ACR MLG FLC EXPERIENCES ALT OVERSHOOT (AND POSSIBLE CONFLICT WITH TFC Y) ON DEP FROM PHL DUE THEIR HAVING INCORRECTLY SET THE ALTIMETER.

Narrative

IT WAS THE CAPT'S LEG FROM PHL TO ATL. WE WERE DEPARTING AND CLRED TO 10000 FT. ATC TOLD US OF TFC Y AT 10 TO 11 O'CLOCK AT 11000 FT. WE TOLD HIM HE WAS IN SIGHT. I ASKED THE CTLR WHAT HIS ALT WAS SUPPOSED TO BE AGAIN BECAUSE I THOUGHT HE LOOKED LOWER THAN 1000 FT ABOVE US. THE CTLR CONFIRMED HE WAS AT 11000 FT; THEN ASKED US TO VERIFY OUR ALT; I TOLD HIM WE WERE AT 9700 FT LEVELING AT 10000 FT. HE SAID OUR ALT SHOWED 10700 FT. I ASKED FOR THE CURRENT ALTIMETER SETTING. HE SAID 30.72 WE BOTH (CAPT AND FO AND ALT WARNING) HAD 29.72 SET. BACK TO THE PREVIOUS LEG FROM ATL TO PHL; IT WAS MY LEG (FO) AND AS WE WERE DSNDING OUT OF 18000 I BELIEVE THE CTLR GAVE US THE WRONG ALT SETTING OF 29.69. AS WE DSNDED WE NEVER LEVELED OFF AT ANY OF OUR ALTS. THEN WE WERE CLRED FOR THE VISUAL APCH SO WE NEVER REALIZED WE WERE AT THE WRONG ALT OR HAD THE WRONG SETTING. WE LANDED AND TAXIED TO THE GATE. AS WE WERE PREPARING FOR DEP BACK TO ATL; I GOT THE DEP ATIS AND ON IT IT SAID THE ALTIMETER WAS 30.72. NOW REMEMBER IN THE ALT REMINDER WE HAD 29.69 SET SO I REACHED DOWN AND CHANGED THE SETTING FROM .69 TO .72 AND DIDN'T REALIZE WE WERE OFF BY 1000 FT.