C421 FLC DISPUTE DVT TWR POS VERIFICATION AFTER DEPARTING SDL.

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DEPARTED SDL VIA RWY 3; L DOWNWIND DEP; FOR DVT IN VFR CONDITIONS. SDL TWR APPROVED A FREQ CHANGE ABOUT 2 MI SW OF SDL; AND WE ATTEMPTED TO CONTACT DVT TWR. SEVERAL ATTEMPTS WERE MADE; WITH NO RESPONSE. AS WE WERE APCHING HWY 51; STILL S OF BELL ROAD; AND WELL OUTSIDE THE DVT CLASS D AIRSPACE; WE TURNED L TO REMAIN CLR OF THE CLASS D AIRSPACE. SHORTLY THEREAFTER; WHILE HDG S; WE ESTABLISHED CONTACT WITH DVT TWR; WHILE STILL OUTSIDE THE CLASS D AIRSPACE; VERIFIED BY BOTH VISUAL POS AND COMPARISON TO THE PHX TERMINAL AREA CHART; WITH ADDITIONAL VERIFICATION BY A GPS UNIT; WHICH ALSO SHOWED US TO BE OUTSIDE THE DEER VALLEY CLASS D AIRSPACE. ON INITIAL CONTACT; THE CTLR REQUESTED THAT WE IDENT ON OUR XPONDER. THE ATC SPECIALIST THEN STATED THAT OUR POS WAS '2 MI S ' AND THAT IT WAS 'A POSSIBLE VIOLATION.' AT THE TIME; WE WERE 5-6 MI S OF DVT ARPT; AND OUTSIDE THE CLASS D AIRSPACE. HE FURTHER INSTRUCTED US TO 'TURN L; ENTER L BASE; CLRED TO LAND RWY 25L.' WE CONTINUED THE L TURN WE WERE ALREADY IN; AND PROCEEDED INBOUND TO THE ARPT ON A LONG L BASE LEG; SUBSEQUENTLY LNDG. WE DID NOT OBJECT TO THE CTLR'S STATEMENT THAT WE WERE '2 MI S;' BECAUSE HE SOUNDED TIRED AND SOMEWHAT GRUFF. IN LATER DISCUSSIONS WITH OTHER ATC SPECIALISTS; WE WERE TOLD THAT IT IS BEST TO IMMEDIATELY RESPOND TO ANY SUCH STATEMENTS OR IMPROPER INSTRUCTIONS; IN ORDER THAT OUR OBJECTIONS ARE ON THE TAPE; AS WELL AS THE CTLR'S STATEMENTS OR INSTRUCTIONS. IN THE FUTURE; WE WILL BE SURE TO DO SO; RATHER THAN TRYING TO BE AMENABLE IN SUCH A SIT. THE BASIS FOR THE CTLR'S ESTIMATE OF OUR POS IS UNCLR. DVT HAS A VFR ONLY TWR; WITH A BRITE SCOPE REPEATER CHANNELED FROM LUKE AFB; ABOUT 10 MI SW OF DEER VALLEY ARPT. HOWEVER; AS A VFR TWR; I HAVE BEEN INFORMED THAT THE BRITE SCOPE IS NOT CERTIFIED FOR ATC; AND THAT TWR PERSONNEL AT DVT ARE NOT CERTIFIED ON RADAR. ALSO; THE POSITIONING AND CALIBRATION OF THE MAP ON THE BRITE SCOPE MAY BE QUESTIONABLE; IF THIS IS THE SOURCE OF HIS POS ESTIMATE (SINCE WE WERE AT LEAST 3-4 MI MORE DISTANT THAN THE CTLR STATED). IT IS MY UNDERSTANDING THAT LUKE APCH WAS NOT MANNED OR OPERATING AT THAT HR ON SUNDAY NIGHT. THIS SIT OCCURRED AT NIGHT; WITH ONLY OUR NAV LIGHTS (WINGTIP AND TAIL POS LIGHTS) AND ANTICOLLISION LIGHTS ILLUMINATED (LNDG LIGHTS WERE NOT ON); AT AN ALT OF 2500 FT MSL; AGAINST A BACKDROP OF HIGHER MOUNTAINS WITH MANY HOUSES AND OTHER LIGHTED BUILDINGS THEREON; MAKING A VISUAL DISTANCE ESTIMATE TO AN AIRBORNE OBJECT IN A TURN VERY DIFFICULT. WE ARE FAMILIAR WITH THE AREA AND ITS AIRSPACE BOUNDARIES; AND WERE INTENT ON REMAINING OUTSIDE THE CLASS D AIRSPACE UNTIL ESTABLISHING CONTACT AND RECEIVING CLRNC.