Aviation analysts believe Boeing will eventually need to develop a clean-sheet narrowbody aircraft to remain competitive, but say the company must first complete its current certification backlog, reports New York's Business Insider.

Boeing has not launched a clean-sheet commercial jet since the 787 Dreamliner in 2004, instead opting for upgrades to existing models. The 737, its narrowbody workhorse, has undergone four generational updates since 1967 and is nearing the end of its upgrade potential.

A September report from The Wall Street Journal suggested Boeing is developing a 737 successor. However, Boeing's vice president for commercial marketing, Darren Hulst, said the company is "not close to launching a new airplane," though it continues to explore new technologies.

Analysts say a next-generation single-aisle aircraft will require a new, highly efficient engine. Boeing CEO Kelly Ortberg reportedly visited Rolls-Royce earlier this year to discuss its UltraFan technology, which could break the firm's long-standing reliance on CFM International.

CFM is developing an open-rotor engine, but it may not be ready until the mid to late 2030s due to technical hurdles. Rolls-Royce's smaller UltraFan variant could offer an alternative, though no official partnership has been confirmed.

Boeing still needs to certify the 737 Max 7 and 10 variants and the 777X, all delayed amid heightened scrutiny following the Max crisis. Analysts say completing these programmes is essential before launching a new aircraft.

Boeing stock is up nearly 23 per cent year-to-date. The company has increased Max output to 42 jets per month after a regulatory cap of 38, imposed following the Alaska door plug incident.

Analysts Richard Aboulafia and Jeff Windau agree that Boeing should begin discussing a new design soon, even if a launch is a decade away. They credit Ortberg's leadership with improving production quality and investor confidence.

Boeing says it remains focused on certifying current models and delivering its 6,000-jet backlog, while continuing to evaluate market needs and advance technologies for future products.