A B737-300 FLC COMPLIED WITH A TWR REQUESTED RWY CHANGE AND WERE MET BY FAA INSPECTORS WHO FELT THAT IT HAD BEEN AN UNSTABILIZED APCH.

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DURING APCH (ILS RWY 33) TO BOS; TWR REQUESTED THAT WE LAND ON RWY 27. SINCE WE WERE 5 NM FROM THE FIELD AND APPROX 1500 FT; THE CAPT AND I FELT THE LNDG COULD BE SAFELY MADE. WE RESPONDED THAT WE COULD LAND ON RWY 27 AND TWR GRANTED LNDG CLRNC. THE ILS FREQ FOR RWY 27 WAS SET TO ASSIST IN THE VISUAL APCH TO RWY 27. THE APCH WAS NOT RUSHED AND LOOKED SIMILAR TO THE WASHINGTON; DC; RIVER VISUAL RWY 19 APCH; IN THAT THE ACFT MUST BE TURNED OR IN TURNING FLT AT 300-400 FT AGL TO ALIGN THE ACFT WITH RWY. THE LNDG WAS NICE AND WE THOUGHT NOTHING MORE OF THE APCH. 3 FAA PERSONNEL VIEWED THE APCH AND WERE CONCERNED THAT THE ACFT WAS NOT STABILIZED AT 500 FT. AGAIN; THE APCH WAS LIKE THE WASHINGTON; DC; RIVER VISUAL RWY 19 APCH IN WHICH YOU CAN'T BE STABILIZED AT 500 FT FOR A VISUAL APCH. ONE OF THE FAA PERSONNEL MET THE CAPT AT THE JETWAY TO DISCUSS THE APCH. IN THIS EVENT THE CTLRS HAD TFC CONGESTION ON ONE RWY AND REQUESTED WE LAND ON ANOTHER RWY TO REDUCE THE CONGESTION. I KNOW BOTH PLTS AND THE CTLR FELT THE REQUEST WAS TIMELY AND COULD SAFELY BE ACCOMPLISHED. IN THE END; A SAFE LNDG WAS ACCOMPLISHED BUT REQUIRED TURNING FLT BELOW 500 FT; A NORMAL PROC TO DCA RWY 19; BUT NOT AT BOS ARPT. PLTS AND CTLRS ARE PERFORMANCE ORIENTED AND WILL TRY TO MAXIMIZE OR OPTIMIZE EACH AND EVERY SOLUTION REQUIRED. IN THIS CASE; A 50 DEG HDG CHANGE HAD TO BE ACCOMPLISHED TO LAND. BASED ON BANK ANGLE LIMITATIONS AND SPD CONSTRAINTS; A CALCULATION CAN EASILY BE MADE; ACCOUNTING FOR PLT REACTION TIME; TO DETERMINE THE DME AT WHICH A PLT CAN MAKE THE HDG CHANGE AND BE STABILIZED BY 500 FT. OUTSIDE THAT DME; THE REQUEST TO LAND ON A DIFFERENT RWY CAN BE MADE. INSIDE THAT DME; THE CTLR WILL HAVE TO ACCEPT THE SIT OR SEND THE ACFT AROUND. THIS WOULD CLRLY ELIMINATE ACFT NOT BEING STABILIZED BY 500 FT WHILE LNDG ON A DIFFERENT RWY THAN INITIALLY PLANNED! CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE APCH WAS REVIEWED BY THE ACR'S FLT OPS STAFF AND DISCUSSED WITH THE FLC. THE APCH; AS FLOWN; WAS NOT WITHIN THE ACR'S SPECS.