The complete original broadcast, up until Chuck Howley's second interception, the first play of the fourth quarter exists, however the rest of the fourth quarter is missing from network vaults. Broadcast excerpts of the crucial fourth-quarter plays, recovered from the Canadian feed of NBC's original, do exist and circulate among collectors. (Two different NFL Films game compilations also cover the fourth quarter plays, in part.) By 1971, the Federal Communications Commission (FCC) introduced the Prime Time Access Rule, which freed local network affiliates in the top 50 markets (in practice, the entire network) to take a half-hour of prime time from the networks on Mondays through Saturdays and one full hour on Sundays. Because nearly all affiliates found production costs for the FCC's intended goal of increased public affairs programming very high and the ratings (and by association, advertising revenues) low, making it mostly unprofitable, the FCC created an exception for network-authored news and public affairs. After a six-month hiatus in late 1971, CBS would find a prime place for "60 Minutes" in a portion of that displaced time, 6:00 to 7:00 p.m. (Eastern; 5:00 to 6:00 Central Time) on Sundays, in January 1972. This proved somewhat less than satisfactory, however, because in order to accommodate CBS' telecasts of late afternoon National Football League games, "60 Minutes" went on hiatus during the fall from 1972 to 1975 (and the summer of 1972). This took place because football telecasts were protected contractually from interruptions in the wake of the infamous "Heidi Game" incident on NBC in November 1968. Due largely to CBS' live broadcast of NFL games, as well as other sports events aired by the network that run past their scheduled end time, "60 Minutes" sometimes does not start until after 7:00 p.m. Eastern Time, with the program starting right after the conclusion of game coverage (however, on the West Coast, because the actual end of the live games is much earlier in the afternoon in comparison to the Eastern and Central Time Zones, "60 Minutes" is always able to start at its normal 7:00 p.m. Pacific start time, leaving affiliates free to broadcast local newscasts, the "CBS Evening News", and other local or syndicated programming leading up to "60 Minutes"). The program's success has also led CBS Sports to schedule events leading into "60 Minutes" and the rest of the network's primetime lineup, causing (again, except on the West Coast) the pre-emptions of the Sunday editions of the "CBS Evening News" and affiliates' local newscasts.