The　scientific　positioning　of　fire　detectors,　and　their　technical　parameters,　requires　an　understanding　of　how　the　maximum　temperature　of　the　flame　ceiling-jet　is　distributed.　Experiments　with　small　scale　models(1:8)　and　numerical　simulations　were　used　to　determine　the　maximum　temperature　of　the　flame　above　the　fire　source　and　how　the　ceiling　jet　was　distributed　along　the　length　of　the　tunnel.　The　Alpert　formula　customarily　used　is　only　appropriate　for　estimation　of　the　maximum　temperature　of　pure　smoke　ceiling　jets　but　not　flame　ceiling　jets.　As　the　distance　from　the　fire　center　line　increases,　the　maximum　temperature　of　the　flame　ceiling　jet　gradually　decreases.　The　decrease　is　linear　along　the　tunnel　longitudinal　direction　where　the　flame　has　an　impact.　Away　from　the　impact　of　the　flame,　the　decrease　in　maximum　temperature　follows　a　power　function.　A　new,　revised　Alpert　formula　is　developed　to　estimate　the　maximum　temperature　of　a　flame　ceiling　jet.