Even if Boeing (NYSE:BA) does complete the 737 MAX recertification flight in June as it hopes, the plane is unlikely to fly passengers until September at the earliest, according to an online post from Friday.

The 737 MAX has been grounded since March 2019 after a pair of fatal accidents, but Boeing, after revamping the control software on the plane and reworking some of the wiring, is expecting to win regulatory approval to get the plane airborne again in the third quarter, which starts in July. That would mark an important milestone for Boeing, which bled through $4.7 billion in the first quarter in part due to 737 MAX-related expenses.

A Boeing 737 Max on a tow.

Image source: Boeing.

After a series of misstarts. Boeing appears to be nearing regulatory approval. But a report from The Air Current, an online publication that tracks Boeing and commercial aviation, said that even if the test flight goes as planned, there are still other milestones that need to be accomplished. For instance, the Federal Aviation Administration (FAA) and other regulators will have to hold a review board to determine final training requirements for those flying the plane and run engineering simulator tests to validate the functionality of new software.

The efforts have been delayed by the COVID-19 pandemic, which has made it more difficult for the FAA and international regulators to coordinate approval work.

At launch, the 737 MAX was expected to be a best-seller, but the pandemic has eroded demand for new planes and cut into Boeing's order book. But even if initial demand is tepid, the recertification is a key step in Boeing's effort to cut its cash burn and normalize operations.

Boeing is taking a conservative approach to new plane manufacturing due to the pandemic, with a key supplier saying earlier in the week it has been asked to scale back production of components for the 737 MAX.