Boeing's 737 Max 9 aircraft: Here's what to know

737 Max is Boeing's most popular series

Boeing's 737 Max 9 entered the spotlight after an Alaska Airlines flight was forced to make an emergency landing on Jan. 5 when a section of the plane blew out mid-flight.

No injuries were reported after the jet lost a door-plug panel while heading to Ontario, California. It was forced to return to Portland International Airport in Oregon just minutes after takeoff.

The incident prompted a temporary grounding of every Boeing 737-9 Max with a plug door that will last until the Federal Aviation Administration (FAA) says it can determine that each plane can safely return to operation. The FAA said it is waiting for Boeing to provide updated instructions to operators for inspections and maintenance so that it can provide a thorough review.

FAA PROBING WHETHER BOEING FAILED TO ENSURE PLANES WERE SAFE TO OPERATE

In the meantime, Boeing said it will work with the National Transportation Safety Board to find out what caused the incident.

Days after the incident, Boeing CEO Dave Calhoun held an all-hands safety meeting with staff.

"We’re going to approach this, No. 1, acknowledging our mistake," Calhoun said. "We’re going to approach it with 100% and complete transparency every step of the way."

What to know about the 737 Max series

The 737 Max 9 is part of Boeing's 737 Max series, which is described as a more fuel-efficient and quieter version of the planes it replaces. It cuts fuel use and emissions by 20%, and it produces a 50% smaller noise footprint than other planes, according to Boeing's website.

Boeing's order and delivery figures on its website show that there have been 439 total orders for the 737 Max 9 since the program began. The company has already delivered 217 aircraft.

BOEING CEO HOLDS ALL-EMPLOYEE SAFETY MEETING FOLLOWING 737 MAX INCIDENT: ‘ACKNOWLEDGING OUR MISTAKE’

Alaska Boeing 737 MAX 9

An Alaska Airlines Boeing 737 Max 9 is shown at Seattle-Tacoma International Airport on Jan. 6, 2024, in Seattle. (Stephen Brashear / Getty Images)

On Tuesday, the company announced that it had delivered 396 Boeing 737 jets throughout fiscal 2023, including 387 Max planes. The other nine are the 737 Next Generation planes, an older generation of aircraft.

737 Max 9

The 737 Max is the company's best-selling series. However, the 737 Max 9 is the least popular version, according to Skift, an industry news site.

The Max 9 is only slightly bigger than the 737 Max 8 and Max 7 in terms of the maximum number of seats. It has 220 seats while the Max 8 and Max 7 have 210 and 172, respectively. The 737 Max 10 is the biggest of the variants with 230 seats.

The 737 Max 8 model made headlines in 2018 and 2019 when it was involved in a pair of fatal crashes just months apart.

LATEST 737 MAX INCIDENT CREATES MORE HEADACHES FOR BOEING

In October 2018, a Lion Air flight crashed in Indonesia, killing all 189 people aboard. In March 2019, an Ethiopian Airlines flight crashed, killing all 157 passengers and crew.

Alaska Airlines blowout

Authorities are investigating after an Alaska Airlines Boeing 737 Max 9 lost a section of the plane mid-flight and was forced to make an emergency landing on Jan. 5, 2024. (NTSB / Fox News)

In the wake of the crashes, the FAA and several of its international counterparts grounded the Max to review the aircraft’s safety – moves that caused Boeing to cut its production in the spring of 2019 and post its largest-ever quarterly loss that summer.

Carriers that fly the 737 Max 9

Both Alaska and United Airlines have the 737 Max 9 model in their fleets. 

United has 79 Boeing 737 Max 9 aircraft and Alaska operates 65 Max 9 planes.

Southwest, Delta, JetBlue, Spirit and American Airlines do not have the 737 Max 9 in their fleets.

Southwest told FOX Business that the Max 8 and Max 7 models in their existing fleet do not have the exit-door plug like the one involved in the Alaska Airlines incident on Jan. 5. Overall, its fleet and operation are unaffected.

Ticker Security Last Change Change %
ALK ALASKA AIR GROUP INC. 53.16 +0.56 +1.06%
UAL UNITED AIRLINES HOLDINGS INC. 97.44 +0.61 +0.63%
DAL DELTA AIR LINES INC. 63.38 -0.53 -0.82%
LUV SOUTHWEST AIRLINES CO. 33.01 +0.60 +1.85%
AAL AMERICAN AIRLINES GROUP INC. 14.61 +0.09 +0.62%

Meanwhile, United and Alaska canceled hundreds of flights because of the grounding. United told FOX Business that it was trying to minimize cancellations by using other aircraft types when possible.

Alaska said in a note on its website that it continues to "experience disruption to our operation with these aircraft out of service."

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FOX Business' Eric Revell contributed to this report.