A DH8 FLC OVERSHOOTS THEIR ASSIGNED ALT DURING A TURN AND POTENTIAL CONFLICT WITH TFC JUST S OF HPN; NY.

Narrative

I WAS FLYING A TRIP FROM HPN; NY; TO PHL; PA. IT WAS MY VERY FIRST TRIP AFTER COMPLETION OF SOE (IOE). THE WX ALL DAY HAD BEEN VERY TURB; GUSTY; RAIN/SNOW; WINDSHEAR AND IMC. THE CAPT; BEING FROM A FOREIGN COUNTRY; WAS NOT ALWAYS EASY TO UNDERSTAND AND SEVERAL TIMES THROUGHOUT THE DAY; I HAD TO ASK HIM TO REPEAT HIMSELF OR I HAD TO CLARIFY WHAT I SAID BECAUSE HE DID NOT UNDERSTAND. AFTER I RECEIVED OUR CLRNC AND READ IT TO HIM; I SET 2000 FT IN THE ALT SELECT WINDOW. OUR CLRNC WAS THE WESTCHESTER 9 DEP (SID) OFF RWY 16 -- ADJUSTED TO 2000 FT. WE WERE CLRED FOR TKOF. I CONFIRMED THAT HE WANTED ME TO FLY THIS LEG OF THE TRIP. WE STARTED A TURN TO 320 DEGS (R TURN). AS WE TURNED; WE ENTERED VISUAL CONDITIONS (APPROX 3 MI VISIBILITY; LIGHT SNOW). AT THAT POINT; I SAW LNDG LIGHTS AHEAD AND TO OUR R APPROX 3 MI. AT THE SAME TIME WE HAD A TCASII ALERT. I QUICKLY REDUCED CLB AND TURN AND AFTER THAT; I POINTED TO THE TFC AND SAID 'THERE HE IS; 1 O'CLOCK POS.' AT THAT POINT WE HAD ANOTHER TCASII ALERT. IMMEDIATELY THE CAPT TOOK THE CTLS; TURNED L APPROX 30 DEG BANK; AND STARTED TO PUSH FORWARD ON THE YOKE. AT THAT POINT WE RECEIVED A 'STOP CLB' MESSAGE. THAT WAS SURPRISING BECAUSE I HAD JUST NOTICED HOW FAR FORWARD THE YOKE LOOKED. I COULD TELL THAT THE TFC WOULD PASS CLR OF US (OFF THE R). THEN THE CAPT SAID 'WE'RE IN AN UPDRAFT.' THIS WAS SAID AT THE SAME TIME I SAW THE TFC PASS BY. I THEN LOOKED AT THE VSI AND NOTICED THE NEEDLE BOUNCE FROM ZERO TO APPROX 500 FPM. I THEN GRABBED THE PWR LEVERS AND REDUCED ENG TORQUE. THE VSI NEEDLE WAS STILL ERRATIC; BUT WE WERE DSNDING AT THIS POINT. WE THEN LEVELED OFF AND THEN THE CAPT ASKED ATC WHAT AN ACFT WAS DOING IN THE DEP AREA AND I BELIEVE ALSO WHY WE WERE ASSIGNED TO TURN TO 320 DEGS. ATC SAID THEY DIDN'T KNOW; BUT A SUPVR WOULD LOOK INTO IT AND GAVE US A TELEPHONE NUMBER TO CALL. THE CAPT SAID 'NO;' AND THEN SAID TO ME 'WE WERE ASSIGNED XXX. I DON'T KNOW WHAT HAPPENED; WHY HE WAS THERE -- SEE WHITE PLAINS YOU HAVE TO BE VERY CAREFUL THERE; LOTS OF TFC.' IN CONCLUSION; I THINK SEVERAL THINGS CAUSED THIS TO HAPPEN. FIRST; ATC ISSUED A SID; BUT MADE MODIFICATIONS TO IT. IF THEY WANTED US TO FLY TO 2000 FT AND THEN TURN ON RWY HDG; THEN THAT SHOULD HAVE BEEN THE CLRNC. THEY SHOULDN'T ISSUE PART OF A SID. SECOND; I BELIEVE; EVEN THOUGH I READ THE CAPT THE CLRNC; I THINK HE'S FLOWN IN AND OUT OF THERE SO MANY TIMES THAT WHEN HE HEARD 'XXX;' HE DIDN'T PAY ATTN TO THE CHANGES. I ASSUME HE CHANGED THE ALT SELECT WINDOW TO 3000 FT; AS THE SID CALLS FOR; BELIEVING THAT I PUT IN THE WRONG ALT; SINCE I AM BRAND NEW. I NEVER REALIZED IT HAD BEEN CHANGED SINCE IT DIDN'T SEEM ODD TO ME; AND ONCE IT IS SET; THERE IS NO REASON TO REST IT OR RECHK IT. I WAS HEADS DOWN IN THE MANUAL. THE CAPT HAD TO BE VERY CAREFUL TAXIING BECAUSE OF SNOW ON THE RAMP AND BEING DARK OUT. WE WERE LATE BECAUSE OF WX; SO OF COURSE WE WANTED TO GET ON OUR WAY. I DON'T KNOW WHAT ALT WE REACHED. I WOULD GUESS ABOUT 2500 FT; DUE PARTLY TO THE WRONG ALT EXPECTED AND UPDRAFTS. BUT EVEN IF WE LEVELED OFF AT 2000 FT; AND THEN TURNED AS THE SID INSTRUCTS; IT MAY HAVE ENDED UP BEING A CLOSER CONFLICT BECAUSE WE WOULD HAVE FLOWN RIGHT UNDER OUR TFC; WHICH WOULD HAVE BEEN DANGEROUS WITH THE GUSTY WINDS; TURB; UP-AND DOWNDRAFTS AND WINDSHEAR. I BELIEVE ATC SHOULD HAVE WAITED TO GIVE US TKOF CLRNC; AND ALSO IT DID NOT HELP THAT I WAS BRAND NEW. FIRST DAY ON THE JOB AND NEVER FLOWN INTO WHITE PLAINS BEFORE.