"When it was rolled out, MCAS took readings from only one sensor on any given flight, leaving the system vulnerable to a single point of failure. One theory in the Lion Air crash is that MCAS was receiving faulty data from one of the sensors, prompting an unrecoverable nose dive.
In the software update that Boeing says is coming soon, MCAS will be modified to take readings from both sensors. If there is a meaningful disagreement between the readings, MCAS will be disabled."
"When it was rolled out, MCAS took readings from only one sensor on any given flight, leaving the system vulnerable to a single point of failure. One theory in the Lion Air crash is that MCAS was receiving faulty data from one of the sensors, prompting an unrecoverable nose dive.
In the software update that Boeing says is coming soon, MCAS will be modified to take readings from both sensors. If there is a meaningful disagreement between the readings, MCAS will be disabled."
https://www.nytimes.com/2019/03/21/business/boeing-safety-fe...