WASHINGTON—The Federal Aviation Administration said on Thursday it has tapped a Canadian airline safety official to head the agency’s aviation safety organization. Billy Nolen, who has most recently been vice president for safety, security, and quality for WestJet Airlines in Canada, will begin early next year as the FAA’s associate administrator for aviation safety, leading a team of more than 7,600 FAA employees. The FAA’s safety efforts and oversight of Boeing have come under criticism after two fatal 737 MAX crashes in a five-month period between October 2018 and March 2019 that killed 346 people. In December last year, Congress passed legislation to reform how the FAA certifies new airplanes and to reduce how much it delegates some duties to manufacturers like Boeing. Nolen will replace Ali Bahrami, who stepped down in June after facing harsh criticism from relatives of the two fatal 737 MAX crashes and some lawmakers. Nolen …