B757 FA NOTICES THAT DOORS 1L AND R HAVE NOT BEEN ARMED AS THE ACFT TAKES THE RWY FOR DEPARTURE AND ARMS THEM.

Narrative

WHILE ACTING AS PURSER ON A B757 ACFT WITH A TOTAL OF 4 FLT ATTENDANTS; THE FLT WAS FULL AND BOARDING WAS VERY RUSHED. I MANAGED TO GET THE PREDEPS DONE AND COORD A FEW BAG ISSUES FOR WHICH THE CSR'S HAD TO START CHKING BAGS. I CONFIRMED WITH BOTH MR X AND MS Y THAT THE EXIT ROWS HAD BEEN BRIEFED PRIOR TO THE DOOR'S CLOSING. WHILE THE CSR CLOSED DOOR 2L; I WAITED. WHEN THE JETWAY WAS PULLED I ANNOUNCED FOR THE FLT ATTENDANTS TO ARM DOORS FOR DEP. WE PUSHED BACK SHORTLY AFTER XA09. I BECAME DISTR BY CUSTOMER REQUESTS AS I MADE MY WAY TO DOOR 1. I MADE MY WAY UP AND LET THE PLTS KNOW THAT THE CABIN WAS SECURE. THEY ACKNOWLEDGED ME AND I CLOSED THE COCKPIT DOOR. WE PERFORMED THE SAFETY DEMO AND CONDUCTED OUR SAFETY CHKS. I SAT IN MY JUMPSEAT. THE CAPT ANNOUNCED 'FLT ATTENDANTS PREPARE FOR TKOF.' APPROX 30 SECONDS PRIOR TO BEGINNING THE TKOF ROLL; I NOTICED THAT I HAD NOT ARMED DOORS 1L AND 1R. WHY? I WAS DISTR FROM MY SAFETY DUTIES WITH CUSTOMER REQUESTS (NOTING I WALKED PAST 24 PAX AS I MADE MY WAY UP TO DOOR 1). WHAT ACTION WAS TAKEN? I QUICKLY ARMED 1L AND 1R AND RETURNED TO MY JUMPSEAT. WHAT WAS THE OUTCOME? WE TOOK OFF AND COMPLETED THE FLT AS NORMAL. ADDITIONAL INFO: IN THE PAST; I HAVE BEEN PURSER ON A B757 'UNDERSTAFFED' TO 4 FLT ATTENDANTS.