SHORT 1 CAB DUE TO EQUIP CHANGE.

Narrative

THE FLT WAS FLOWN FROM IAD TO MSP WITH 2 FLT ATTENDANTS (FA'S) WHEN 3 ARE REQUIRED FOR THE AIRPLANE. SEVERAL FACTORS LED TO THIS OCCURRENCE. FIRST; THE ORIGINAL EQUIP SCHEDULED FOR THE FLT; AN MLG REQUIRED ONLY 2 FA'S; BUT WHEN THE ACFT ARRIVED; AN EQUIP SUBSTITUTION HAD BEEN MADE TO AN MLG B. ORIGINALLY A 100 SEAT AIRPLANE; IT HAD BEEN RECONFIGURED TO HOLD 112 PASSENGERS. WE HAVE VERY FEW MLG B AND FLY ONE MAYBE ONCE EVERY MONTH. THE COCKPIT IN THIS WAS NO DIFFERENT THAN A AND GAVE LITTLE CLUE THAT AN EQUIP SUBSTITUTION HAD BEEN MADE. ANOTHER FACTOR WAS THE COMPANY'S PROC OF PROVIDING EXTRA FLT ATTENDANTS ON CERTAIN FLTS. A COMMON CREW OF 2 FLT ATTENDANTS IS NORMAL WITH ADDITIONAL FA'S SHOWING UP DURING THE DAY AS MEAL SVC ON ACFT REQUIREMENTS OR FA POSITIONING REQUIREMENTS DICTATE. AN EXTRA FA SHOULD HAVE BEEN ON THE ACFT WHEN IT ARRIVED. ANOTHER FACTOR WAS THE LATE OP OF THE FLT. A QUICK TURN AROUND OF THE ACFT KEPT US ALL VERY BUSY TRYING TO GET READY TO GO; WITH LITTLE TIME FOR CONTEMPLATING THE NEED FOR AN EXTRA FA; OR FOR REALIZING THAT AN EXTRA HAD NOT ARRIVED WITH THE ACFT. (THEY SOMETIMES DISAPPEAR FOR A WHILE TO SMOKE; MAKE PHONE CALLS; EAT A SNACK; USE RESTROOM; ETC). ANOTHER FACTOR; AND MAYBE THE MOST IMPORTANT FOR THE COCKPIT CREW; WAS THE MSP WX. WE WERE HEADED BACK TO THE WORST SNOW STORM IN MSP HISTORY. HAVING OPERATED THROUGH THERE THE PREVIOUS DAY (THE FIRST DAY OF THE STORM); I WAS VERY MUCH PREOCCUPIED WITH VISIONS OF THE PREVIOUS DAYS EXCITING APCH AND LNDG. OUR FINAL PAPERWORK SHOWED 3 FA'S ON BOARD; AND THE COPLT LATER STATED THAT HE THOUGHT THAT WE HAD 3; BUT THAT THE EXTRA HAD NOT HAD TIME TO MAKE IT TO THE COCKPIT TO SAY HELLO. THE LEAD FLT ATTENDANT OF OUR CREW SHOULD HAVE PROTESTED LOUD AND LONG ABOUT BEING SHORT CREW; BUT BOTH FA'S FAILED TO ADJUST TO THE EQUIP CHANGE; AND WITH ONLY 44 PASSENGERS ON BOARD; NO EMER BELLS WERE RINGING IN THEIR HEADS. CREW SCHEDULING AND/OR THE CREW COORDINATOR PLAYED THEIR PART IN NOT SCHEDULING AN EXTRA FOR US; BUT AGAIN; THE STORM IN MSP HAD TIME IN NEAR PANIC TRYING TO KEEP UP WITH NO-SHOWS; CANCELLATIONS; AND DIVERSIONS. THE MISTAKE WAS NOT CAUGHT UNTIL WE ARRIVED IN MSP AND TRIED TO FIND OUT THIRD FA SO THAT WE COULD CONTINUE THE NEXT LEG. ANOTHER LESSON LEARNED THE HARD WAY!