American Airlines Boeing 737 Max jets are parked at a Tulsa facility in May. (American Airlines/Reuters)

Boeing’s efforts to save its customers money contributed to the “fatal mistake” of failing to give pilots the crucial information and training they needed to safely fly 737 Max jets, according to the president of a union representing 15,000 American Airlines pilots.

“Unfortunately, as pilots know, improvements in aviation are often written in the blood of the unfortunate victims of airplane accidents,” Capt. Daniel F. Carey said in remarks prepared for a hearing Wednesday before a House aviation subcommittee.

Two new Boeing 737 Max jets crashed within five months — one in Indonesia and the other in Ethiopia — killing 346 people. Investigators say pilots in both crashes were unable to control an automatic anti-stall system that kept pushing the planes’ noses downward, based on faulty information from a sensor. Three days after the Ethio­pian Airlines crash in March, the Federal Aviation Administration followed its counterparts in other countries and grounded the Boeing 737 Max 8 and Max 9. The jets remain grounded.

Carey, president of the Allied Pilots Association, said Boeing’s mistakes were also compounded by company engineers who created the automated feature, known as the Maneuvering Characteristics Augmentation System, or MCAS. The feature was meant to give the planes the same feel to fly as their predecessors but were not well integrated into the plane, Carey argues.

“The point was to provide Boeing’s customers with a new advanced aircraft while minimizing the training cost associated with a different aircraft certification,” Carey wrote in his planned testimony.

Wednesday’s hearing is part of a broader probe by the House Transportation Committee looking into the causes of the Max tragedies, decisions by Boeing and oversight by the FAA. Members are also scheduled to hear from the industry group Airlines for America, the Association of Flight Attendants-CWA, former FAA administrator Randy Babbitt and Capt. Chesley B. “Sully” Sullenberger III.

Investigators say faulty information from an external sensor on both planes caused the MCAS to repeatedly misfire, contributing to the crashes. Carey said such a “single-point-of-failure design” meant that “any redundancy to the system, if it failed, was completely dependent on the Captain and First Officer of the aircraft.”

“The huge error of omission is that Boeing failed to disclose the existence of MCAS to the pilot community,” Carey wrote. “The final fatal mistake was, therefore, the absence of robust pilot training in the event that the MCAS failed.”

Boeing said in a statement, “We are working with the FAA, global regulators, airlines and pilots to provide them the information they need, to re-earn their trust and know we must be more transparent going forward.”

Carey also raised questions about the FAA’s certification process for the 737 Max.

“Is the FAA sufficiently independent of the manufacturers so as to provide a legitimately rigorous audit of the manufacturers’ design and engineering?” he asked. “Is the FAA sufficiently equipped to ensure that pilot training protocols are vigorous and robust as aircraft are becoming more and more technologically sophisticated?”

Carey asked whether an FAA aircraft certification, “such as a 737 designation from 1967,” should have a date for termination or sunset.

Carey said that during a meeting of top FAA officials, pilots union representatives and U.S. airline officials in April, “FAA officials highlighted a critical checklist that Boeing directed pilots to use to recover the Max after an MCAS misfire. The FAA official stated that this critical checklist had not been validated since 1967, noting that the 737 has been dramatically modified many times since.”

He said an FAA official also pointed to “challenging ‘elevator loads’ confronting pilots when this checklist is executed.”

Acting FAA administrator Daniel Elwell has said that the Ethio­pian Airlines pilots were flying too fast and that speed was one of many factors in the crash. A higher speed can make it more difficult to adjust the plane’s horizontal stabilizer, which is one step in the emergency checklist.

The FAA denied that agency officials contended in the meeting that “this critical checklist had not been validated since 1967.”

“It was a very technical conversation, with pilots and operators, absent any commentary, and 1967 was never referenced,” the FAA said. The checklists are updated routinely under the auspices of the FAA’s Flight Standardization Board and airlines and unions have a voice in that process, the agency said.

Union officials reiterated Carey’s description.

During a hearing with Elwell last month, Rep. Sam Graves (R-Mo.) said the Ethio­pian pilots “accelerated throughout the entire flight” and “that fundamental error appears to have had a domino effect on events that followed,” adding that he believed U.S.-trained pilots would have avoided disaster.

Carey said “to make the claim that these accidents would not happen to U.S.-trained pilots is presumptuous and not supported by fact.”

He added that while his experience has shown him that “the Boeing Corporation has manufactured superbly engineered and designed aircraft over many decades,” in the case of the Max, “I completely agree with the Boeing CEO’s assessment that the company let down the public with catastrophic consequences.”

Carey said an MCAS software fix developed by Boeing has made “significant positive changes.”

“There are now redundancies embedded in the aircraft in the event of the ‘firing’ of MCAS,” he said, but he added that his members “remained concerned about whether the new training protocol” will ensure safety.

In an interview, Carey said Boeing recently invited two association pilots to try a simulator with the software fixes but then disinvited them, further straining trust.