A range of ground-based Southwest Airlines Boeing 737 MAX 8 aircraft will be deployed at Victorville Airport in Victorville, California, on March 26, 2019.
Mike Blake | Reuters
Boeing did not tell its largest customer, 737 Max, that a standard security feature that warned pilots of bad sensors had been disabled on the jets, the Wall Street Journal reports.
Southwest Airlines did not know that the default security alert was showing was turned off. The alarm informed the pilots when a sensor referred to as a "pitch angle flag" transmitted erroneous data on the nose of the aircraft nose.
Boeing had installed a new anti-stall system on the 737 Max and manufactured the safety alert ̵
Federal Aviation Administration security inspectors and regulators were also unaware of the change, government and industry officials said. Southwest did not know about it The change for more than a year after the new 737 Max jets went into service. Following the fatal crash of a Lion Air flight in Indonesia, Southwest asked Boeing to initiate the jets' safety alert test in its fleet.
Southwest said in a statement to CNBC that Boeing had stated in its documentation that the security alert, known as "Angle Attack Attack," was operational at 737 Max.
Delivered (prior to the Lion Air event), Boeing's AOA Disagree lights have been shown to work for all MAX aircraft, regardless of the selection of optional AOA displays on the Primary Flight Display (PFD). The manual documentation provided by Boeing as part of the Southwest MAX commissioning showed that AOA Disagree Light worked in the aircraft, much like the lights in our NG series. After the Lion Air event, Boeing informed us that the AOA Disagree Lights will not work without the MAX aircraft's optional AOA displays. At that time, Southwest installed the AOA Indicators on the PFD, which led to the activation of the AOA Disagree lights – both elements now serve as an additional cross-check for all MAX aircraft.
The FAA even considered grounding Southwest's Max fleet during weighing, whether the airline's pilots needed additional safety alert training or not. But these discussions were brief and did not go on according to the magazine.
Boeing said in a statement to CNBC that the warning label "attack angle" would be included as a standard max feature.
"When we resume our service, the AOA alert will default to all customers and it will be possible to include the AOA indicator for free," said a Boeing spokesman. "This change will be made on all MAX aircraft – production and retrofitting."
Southwest could not be reached immediately for a comment.
The Boeing 737 Max was grounded in March by the FAA in the wake of deadly crashes in Indonesia and Canada. Ethiopia killed 346 people.
Several large airlines have extended the cancellation of Max flights in the summer. American Airlines canceled Max flights for a total of 115 flights per day until 19 August, while Southwest was canceled until 5 August and United until 5 June.
Read the full story in the Wall Street Journal