In a major blow to Boeing, United Airlines CEO Scott Kirby has threatened to shun the aircraft manufacturer after the grounding of the carrier's fleet of Max 9 aircraft following the recent Alaska Airlines door blowout incident. Speaking on CNBC's "Squawk Box," Kirby expressed his frustration, stating that the Max 9 grounding has been the final straw for United.

Kirby revealed his concern over a potential five-year delay, which he considers the best-case scenario, for the certification of the 737 Max 10 by the Federal Aviation Administration (FAA). Consequently, United is now planning to develop strategies without incorporating the Max 10 into its future plans.

While United does not plan to cancel the orders of the Max jets, Kirby's public statements indicate that they will be removed from the airline's internal plans. These remarks come after sources informed Reuters that United had become "incensed" with a supplier that shares corporate roots with the airline. As a result of the grounding, United has been forced to sideline 79 Max 9 jets for which it had already sold seats.

Addressing the concerns of affected airlines, Stan Deal, the head of Boeing's commercial airplanes division, issued an apology for the disruptions caused by the Alaska Airlines incident. He acknowledged that Boeing had let down its airline customers and expressed deep regret for the significant inconvenience caused to them, their employees, and passengers. Deal also assured that Boeing was formulating a comprehensive plan to safely return these aircraft to service and improve quality and delivery performance. He pledged to support customers in accordance with the guidance of the FAA.

The FAA ordered the grounding of the 737 Max 9 following the door plug blowout on Alaska Airlines Flight 1282 on January 5. With 79 Max 9 aircraft in its fleet, United Airlines possesses the largest number of these jets compared to any other carrier. Since the incident, United and other US domestic airlines have been compelled to delay or cancel multiple flights.

On a positive note, Delta Air Lines CEO Ed Bastian expressed confidence in the company's decision to proceed with its Max 10 orders. Bastian highlighted that the Max 10 does not possess the same door-plug system as the Max 9, minimizing concerns about regulatory approval and delivery delays. However, there remain anxieties about potential delays and impacts to broader production plans.

Boeing has been banking on its newest offering, the larger-capacity Max 10, to compete with Airbus's A321neo and regain market dominance. Industry analysts emphasize that the full rollout of the Max lineup is essential for Boeing to stabilize its market share against Airbus and generate sufficient cash flow for the foreseeable future.

While canceling orders is rare due to deposit loss fears, airlines often manipulate their aircraft preferences or resort to public pressure to secure concessions. The ongoing situation raises questions about the outcome for both Boeing and United Airlines, as the industry awaits further updates on the resolution of the grounding and the FAA's clearance for the Max 10.

Overall, United Airlines' threat to shun Boeing highlights the growing challenges faced by the aircraft manufacturer in the wake of the Max 9 grounding, as both companies grapple with the fallout from the Alaska Airlines door blowout incident.