Actually Boeing sent out a memo to the pilots of the MAX after Lion Air crash explaining what may have caused it and what to do. Here is basically what is happening. Upon climb out the pilot will engage the autopilot with it in NAV mode. At this time flaps are still extended for climb out and the aircraft maintains the climb as indicated on the FMS to the assigned altitude. Once the flaps are fully retracted the MCAS engages. At this point the MCAS looks at several things but one being the Vertical Pitch Indicator to either adjust the trim up or down as needed for climb or possibly level flight if needed at this point. The Vertical Pitch Indicator is reading on some MAX 8's 10-20 degrees higher than what the aircraft actually is pitched at. This engages the MCAS to lower the Trim to level the aircraft as needed. Well at this point the plane over pitches nose down because the Vertical Pitch Indicator is saying the plane is pitched up, which it is not. The pilot then will use the Trim on the yoke to trim up also pull back on the yoke and both the MCAS and the pilot are fighting to keep the plane level. Once the pilot stops with the trim adjustment the MCAS goes to full trim down due to adjust for the 10-20 degree increase in the Vertical PItch Indicator it was getting, which is incorrect. At this point the aircraft is sadly most likely in downward angle and unable to recover from it. Boeing did say in a memo what could be done to help stop this during flight. The pilot's can manually override all autopilot functions including MCAS, either first or at that point put the Flaps extended one notch to disengage the MCAS.
Actually Boeing sent out a memo to the pilots of the MAX after Lion Air crash explaining what may have caused it and what to do. Here is basically what is happening. Upon climb out the pilot will engage the autopilot with it in NAV mode. At this time flaps are still extended for climb out and the aircraft maintains the climb as indicated on the FMS to the assigned altitude. Once the flaps are fully retracted the MCAS engages. At this point the MCAS looks at several things but one being the Vertical Pitch Indicator to either adjust the trim up or down as needed for climb or possibly level flight if needed at this point. The Vertical Pitch Indicator is reading on some MAX 8's 10-20 degrees higher than what the aircraft actually is pitched at. This engages the MCAS to lower the Trim to level the aircraft as needed. Well at this point the plane over pitches nose down because the Vertical Pitch Indicator is saying the plane is pitched up, which it is not. The pilot then will use the Trim on the yoke to trim up also pull back on the yoke and both the MCAS and the pilot are fighting to keep the plane level. Once the pilot stops with the trim adjustment the MCAS goes to full trim down due to adjust for the 10-20 degree increase in the Vertical PItch Indicator it was getting, which is incorrect. At this point the aircraft is sadly most likely in downward angle and unable to recover from it. Boeing did say in a memo what could be done to help stop this during flight. The pilot's can manually override all autopilot functions including MCAS, either first or at that point put the Flaps extended one notch to disengage the MCAS.