Air Crash Investigations, 8.30pm, Seven ( Sydney and Brisbane only) The Boeing 737 is one of the most popular passenger jets in the world. It has carried more than 12 billion people around the globe. But in 1991, something happened on a 737 travelling from Denver to Colorado Springs that sent shudders through the aviation world. The plane suddenly rolled then spiralled out of control, smashing into the ground and killing all on board. It took 10 years, the longest crash investigation in aviation history, to understand what happened. Cold Case, 8.30pm, Nine January, 1996: a man reflects with his family on a recent trip to Rwanda. His estranged mother turns up unexpectedly and, following a massive power cut and some powerful bitching in the dark, she is found floating face down in the family swimming pool next morning. Jump to the present. When the house is sold for the first time, scratch marks are found under the diving board. Enter Detective Rush ( Kathryn Morris, pictured). The Unteachables, 9.30pm, UKTV Some 140,000 children are expelled from British schools each year. Is the system to blame or are these kids simply unteachable? A man in a field in Suffolk is behaving oddly. But he’s got 16 troublesome teenagers eating out of his hand. What is his secret? Imagine 16 foul- mouthed Vicky Pollards in the same class ( or field) and you begin to get a sense of what this is all about. Education revolution, or expensive indulgence?