As Captain Airwaves has noted so often in the past: When you're hot, you're hot . . .

And NBC -- with the exception of daytime programming -- is fairly simmering these days . . . first in primetime, early morning and late night . . .

Just last week, "NBC Nightly News With Tom Brokaw" came within 91,000 TV homes of catching the perennial network news champion, "CBS Evening News With Dan Rather," in the weekly ratings . . .

For the week, CBS had a 13.3 Nielsen rating (representing 11.4 million TV homes) and a 23 percent audience share, compared with NBC's 13.2/23 (11.3 million) and "ABC World News Tonight's" 12.7/22 (10.9 million) . . .

That's the closest NBC has been to numero uno in ratings since the two shows tied the week of Feb. 26, 1982, and the first time they've tied in audience share since a week in April 1982 . . .

"CBS Evening News" is due to celebrate its 200th straight week at the top of the ratings this week. Maybe . . .

But before you run out and sell your CBS stock this morning CBS News Executive Vice President Howard Stringer cautions that "it was a holiday week, which traditionally shows aberrations in the ratings for us. Just remember that the more the sun comes out each spring, the better CBS will do" . . .

He acknowledged that NBC has improved its audience numbers while "we've held steady" but expressed no concern over last week . . .

At NBC News, Vice President Tim Russert, whose arrival at the network 16 months ago presaged a big boost in on-air promotion for the division, said yesterday that he felt Brokaw's recent success is partly due to his performance the afternoon of the shuttle tragedy . . . and because of a new energy on all NBC news programs, including "Today" and "Meet the Press" . . .

"The promotion isn't all that important," Russert insisted yesterday. "I think the News division is just a lot more aggressive and the public is becoming aware of it" . . .

Even ABC found something to crow about in the latest news figures . . . "World News Tonight" was up 17 percent from the same week a year ago, while NBC was up 13 percent and CBS was down 1 percent, while only six-tenths of a Nielsen point separated the three news shows the week ending Feb. 21 . . .

Speaking of Brokaw, he taped a 3 p.m. news interrupt in Washington yesterday, but somebody made a mistake in the New York control room and instead of the news tape, viewers saw Brokaw sitting at a desk, combing his hair for 30 seconds . . .

Well, as Captain Airwaves always says: When you're not, you're not . . .

Also in the NewsChannel 4 announced yesterday that reporter Kelly Burke has signed a new long-term contract and is returning to the air as a general assignment reporter . . .

Burke was injured in a traffic accident in July 1984 that claimed the life of the driver of the other car involved in the crash . . .

He has been working as a field producer for the station since . . .

The conclusion of "Blood & Orchids" on CBS Monday night registered a strong 25.6 national Nielsen rating and a 38 percent audience share . . .

Meanwhile, "Annie" on NBC had a 19.3/28 while Part II of "Crossings" on ABC slipped to a 15.0/22 . . .

NBC News is considering another trip for its peripatetic "Today" show crew . . . this time Down Under to Australia next January for the America's Cup (actually, Australia's Cup) yacht races . . .

Channel 9 has hired Diane Digit to be manager of press relations . . . starting March 10. She comes from WABC-TV, the ABC-owned station in New York, where she was assistant press person . . .

The job has been open for three months, since Deb Baker-Hall left on maternity leave. Baker-Hall will have a new assignment when she returns . . .

And Channel 4 has signed Lou Charlip as a sports producer. He's most recently been an editor/producer on Baseball News Satellite in New York . . .

Also at Four, Bob Casazza, who has been director of advertising and promotion at the station since 1979, is leaving to start his own full-service agency here, to be called Casazza Advertising . . .

He first broke into this market in 1971 at Channel 9 and in 1977 helped create that station's very successful "The One and Only" promotion campaign . . .

After two years with WMAQ, the NBC-owned station in Chicago, Casazza came to WRC, where a few years ago he helped create "The Team 4 News" campaign . . .

Casazza expects to leave the station sometime after mid-March. No replacement has been named . . .

TV Ratings

CBS and ABC had the movies but NBC's solid series lineup carried the week again . . . as the season front-runners averaged a 17.5 Nielsen rating and a 27 percent audience share, compared with CBS' 17.1/26 and ABC's 15.4/24 . . .

The win for the week ending Feb. 23 virtually cinched the February ratings sweeps for NBC . . .

Running down the rankings, ABC's "Choices" finished 23rd for the week, NBC's "Flashdance" was 24th and Part I of ABC's "Crossings" was 26th . . .

"The Academy of Country Music's 20th Anniversary Reunion" on NBC was 37th while "The Disney Sunday Movie" on ABC was 44th . . .

NBC's egregious "The Fifth Missile" was 46th, while CBS' "Welcome Home, Bobby" was 55th . . .

Occupying the Final and All Things Considered the Usually Fatal Five were, in order, five ABC offerings, including "Fortune Dane," in 64th, followed by "The Redd Foxx Show," "Benson," "The Fall Guy," and "Ripley's Believe It or Not!" in 68th and last place . . .