Both the Lion Air and Ethiopian B737 MAX aircraft were not equipped with two safety features in their cockpits. The two devices were optional and there were extra charges for them. The optional safety features were the the angle of attack indicator which displays the readings of the two sensors and another device called a disagree light which activates if the sensors are not in agreement.
Optional features can be purely cosmetic. Other upgrades include communication, navigation or safety systems. Both cosmetic and avionics upgrades can cost hundreds of thousands of dollars and some airlines have opted not to buy them.
Now sources are saying Boeing will make one of those safety features standard as part of a fix to get the planes in the air again. There will be an update to the MCAS ()software and those sources say the disagree light will become standard on all new 737 MAX planes.
This information comes at the same time that new insights are being uncovered from the cockpit voice recordings of the Lion Air flight that crashed. The pilots are heard searching the aircraft’s manual and emergency procedures to find a way to gain control of the aircraft. The same issue had occurred in the next to last flight of the same aircraft at Lion Air, and the accident crew was aware of that, but thought the issue had been resolved by maintenance.