A Delta flight made an emergency return to Minneapolis-St. Paul International Airport and passengers got an eye-opening look at why.
The Dominican Republic-bound flight took off around 7:10 a.m. Monday, but an hour later returned to the airport. The flight crew had noticed vibration from the engine shortly after takeoff, FOX 9 reports. The Boeing 737 circled for roughly 25 minutes to burn fuel before making the emergency landing, KSTP says.
"These fellows did the right thing by immediately landing even though they knew there was no major danger," Ross Aimer, a retired pilot for United Airlines and CEO of Aero Consulting Experts, told FOX 9.
An emergency was declared so the flight could get priority from air traffic control, and the plane landed without incident, FOX 9 reports.
Delta confirmed the outer casing, or the engine cowling, had separated, but didn't speculate on the cause of the equipment failure. Aimer told FOX 9 the cowling is not actually bolted down – it has quick-disconnect latches that come together and at high speeds sometimes, if not latched properly, can come apart.
After a three-hour delay, a different aircraft brought the 149 passengers to their destination, according to media reports.
Here's a photo a passenger shared with FOX 9 and KSTP:
These types of incidents are somewhat unusual. In 2008, the National Transportation Safety Board released a report after it investigated incidents in which engine cowlings separated during flight – this happened 41 times worldwide between 1992 and 2008, according to the NTSB. The NTSB concluded that procedures for making sure cowlings are latched properly may be inadequate.
Last November, an Airbus A319 returned to Chicago's O'Hare International Airport when the engine cowling detached shortly after takeoff. The plane landed safely without incident, according to the Chicago Tribune. Last month, a Boeing 777's engine casing was missing after a flight from Newark, New Jersey to Mumbai, India. The Mumbai Mirror reports that officials determined the casing fell off during takeoff in Newark because it was not fastened properly.