Boeing has begun early development of a new single-aisle aircraft that could one day replace the 737 Max, the Wall Street Journal reported.

The project remains in its initial stages, involving internal design studies and exploratory discussions with engine manufacturers, according to people familiar with the matter. Earlier this year, Chief Executive Officer Kelly Ortberg met Rolls-Royce executives in the UK to discuss potential engine options, two of the people said. Boeing has also appointed a new senior product leader within its commercial division, previously tasked with developing a new aircraft type.

The Boeing 737 family is one of the most successful commercial aircraft lines in aviation history, evolving through multiple generations to meet the changing needs of airlines and passengers. The 737 was introduced in 1967 and has remained flying, and in production ever since.

Among the most commonly referenced variants are the 737 Next Generation (NG), the 737 MAX, and specifically, the 737-8. While they may seem similar on the surface, each represents a different stage in the aircraft’s development, with important distinctions in design, performance, and technology.

READ: Boeing 737 NG and MAX Compared: Evolution, Innovation, and Controversy

While the 737 Max introduced significant upgrades, its development and rollout were overshadowed by controversy and tragedy. Two fatal crashes involving the Max 8 led to an 18-month global grounding—sparking public fear, intense media scrutiny, and lasting skepticism.

Boeing, in a statement, said it remains focused on its recovery efforts, which are still ongoing.