MD80 RETURNS TO PBI; FL; FOR SMOKE IN THE COCKPIT.

Narrative

ON CLB AT APPROX 14500 FT; WHITE SMOKE WAS DETECTED IN THE COCKPIT. BOTH THE FO AND I DONNED OUR OXYGEN MASKS IMMEDIATELY. THE INTENSITY OF THE SMOKE WAS INCREASING. I DISCONNECTED THE AUTOPLT AND AUTOTHROTTLES AND TURNED BACK TOWARDS PBI. THE FO HAD TROUBLE ESTABLISHING CONTACT WITH ATC. I WAS ABLE TO COMMUNICATE WITH ZMA AND DEMAND A RETURN TO THE NEAREST ARPT. I INITIALLY REQUESTED DIRECT FLL THEN REALIZED PBI WAS CLOSER AND WAS CLRED DIRECT PBI. THE FO STARTED THE CHKLIST FOR INTERIOR FIRE/SMOKE. THE L1 FLT ATTENDANT THEN ENTERED THE COCKPIT TO TELL US ABOUT THE 'MIST' IN THE CABIN. I TOLD HER WE WERE RETURNING TO PBI. I WAS DSNDING AT APPROX 335 KIAS DIRECT THE PBI VOR. I THEN MADE A QUICK PA TO PAX. WE CONTACTED PBI APCH CTL AND CLRED FOR THE VISUAL RWY 27R. AT THIS TIME THE SMOKE WAS GONE AND THE FO AND I REMOVED OUR OXYGEN MASKS. I INFORMED ATC THE SMOKE WAS NOW GONE; BUT REQUESTED THE EMER EQUIP WOULD MEET US. THE FO AND I COMPLETED THE DSCNT/APCH AND LNDG CHKLISTS AND MADE A NORMAL LNDG. OUR LNDG WT WAS APPROX 13500 LBS (MAKING US OVERWT). AFTER SPEAKING WITH THE TWR CTLR AND DIRECTLY TO THE FIRE TRUCKS; I WAS ASSURED THERE WAS NO FIRE OR SMOKE IN OR AROUND THE ACFT. I MADE A BRIEF PA TO THE PAX AND THEN TAXIED TO THE GATE AND THE PAX DEPLANED THROUGH THE JETWAY. NO DAMAGE TO THE ACFT AND NO INJURIES TO PAX. THE CAUSE OF THE SMOKE WAS DETERMINED TO BE AN OIL LEAK IN THE APU ALLOWING A SMALL AMOUNT OF OIL INTO THE AIR CONDITIONING SYS. THE PROB WAS FIXED; AN OVERWT LNDG INSPECTION COMPLETED AND ALTHOUGH 4 HRS LATE; WE COMPLETED THE FLT TO LGA.