The Boeing 737 Max airplanes should be grounded until the cause of the weekend crash in Ethiopia crash is determined, the international president of the Transport Workers Union told CNBC on Tuesday.
"It is absolutely absurd that the FAA won't ground the flights until at least they get the voice and data recordings back form this latest incident," John Samuelsen said on "Closing Bell."
On Tuesday, the European Union joined other nations in temporarily suspending the planes' use in the wake of the crash — the second one in less than five months.
The United States, however, hasn't done so. The Federal Aviation Administration deemed the planes still airworthy in a notice Monday, saying it did not see a reason to ground the jets.
Late Tuesday the FAA released another statement saying it "continues to review extensively all available data and aggregate safety performance from operators and pilots of the Boeing 737 MAX. Thus far, our review shows no systemic performance issues and provides no basis to order grounding the aircraft. Nor have other civil aviation authorities provided data to us that would warrant action. In the course of our urgent review of data on the Ethiopian Airlines Flight 302 crash, if any issues affecting the continued airworthiness of the aircraft are identified, the FAA will take immediate and appropriate action."
While the latest crash is still being investigated, there are concerns the aircraft's automated systems played a role in bringing down a Lion Air Boeing 737 Max 8 in Indonesia in October. Boeing said Monday it is preparing updates to training manuals and software.
On Tuesday, airline workers spoke out about their fears. Flight attendants and ground crews from American Airlines and Southwest Airlines urged the companies to take the Boeing 737 Max out of service.
The Transport Workers Union represents more than 17,000 flight Southwest flight attendants, Samuelsen said. It also represents most of American Airlines' mechanics. The union sent a letter to both airlines asking them to ground the aircraft. American and Southwest on Tuesday told CNBC that they still have confidence in the aircraft and their crews.
However, Samuelsen is saving the bulk of his ire for the FAA.
"The FAA has to make a decision about whether they want to keep kowtowing to the airline industry," he said. "It's all about profits. The FAA needs to realize they work for the American people and they look after the safety of the American people."
However, Barry Valentine, former FAA acting administrator, said it's too soon to reach a conclusion about the Boeing 737 Max, since the cause of the latest crash is still unknown.
"A single event does not a trend make," he said on "Closing Bell."
In fact, he said there is a system within the airline industry that constantly broadcasts data about an aircraft's in-flight performance, flight characteristics and systems in real time.
"Thus far, for this particular airplane there has been no evidence that there have been any oddities or anomalies that would suggest that the airplane is not airworthy," Valentine said.
— CNBC's Leslie Josephs contributed to this report.