A B747-400 captain reported that he may have exceeded the rest requirement per the far.

Attributes
ACN	588476
Time
Date	200306
Day	Tue
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B747-400
Operating Under FAR Part	Part 121
Flight Phase	ground : parked
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 200 flight time total : 12000 flight time type : 1800
ASRS Report	588476
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	non adherence : company policies non adherence : far non adherence : published procedure
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	other
Supplementary
Problem Areas	Company Flight Crew Human Performance
Primary Problem	Ambiguous

Narrative:

The event is a potential exceedance of far 121 flight times. Specifically, exceeding 32 hours in 7 days (int'l operations). We flew the pairing as published. It was scheduled for 35 hours 14 mins from jun/tue, XA05Z through jul/tue by starting jun/mon, XB01Z, resulted in a scheduled time of 34 hours 19 min. One actual block time for the same period was 33 hours 37 mins. Both exceeded 32 hours in 7 days. However, if the entire flight time for the leg which began on the tue (5 hours 45 mins scheduled, 5 hours 48 mins actual) is counted only against the tue, not part (+55/+52 mins) against the tue and the balance against the wed, then the block times are 29+29 scheduled and 28+41 flown. No violation occurs. It becomes a question on how the time is counted.

Original NASA ASRS Text

Title: A B747-400 CAPT RPTED THAT HE MAY HAVE EXCEEDED THE REST REQUIREMENT PER THE FAR.

Narrative: THE EVENT IS A POTENTIAL EXCEEDANCE OF FAR 121 FLT TIMES. SPECIFICALLY, EXCEEDING 32 HRS IN 7 DAYS (INT'L OPS). WE FLEW THE PAIRING AS PUBLISHED. IT WAS SCHEDULED FOR 35 HRS 14 MINS FROM JUN/TUE, XA05Z THROUGH JUL/TUE BY STARTING JUN/MON, XB01Z, RESULTED IN A SCHEDULED TIME OF 34 HRS 19 MIN. ONE ACTUAL BLOCK TIME FOR THE SAME PERIOD WAS 33 HRS 37 MINS. BOTH EXCEEDED 32 HRS IN 7 DAYS. HOWEVER, IF THE ENTIRE FLT TIME FOR THE LEG WHICH BEGAN ON THE TUE (5 HRS 45 MINS SCHEDULED, 5 HRS 48 MINS ACTUAL) IS COUNTED ONLY AGAINST THE TUE, NOT PART (+55/+52 MINS) AGAINST THE TUE AND THE BAL AGAINST THE WED, THEN THE BLOCK TIMES ARE 29+29 SCHEDULED AND 28+41 FLOWN. NO VIOLATION OCCURS. IT BECOMES A QUESTION ON HOW THE TIME IS COUNTED.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.