart westbound as requested,' or words to that effect. (I had previously indicated to the tower controller my direction of departure.) shortly after my takeoff clearance and while still on the takeoff run, I received instructions that I understood as 'maintain 700',' which I read back to the controller. At the time I was airborne or shortly before, I spotted a hover jet off my right side, at the approach end of runway 03L. At that point the jet appeared to be hovering and momentarily the traffic began slowly traveling down runway 03L. At all time, visibility contact was maintained with the jet. I further estimate that we didn't come within dangerous closeness to the jet. Climbing on runway heading (170 degrees) until reaching and maintain 700' MSL, I started my right turn toward the west. Shortly after I had established the aircraft on a heading of 260 degrees, the tower controller informed that I was instructed to 'climb straight out.' I then replied my understanding as 'departure as requested, maintain 700'.' I was surprised and apologized to the controller for the deviation. A few seconds later he asked for my name and home base; I complied. Given my surprise and the facility that I never perceived any imminent danger throughout the maneuver, I inquired the controller as to any conflicts that might have been triggered as a result of my operation. He then stated that I was never cleared for the takeoff. I responded consistently with what I just mentioned above. After the departure I continued to squawk code 0440, which had been assigned to me on my arrival while receiving radar services. I arrived at yum MCAS just about 5 mins before the departure in question. After departure I proceeded into mexico following my DVFR flight plan previously filed (destination was ensenada, mexico). I elected not to request radar services from yum due to the close proximity of the mexican border. After approximately 10 mins and while over mexican airspace, I discovered the wrong transponder code and rest it to 1200. I operate very frequently in and out of the yum MCAS and I have not experienced and such incidents there. I attribute this operational error (if in fact I deviated from ATC instructions) to the fact that I was running slightly behind schedule, and perhaps I was operating in a hasty manner. Yum MCAS is a very busy and complex facility. Their mix of GA and military aircraft is quite diverse. Communications can become a problem due to the multiple frequencys a controller has to handle, and also the unique problem of having several different aircraft operating within a confined environment using different frequencys. The important communication edge gained by listening on the frequency what the other traffic are saying is practically lost here. I agree that controllers, military and civilian pilots should be specially cautious when operating in environments as this, lest there be misunderstandings and possible hazardous encounters.

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Original NASA ASRS Text

Title: SMA PLT COMPLAINT OF FREQ MIX AS WELL AS TRAFFIC MIX AT A MIL ARPT. CITES EXISTING CONDITIONS AS BEING CONTRIBUTORY TO HIS EXECUTING AN UNAUTH TKOF AND DEVIATION FROM CLRNC. DURING THIS EVENT HE CREATED A POTENTIAL CONFLICT LESS THAN STANDARD SEPARATION WITH A JET OPERATING ON A CROSSING RWY.

Narrative: AS I APCHED RWY 17 AT YUM MCAS, I WAS INSTRUCTED TO 'TAXI INTO POS AND HOLD.' AT THIS TIME, NOR AT ANY TIME THEREAFTER, WAS ANY ADVISORY OF ANOTHER TFC OPERATING ON THE XING RWY 03L ISSUED TO ME. AS I TAXIED ONTO THE RWY, I UNDERSTOOD A CLRNC FOR TKOF AND AUTHORIZATION TO 'DEPART WBND AS REQUESTED,' OR WORDS TO THAT EFFECT. (I HAD PREVIOUSLY INDICATED TO THE TWR CTLR MY DIRECTION OF DEP.) SHORTLY AFTER MY TKOF CLRNC AND WHILE STILL ON THE TKOF RUN, I RECEIVED INSTRUCTIONS THAT I UNDERSTOOD AS 'MAINTAIN 700',' WHICH I READ BACK TO THE CTLR. AT THE TIME I WAS AIRBORNE OR SHORTLY BEFORE, I SPOTTED A HOVER JET OFF MY RIGHT SIDE, AT THE APCH END OF RWY 03L. AT THAT POINT THE JET APPEARED TO BE HOVERING AND MOMENTARILY THE TFC BEGAN SLOWLY TRAVELING DOWN RWY 03L. AT ALL TIME, VIS CONTACT WAS MAINTAINED WITH THE JET. I FURTHER ESTIMATE THAT WE DIDN'T COME WITHIN DANGEROUS CLOSENESS TO THE JET. CLBING ON RWY HDG (170 DEGS) UNTIL REACHING AND MAINTAIN 700' MSL, I STARTED MY RIGHT TURN TOWARD THE W. SHORTLY AFTER I HAD ESTABLISHED THE ACFT ON A HDG OF 260 DEGS, THE TWR CTLR INFORMED THAT I WAS INSTRUCTED TO 'CLB STRAIGHT OUT.' I THEN REPLIED MY UNDERSTANDING AS 'DEP AS REQUESTED, MAINTAIN 700'.' I WAS SURPRISED AND APOLOGIZED TO THE CTLR FOR THE DEVIATION. A FEW SECS LATER HE ASKED FOR MY NAME AND HOME BASE; I COMPLIED. GIVEN MY SURPRISE AND THE FAC THAT I NEVER PERCEIVED ANY IMMINENT DANGER THROUGHOUT THE MANEUVER, I INQUIRED THE CTLR AS TO ANY CONFLICTS THAT MIGHT HAVE BEEN TRIGGERED AS A RESULT OF MY OPERATION. HE THEN STATED THAT I WAS NEVER CLRED FOR THE TKOF. I RESPONDED CONSISTENTLY WITH WHAT I JUST MENTIONED ABOVE. AFTER THE DEP I CONTINUED TO SQUAWK CODE 0440, WHICH HAD BEEN ASSIGNED TO ME ON MY ARR WHILE RECEIVING RADAR SVCS. I ARRIVED AT YUM MCAS JUST ABOUT 5 MINS BEFORE THE DEP IN QUESTION. AFTER DEP I PROCEEDED INTO MEXICO FOLLOWING MY DVFR FLT PLAN PREVIOUSLY FILED (DEST WAS ENSENADA, MEXICO). I ELECTED NOT TO REQUEST RADAR SVCS FROM YUM DUE TO THE CLOSE PROX OF THE MEXICAN BORDER. AFTER APPROX 10 MINS AND WHILE OVER MEXICAN AIRSPACE, I DISCOVERED THE WRONG XPONDER CODE AND REST IT TO 1200. I OPERATE VERY FREQUENTLY IN AND OUT OF THE YUM MCAS AND I HAVE NOT EXPERIENCED AND SUCH INCIDENTS THERE. I ATTRIBUTE THIS OPERATIONAL ERROR (IF IN FACT I DEVIATED FROM ATC INSTRUCTIONS) TO THE FACT THAT I WAS RUNNING SLIGHTLY BEHIND SCHEDULE, AND PERHAPS I WAS OPERATING IN A HASTY MANNER. YUM MCAS IS A VERY BUSY AND COMPLEX FAC. THEIR MIX OF GA AND MIL ACFT IS QUITE DIVERSE. COMS CAN BECOME A PROB DUE TO THE MULTIPLE FREQS A CTLR HAS TO HANDLE, AND ALSO THE UNIQUE PROB OF HAVING SEVERAL DIFFERENT ACFT OPERATING WITHIN A CONFINED ENVIRONMENT USING DIFFERENT FREQS. THE IMPORTANT COM EDGE GAINED BY LISTENING ON THE FREQ WHAT THE OTHER TFC ARE SAYING IS PRACTICALLY LOST HERE. I AGREE THAT CTLRS, MIL AND CIVILIAN PLTS SHOULD BE SPECIALLY CAUTIOUS WHEN OPERATING IN ENVIRONMENTS AS THIS, LEST THERE BE MISUNDERSTANDINGS AND POSSIBLE HAZARDOUS ENCOUNTERS.

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.