Re: Boeing 737 and 737 MAX software

[robin.vowels@gmail.com]

On Saturday, April 6, 2019 at 8:16:22 AM UTC+11, Paul Rubin wrote:
> Does anyone know anything about this?  It has been under some criticism
> lately.
> 
> I have heard that the 777 software was almost entirely in Ada.  It also
> sounds as if Boeing's software operation may have slipped in recent
> years, not good news for the 737 MAX.

It seems that computers (and their computer programs) 
are not really suitable to take command of aeroplanes. 

This week appeared a re-run of the (then new) A320 fatal crash on 
a demonstration flight (Air Crash Investigations). 

In that case, the computer overrode the pilot, 
even when the pilot called for full power and climbing. 
Power was increased, but the computer failed to set 
the ailerons to climb, so that the plane continued 
flying horizontally at 30 feet and into trees at the end of the runway. 
The pilot had made a gross error in flying too close to the ground 
(30 feet), and the computer thought that the pilot wanted the 
plane to land. 

Tonight was screened on TV a report on the two new Boeing 737 MAX 
planes that crashed -- one in March this year and another in 
October last year. 

In both cases, a sensor failed; it was the input to the stall 
correction computer.  The computer sensed that the plane was 
about to stall (it wasn't), and put the nose down.  But the 
attitude of the planes was set to 60 degrees, which is an 
awfully steep dive, and not merely a minor correction to help 
the plane to avoid a stall. 

The pilot had five seconds to consult  a "check" list 
(a thick manual) as to what to do.  Even if he had been 
able to correct the problem (by adjusting the ailerons), 
the computer applied the stall correction again for 
10 seconds (which resulted in another steep dive), 
and the pilot had another 5 seconds to correct the 
problem. This 5/10-second cycle repeated ad infinitum. 
In one case, the plane was close to the ground, as it had 
not long before taken off from the runway. Each steep dive 
took the plane closer to the ground ... 

One major point of the TV report was that Boeing had never 
made mention of this software feature in any manual, 
so no pilots had been trained to deal with a situation 
in which software took over flying the plane. 

Three questions: 
1. Whatever happened to the stick shaker? 
2. Why was the dive so ridiculously steep? 
3. Why did not the autopilot save the plane 
   as it careered towards the ground? 

Usually the best operator of a plane is the pilot, 
and he should always be able to take over from 
any computer program (autopilot or stall correction) 
and to fly the plane manually in the event that the 
automatic equipment fails.