CLRNC INTERP; TCASII RA RESULT IN ALTDEV.

Narrative

WHILE LEVEL AT FL230; 10 DME W OF STW VOR; FLT ATTENDANT ENTERED THE COCKPIT TO DISCUSS A CABIN PROB. AS SHE WAS TALKING; THE FE WAS BUSY MONITORING ATIS FOR THE JFK ARR. AT THE SAME TIME; ATC ISSUED A CLRNC. FO UNDERSTOOD THE CLRNC TO BE CROSS LENDY INTXN AT 15000 FT AND 250 KTS. HE THEN SET 15000 FT IN THE ALT REMINDER. CAPT POINTED TO THE SETTING AND SAID; 'CLRED TO CROSS LENDY AT 15000 FT AND 250 KTS; CORRECT?' FO ACKNOWLEDGED. THIS XING WOULD HAVE 'FELT' NORMAL BASED ON OUR USUAL PLANNED DSCNTS OF 3:1 DISTANCE TO ALT RATIO WITH ROOM TO SLOW TO 250 KTS. AT THE SAME TIME; THE AUTOPLT WHICH HAD PREVIOUS WRITEUPS BUT HAD BEEN SIGNED OFF; GAVE A SERIES OF 3 JOLTS IN THE PITCH MODE. THE AUTOPLT WAS DISCONNECTED DURING THE FO'S READBACK AND THE VERIFICATION PROCESS. THERE WERE NO FURTHER XMISSIONS RECEIVED FROM ATC. IN THE DSCNT; SPURIOUS ELECTRIC SIGNALS CAUSED PROBS WITH THE AUTOPLT; AUTO THROTTLES; AND THRUST RATING INDICATOR. DSNDING THROUGH 15500 FT; TCASII GAVE 'TFC' WITH POPUP TFC AT 12:30 POS SHOWING 600 FT BELOW OUR ALT. DSCNT WAS SHALLOWED FOLLOWED BY VISUAL CONTACT AT 1-2 O'CLOCK POS. TCASII THEN GAVE 'DSND' MESSAGE. DSCNT WAS INCREASED TO COMPLY. TFC WAS MOVING TO 3 O'CLOCK AT THIS TIME. AT THE SAME TIME WE RECEIVED 'CLR OF TFC' MESSAGE. ATC CALLED FOR THE FIRST TIME DURING THE DSCNT AND SAID WE HAD BEEN CLRED TO 19000 FT AND RPTED OUR TFC AT APPROX 3 O'CLOCK. CLB WAS INITIATED VISUALLY DUE TO CONTINUING AUTOPLT AND AUTO THROTTLE SYS PROB. AT 17000 FT; ATC RECLRED US TO 16000 FT AND GAVE A CHANGE OF FREQ. PROPER PHRASEOLOGY MAY HAVE BEEN A CONTRIBUTING FACTOR. ADDITIONALLY; PREVIOUS COMMENTS HAD BEEN MADE AS TO THE RECEPTION QUALITY OF ATC COMS. SOME OF THE PREVIOUS COMS HAD BEEN SOMEWHAT DIFFICULT TO UNDERSTAND.