The union representing American Airlines pilots wants the United States Congress to reject a proposed extension that would enable Boeing to keep its old cockpit alert system in place on newer plane models.

The union is demanding an upgrade to the alert system on the latest variants of 737 Max jets, according to Flying Magazine.

Boeing argued that keeping the old system in place would avoid potential pilot confusion that could lead to deadly outcomes.

In 2020, Congress passed a two-year exemption — The Aircraft Certification, Safety, and Accountability Act — that allowed the airplane manufacturing company to use the old alert system on any planes certified before the end of this year, according to Aviation Pros.

Boeing is working on newer models — MAX 7 and MAX 10 — but they will not be released this year as they are still in the middle of the Federal Aviation Administration certification process. Boeing is asking Congress to extend the period covered by the 2020 law.

News of Boeing’s situation has not gone down well with the Allied Pilots Association (APA), the union representing over 15,000 pilots of American Airlines.

“We oppose any extension of the exemption and don’t agree with Boeing’s claim that pilots could become confused when moving from an airplane without the modern alert system to one that is equipped with it,” said APA President Capt. Edward Sicher. “Nothing could be further from our flight deck reality.”

Sicher took a hammer to Boeing’s claim of pilot’s confusion while stating that the company’s 757 and 767 models are “substantially different airplanes yet operate under a single certificate.”

He noted that, despite their differences, pilots had flown both models within a short period of time, often on the same day.

Contrary to Boeing’s argument, Sicher claimed that the upgraded alert system would help mitigate “pilot startle-effect and confusion during complex, compound system malfunctions.”

“Once these systems are installed and pilots have been properly trained on them, our crews will be better able to identify system failures and prioritize corrective actions that could save lives,” Sicher added.

Sicher’s statement comes after the FAA suggested in a letter to the U.S. Senate that Boeing would not be able to certify the MAX 10 before next summer. A previous letter from the FAA had also stated that the MAX 7 would likely not meet the deadline on its current schedule.

Should lawmakers refuse to extend the deadline, Boeing might end up at least canceling the MAX 10 project, according to Boeing CEO Dave Calhoun. He explained, “This is a risk I’m willing to take. If I lose the fight, I lose the fight,”

In addition to the APA, the families of victims of the two 737 MAX crashes are also against giving Boeing more time. Around 800 relatives and friends of the victims signed a letter to Congress in July stating Calhoun had resorted to bullying Congress.

While it is not clear what decision lawmakers would come to before the deadline expires, Senator Roger Wicker (R-MS), a ranking member of the Senate Commerce, Science, and Transportation Committee, filed an amendment to the National Defense Authorization Act that would give Boeing the extension it seeks should the legislation pass.