The sad secret of broadcast news ratings is what’s on before you. Many’s the night we’d pat ourselves on the back for a ratings win over our rivals when the battle had been won by John Thaw and his dark red Jag in Inspector Morse.

In the U.S. two network news shows have just changed Executive Producers – NBC and CBS. NBC is losing viewers and CBS doesn’t have enough of them to go round.

The New York Times dissects their problems:

In almost every market, the immediate lead-in is a half-hour of local news. Even in an age where viewers can, with the mere touch of a remote control, choose from among hundreds of channels, most continue to get their network news from the same station that provides their local news…

In many major markets, local newscasts on CBS stations have languished in third place for well over a decade, despite expensive attempts to prop them up with lead-ins like Judge Judy. Those struggles, in turn, have affected viewership for the network newscast.

“In order to get someone to switch to the Evening News With Katie Couric,” said David F. Poltrack, chief research officer for the network, “essentially they’re going to have to switch off from the local news on another channel, or switch their entire viewing from another channel to CBS.”

And Katie Couric is shedding viewers from her small lead-in inheritance. Things are glum too for the NBC Nightly News and its anchor Brian Williams, they’re gaining viewers, but not as many as the local newscasts are losing:

According to a NBC analysis of the Nielsen ratings in the seven largest markets where it owns stations, Mr. Williams has actually increased the number of viewers he has been able to add to the audience delivered to him by the local newscasts in those markets, when this television season is compared with last year. This year, Nightly News has added, on average, 190,000 viewers to its lead-in audience in those cities, when compared to a gain of 130,000 over its lead-in a year ago.

But over that same period, the audience fed to Mr. Williams’s program has been shrinking; since last year, the combined, half-hour lead-in to Mr. Williams’s program in those markets has dropped by 225,000 viewers, to 1.2 million. Because the lead-in audience has fallen so precipitously, Mr. Williams has wound up losing ground overall.

Still NBC is on the case, and beefing up its major market local newscasts, for example in New York.

As possibly my favourite movie quote of all time (from Aliens) puts it: “We’re on an express elevator to hell – going down!”