The Massachusetts Board of Education has approved plans to give four failing schools more latitude to devise their own strategies to improve. The schools have been facing state intervention after years of dismal performance on statewide tests. But the state has had little success with the remedial plans it has imposed on failing schools so it has decided to give the schools more autonomy by turning them into "pilot schools". Pilot schools, like charters, have more freedom than traditional public schools. They can set longer school days, choose their staffs, and determine how they spend their budgets, but are overseen by the school system.