ToplineA schoolteacher in Oregon has found a “key missing component” from the Alaska Airlines jet that blew open mid-flight last week, the National Transportation Safety Board (NTSB) announced Sunday, an important step towards understanding what happened as U.S. airlines ground dozens of aircraft over safety concerns.An Alaska Airlines Boeing 737 MAX 9 plane sits at a gate at Seattle-Tacoma International Airport in ... [+] Seattle, Washington.Getty Images Key FactsA Portland schoolteacher has found the miss ...