United Airlines (UA) announced on Friday that it would ground its fleet of 737 MAX planes until June 4, 2020, at the earliest, resulting in the cancellation of thousands of flights each month as fallout from Boeing’s troubled flagship ricochets across the economy.

Back in October, the air carrier originally decided to scrap the 737 MAX until January, joining Southwest and American after the plane’s grounding in March in the wake of two fatal crashes.

However, that hiatus was complicated by Boeing’s (BA) decision to halt production on the 737 MAX indefinitely amid resistance from regulators. United’s move on Friday underscores the lack of confidence major carriers appear to have in the plane, and calls into question when Boeing will be able to normalize production on the MAX — if it ever does at all.

“Since the grounding of the Boeing MAX aircraft in March 2019, United has gone to great lengths to minimize the impact on our customers’ travel plans,” the carrier said in a statement. “We’ve used spare aircraft and other creative solutions to help our customers, who had been scheduled to travel on one of our MAX aircraft, get where they are going.”

With the grounding expected to last until next year, United said its action would result in dozens of flights per day being cancelled between December and June – translating into thousands of voyages per month that won’t be made.

“During this period, we’ll continue to take extraordinary steps to protect our customers’ travel plans,” United said.

“Moving forward, we’ll continue to monitor the regulatory process and nimbly make the necessary adjustments to our operation and our schedule to benefit our customers who are traveling with us,” United added.

Boeing’s announcement to temporarily shut down MAX production is expected to take a toll on the broader economy and the aviation industry, and prompted President Donald Trump to call CEO Dennis Muilenburg to assess the impact, according to a New York Times report this week.

It also highlights how pivotal the company— a Dow component — is to U.S. growth.

“With the MAX return to service date still unknown, pushing our timeline back to early June is what is best for our customers and our operation,” a United source told Yahoo Finance on Friday.

“By moving the return to service date back more than just a month - as we have done previously throughout 2019 - it allows us to have more certainty by providing our customers and our operation a firmer and more definitive timeline,” this person said.

—Yahoo Finance’s Adam Shapiro contributed to this report.

Javier David is an editor for Yahoo Finance. Follow Javier on Twitter: @TeflonGeek

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