A union for 28,000 American Airlines cabin crew told Boeing's CEO its members are scared of getting back on the 737 Max

• The head of a union representing 28,000 American Airlines flight attendants wrote a letter outlining its members' safety concerns about returning to the Boeing 737 Max when it is ungrounded.
• Lori Bassani, head of the Association of Professional Flight Attendants, told Boeing CEO Dennis Muilenburg that her members will "refuse to walk onto a plane that may not be safe."
• In the letter, seen by Reuters, she said that the union wants more information to satisfy itself of the plane's safety, even after it is cleared to fly by the US Federal Aviation Administration.
• Boeing promises that the plane will be one of the safest ever to fly when it returns to the skies after two fatal crashes that killed 346 people.
• Visit Business Insider's homepage for more stories.

The head of a union representing 28,000 American Airlines flight attendants told the CEO of Boeing that her members will refuse to get back on the 737 Max until their safety fears have been put to rest.

The letter, from the head of the Association of Professional Flight Attendants (APFA) to Boeing boss Dennis Muilenburg, said that they want more of a say in the process of bringing the plane back to the skies.

The Reuters news agency saw the letter, signed by APFA president Lori Bassani. It said: "The 28,000 flight attendants working for American Airlines refuse to walk onto a plane that may not be safe and are calling for the highest possible safety standards to avoid another tragedy."

American Airlines had 24 of the 737 Max jets in its fleet when the second crash in a few months took place in Ethiopia, prompting its grounding by regulators around the world.

The two crashes - a Lion Air plane in October 2018 and an Ethiopian Airlines plane in March 2019 - combined killed 346 people.

According to Reuters, Bassani wrote that the union wants more information to assess how safe it is to put its members back on the planes.

They asked to make their own assessment even after the US Federal Aviation Administration certifies it to fly again.

Reuters wrote that a Boeing spokesman said CEO Dennis Muilenburg "received the letter and will be responding soon."

The final report from Indonesian investigators into the Lion Air crash pointed to Boeing's faulty design of the plane as the main factor behind the crash.

The report said Boeing did not inform pilots of features in the flight control system which ended up bringing the plane down, It also criticized missteps from the airline and the pilots on board the fatal flight.

Boeing has made updates to the plane, and promises that it will be one of the safest planes ever to fly when it returns - which is expected at the end of this year at the earliest.

The FAA said that it will not approve the updates and allow the plane to fly until it is convinced of its safety. Airlines, including American Airlines, have made similar promises.

The APFA letter was sent on Wednesday, the second day that Muilenburg testified to Congress about the planes.

Muilenburg directly apologized to victims' families, and said that his company "made some mistakes" in the plane's design. Lawmakers accused Boeing of "pushing profits over quality and safety."

Bassani testified about the 737 Max to the House Committee on Transportation and Infrastructure in July, calling on the FAA to ensure the plane is totally safe before it returns.