Narrative:

I was acting as captain on a series of part 121 flts. At an intermediate stop, I returned to the aircraft, after going to operations and obtaining the flight release, checking WX, etc, and was met by an FAA inspector standing in the cockpit. After introductions we proceeded to run all checklist and prepared for departure. I had been experimenting with my battery pwred GPS (global positioning system) unit to test whether or not the unit would work and if so what accuracies would be observed when compared to on board VOR system. The unit I was using is battery pwred, was not attached to any aircraft system and is certified by the FCC as meeting part 15 of the regulations regarding interference. In addition, the unit is FAA approved for aircraft use, through numerous stc's. Considering the above, I assumed that it was perfectly legal to operate the unit, as long as I did not use it for navigation, which I did not. The takeoff and climb out were normal. During the en route phase of flight, we discussed the benefits of GPS including, added safety through increased situational awareness, accuracy of navigation, the possibility of using GPS to satisfy etop's requirements on the 737-300. I also told the inspector that I had done an analysis of the potential economic benefits from using GPS and that FAA administrator had a copy of this report in his office. I do not recall if I explained that this analysis was derived from a historical comparison of romeo 737-300 aircraft to the non romeo 737-200, DC9, MD80 aircraft. The descent was conducted normally with compliance with assigned crossing and speed restrs. The approach phase of the flight was the typical 'slam dunk,' with our being held high and 3 speed changes, we did catch the GS and were spooled and stabilized by 500 ft AGL. A normal landing was made and we taxied to the gate. After completion of the shutdown checklist, the inspector told me not to use the unit and I immediately put the unit up. He then left the aircraft without further comment. The flight was conducted in accordance with normal operating procedures and company policy. At no time was the GPS attached to any aircraft system, at no time was the unit used for navigation or any other function of aircraft operation. And its presence did not interfere any part of the flight. In retrospect, it may not be such a good idea to carry your own 1994 technology to backup your existing 1950's system.

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Original NASA ASRS Text

Title: MLG CAPT PERFORMING HIS OWN HAND HELD GPS CHK IS TOLD BY ACI NOT TO USE THE UNIT.

Narrative: I WAS ACTING AS CAPT ON A SERIES OF PART 121 FLTS. AT AN INTERMEDIATE STOP, I RETURNED TO THE ACFT, AFTER GOING TO OPS AND OBTAINING THE FLT RELEASE, CHKING WX, ETC, AND WAS MET BY AN FAA INSPECTOR STANDING IN THE COCKPIT. AFTER INTRODUCTIONS WE PROCEEDED TO RUN ALL CHKLIST AND PREPARED FOR DEP. I HAD BEEN EXPERIMENTING WITH MY BATTERY PWRED GPS (GLOBAL POSITIONING SYS) UNIT TO TEST WHETHER OR NOT THE UNIT WOULD WORK AND IF SO WHAT ACCURACIES WOULD BE OBSERVED WHEN COMPARED TO ON BOARD VOR SYS. THE UNIT I WAS USING IS BATTERY PWRED, WAS NOT ATTACHED TO ANY ACFT SYS AND IS CERTIFIED BY THE FCC AS MEETING PART 15 OF THE REGULATIONS REGARDING INTERFERENCE. IN ADDITION, THE UNIT IS FAA APPROVED FOR ACFT USE, THROUGH NUMEROUS STC'S. CONSIDERING THE ABOVE, I ASSUMED THAT IT WAS PERFECTLY LEGAL TO OPERATE THE UNIT, AS LONG AS I DID NOT USE IT FOR NAV, WHICH I DID NOT. THE TKOF AND CLB OUT WERE NORMAL. DURING THE ENRTE PHASE OF FLT, WE DISCUSSED THE BENEFITS OF GPS INCLUDING, ADDED SAFETY THROUGH INCREASED SITUATIONAL AWARENESS, ACCURACY OF NAV, THE POSSIBILITY OF USING GPS TO SATISFY ETOP'S REQUIREMENTS ON THE 737-300. I ALSO TOLD THE INSPECTOR THAT I HAD DONE AN ANALYSIS OF THE POTENTIAL ECONOMIC BENEFITS FROM USING GPS AND THAT FAA ADMINISTRATOR HAD A COPY OF THIS RPT IN HIS OFFICE. I DO NOT RECALL IF I EXPLAINED THAT THIS ANALYSIS WAS DERIVED FROM A HISTORICAL COMPARISON OF ROMEO 737-300 ACFT TO THE NON ROMEO 737-200, DC9, MD80 ACFT. THE DSCNT WAS CONDUCTED NORMALLY WITH COMPLIANCE WITH ASSIGNED XING AND SPD RESTRS. THE APCH PHASE OF THE FLT WAS THE TYPICAL 'SLAM DUNK,' WITH OUR BEING HELD HIGH AND 3 SPD CHANGES, WE DID CATCH THE GS AND WERE SPOOLED AND STABILIZED BY 500 FT AGL. A NORMAL LNDG WAS MADE AND WE TAXIED TO THE GATE. AFTER COMPLETION OF THE SHUTDOWN CHKLIST, THE INSPECTOR TOLD ME NOT TO USE THE UNIT AND I IMMEDIATELY PUT THE UNIT UP. HE THEN LEFT THE ACFT WITHOUT FURTHER COMMENT. THE FLT WAS CONDUCTED IN ACCORDANCE WITH NORMAL OPERATING PROCS AND COMPANY POLICY. AT NO TIME WAS THE GPS ATTACHED TO ANY ACFT SYS, AT NO TIME WAS THE UNIT USED FOR NAV OR ANY OTHER FUNCTION OF ACFT OP. AND ITS PRESENCE DID NOT INTERFERE ANY PART OF THE FLT. IN RETROSPECT, IT MAY NOT BE SUCH A GOOD IDEA TO CARRY YOUR OWN 1994 TECHNOLOGY TO BACKUP YOUR EXISTING 1950'S SYS.

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.