Tonight it's pretty much a tie between network and cable TV -- there are only a few decent things offered on either one. On the networks, rely on "Northern Exposure" and check out a new NBC television movie. On cable, old movies are your best shot.
* "The Day My Parents Ran Away" (8-10 p.m., WBFF, Channel 45) -- In an older, but not necessarily wiser, version of "Home Alone," a teen-ager (Bobby Jacoby) is left alone during the holidays by his parents -- but this time the act was intentional. Blair Brown and Matt Frewer star as the parents eager to escape, and it's a good bet that acting duo wanted to escape from this Fox television movie as well. Also starring: Martin Mull. Fox.
* "Mercy Mission: the Rescue of Flight 771" (9-11 p.m., WMAR, Channel 2) -- It's a normal reaction to veer away from any docudrama with a flight number in its title, but stick around for this one. Scott Bakula and Robert Loggia star as pilots in this fact-based incident. The touching, very exciting drama is about a race against time (and a depleting fuel supply) to help a lost pilot get his bearings, or to find him, before he plunges into the Pacific. NBC.
* "Murphy Brown" (9-9:30 p.m., WBAL, Channel 11) -- For the first time in the history of "Murphy Brown," the secretary gets a letter as well as a number: Tonight's episode makes room for secretaries 64A and 64B, played, respectively, by James and Jeffrey Thiel. CBS.
* "Northern Exposure" (10-11 p.m., WBAL, Channel 11) -- Lots of other weekly series take great pains to note the passage of Halloween, Thanksgiving and Christmas, but only "Northern Exposure" builds an annual special episode out of the winter's first snowfall. Maybe it's because this show is just a little flakier than all the others. CBS.
* "The Untold West" (8:05-9:05 p.m., TBS) -- I could tell you what this documentary is doing tonight, but then they'd have to change the title.
* "It's a Wonderful Life" (9-11:45 p.m., TNT) -- This year, because of new copyright filings, this movie no longer resides in the public domain, so you'll get a chance to see it only three times on TV this holiday season -- and sometimes colorized. That's why tonight's black-and-white showing, once again, is a special event.
* "The Comic" (11:45 p.m.-1:45 a.m., TNT) -- Two movies featuring Dick Van Dyke are shown tonight. This rarely seen 1969 movie, a sort of silent-movie variation of "Days of Wine and Roses," gets strong performances from Van Dyke and Michele Lee . . .
* "Bye Bye Birdie" (1:45-4:05 a.m., TNT) -- . . . While this chirpy 1963 film musical also makes good use of a young and vibrant Ann-Margret.