The failure of a door plug on an Alaska Airlines Boeing 737 Max 9 jet on 5 January continues the commercial air transport industry’s inauspicious start to 2024 in safety terms, after the total loss of a Japan Airlines Airbus A350 as the year began.

But what does this latest setback mean for airlines?

In the near term, multiple carriers – mainly based in the Americas – have been forced to ground Max 9s with the offending door plugs, which affects 171 aircraft globally, according to US Federal Aviation Administration figures.

Notably, however, the number of affected Max 9 aircraft is dwarfed by the number of Max 8s in service around the world, which Cirium fleets data puts at nearly 1,200. The latter variant is vastly more popular and so far unaffected by these particular safety concerns.

The biggest Max 9 operator is United Airlines, with 79 of the variant, followed by Alaska Airlines (65), Copa Airlines (21) and Aeromexico (19). Several airlines operate smaller numbers of Max 9 jets and not all airframes are affected by the grounding. 

On 10 January, Alaska Airlines extended the grounding of its Max 9s through 13 January and clarified that they would only fly again “when all findings have been fully resolved and meet all FAA and Alaska’s stringent standards”. A similar approach will apply at most carriers, whether under FAA jurisdiction or not, but indications are that some aircraft are expected to be flying again in the next few days.

Door plug

Source: NTSB

The incident prompted a directive from the FAA

While undeniably inconvenient for airlines and their passengers, the short-term capacity loss is not game-changing at an industry level, particularly given this is the low-season for most Northern Hemisphere carriers. Of course, should the groundings extend beyond days and weeks, the industry’s wider capacity shortages would be exacerbated – although there is no reason to believe that will happen at this stage. Should aircraft resume flights soon, it would suggest the required processes and fixes are relatively straightforward.

One significant unknown for airlines seeking more capacity in the coming months and years is what another potential quality-control incident at Boeing might mean for the certification timeline of the Max 7 and Max 10, and other programmes, and its ability to ramp-up production of 737 Max-family jets as planned, should regulatory scrutiny increase further and Boeing’s own processes need adjustments. At this stage, with formal findings on the cause of incident still to come, the remedies cannot be established, nor can blame be apportioned.

There is also the question of what this incident might mean for Chinese regulators, who reportedly recently green-lit the resumption of Max deliveries to that huge market, after airlines in the country began flying Max jets again last year. The lack of Max 9 orders among its carriers may mean the incident is not factored into its decision-making.

All told, while this is another challenge reputationally for Boeing and the Max programme – coming, as it does, after more issues such as the defective aft-pressure bulkheads in 2023 – the impact among airlines is on course to be limited.