SALT LAKE CITY (KTVX) — The Federal Aviation Administration (FAA) is launching an investigation into the Delta Airlines flight that was diverted back to Salt Lake City International Airport shortly after takeoff due to a pressurization issue. The flight was bound for Portland on Sunday, Sept. 15, when it was forced to divert back just 15 minutes after takeoff. Delta Airlines said the Boeing 737-900 aircraft was unable to pressurize above 10,000 feet. Oxygen masks did not deploy but some of the 140 passengers on board the plane reported suffering bloody noses, bleeding from the ears, and headaches. The flight was able to return to the airport safely and without further incident. Paramedics met with the flight after it returned to the Salt Lake International Airport and attended to about 10 passengers. No one was transported to the hospital. All were moved to a different flight. Is there a right way to exit an airplane? Delta Airlines released a statement after Sunday's incident, saying in part, "We sincerely apologize to our customers for their experience." The Boeing 737 aircraft was subsequently taken out of service and mechanics with Delta Airlines inspected the aircraft. The Boeing 737 was returned to service on Monday after technicians resolved the issue. Delta planes sit at their gates on June 13, 2022, at Salt Lake City International Airport, in Salt Lake City. (AP Photo/Rick Bowmer, File) According to the FAA, all pressurization incidents are investigated by the administration and regulations require airlines to file a report when aircraft systems or components require pilots to take emergency actions during flight. Pilots are reportedly trained to make controlled descents to below 12,000 feet if there is a pressurization issue during flights. This is because flights below that altitude do not require supplemental oxygen. The Boeing 737-900 is not part of the manufacturer's newer MAX fleet, which was the center of an investigation earlier this year when a door plug blew off during an Alaska Airlines flight over Oregon in January. However, the FAA recommended more thorough inspections of other Boeing aircraft, including the 737-900 model involved in Sunday's pressurization incident. FAA aircraft design regulations reportedly include extensive requirements to maintain cabin pressure and ensure there is a sufficient oxygen supply for both crew and passengers should there be a loss of cabin pressure. The Associated Press contributed to this report. Latest News Falcons receiver apologizes for violating longstanding NFL rule during TD celebration: 'Won't see that again from me' Here’s The Toy Insider’s ‘Hot 20’ toys expected to sell out this season Trump slams Howard Stern: 'He went woke' White dudes, Swifties and nerds: Pro-Harris groups build unity out of identity New Mexico's governor blasts Texas for placing razor wire on border between their states