TONIGHT'S MUST-SEE

"Nova: The Deadliest Plane Crash," 8 p.m., PBS. Tenerife, one of the Canary Islands, has less than a million people. It also has two airports and a footnote in aviation history: Two 747 jumbo jets crashed there in 1977, killing 583 people. It's listed as the deadliest plane accident ever. That happened because of a worst-case confluence: a bomb threat at a bigger airport, thick fog, verbal misunderstandings and a fatal error. This documentary makes rich use of re-enactments, plus memories of survivors. They include a co-pilot, a flight attendant, some passengers and a woman who got off the plane. There are also looks at what has and hasn't changed. One key change: Crew members are encouraged to second-guess the pilot.

OF NOTE

"Dancing With the Stars," 7 p.m., ABC. The sixth week begins.

"Friday Night Lights," 7 p.m., NBC. With the star quarterback partially paralyzed and the team struggling, the entire town seems upset. Now the coach and the reserve quarterback are under fire; there's even talk about bending the rules to lure an out-of-town quarterback.

"NCIS," 7 p.m., CBS. Someone has dug up a missing Marine and placed the body in a house.

"Man, Moment, Machine," 7 p.m., History Channel. When the Apollo 13 crew was stranded in space in 1970, the solutions required human innovation. Jim Lovell, the flight commander, did his figuring by pencil. Back at Flight Control, people re-checked his math, also by pencil. There were makeshift approaches that worked. An involving story is retold here, including new interviews with the key people.

"The Unit," 8 p.m., CBS. An African dictator is in the U.S. for surgery. Now the team has the difficult job of returning him to his homeland safely.

"Law & Order: Criminal Intent," 8 p.m., NBC. Two brothers, seemingly opposites, have been killed.