Boeing’s optional safety features, in part, could have helped the pilots detect any erroneous readings. One of the optional upgrades, the angle of attack indicator, displays the readings of the two sensors. The other, called a disagree light, is activated if those sensors are at odds with one another.

Boeing will soon update the MCAS software, and will also make the disagree light standard on all new 737 Max planes, according to a person familiar with the changes, who spoke on condition of anonymity because they have not been made public. Boeing started moving on the software fix and the equipment change before the crash in the Ethiopia.

The angle of attack indicator will remain an option that airlines can buy. Neither feature was mandated by the Federal Aviation Administration. All 737 Max jets have been grounded.

Ethiopian Airlines surpassed many carriers by becoming one of the first to install a simulator to teach pilots how to fly the new Boeing 737 Max 8, but the captain of the doomed Flight 302 never trained on the simulator, according to people close to the airline’s operations.

The people, who spoke on condition of anonymity because Ethiopian Airlines had not authorized disclosure of the information, said the carrier had the Max 8 simulator up and running in January, two months before Flight 302 crashed.
The pilot of Flight 302, Yared Getachew, who had 8,000 hours of flying experience including on the 737, took a refresher course on a different simulator in late September and early October, according to one person familiar with the airline, and was not due for another round of simulator training until after the crash on March 10.

It was unclear if the second pilot on Flight 302, the co-pilot, had trained on the Max 8 simulator. Nor was it clear if the airline had used the simulator for refresher courses it requires pilots to take every six months, or only to train new pilots. Still, use of the simulator by Ethiopian Airlines means the carrier was among the few in the world that not only had a working simulator for Boeing Max jets but was using it a few months after the first Max 8 crash, Lion Air Flight 610.