In the case of the Ethiopian Airlines crash of the 737 Max 8, there are two very different reports. The first is that the loss of control that crashed the plane and killed all onboard was related to the Maneuvering Characteristics Augmentation System ("MCAS") system that tragically appears to have caused the Lion Air crash last year. Indeed, early analysis indicates a similar pattern to the Lion crash indicating a struggle between the aircraft and crew.
Yet the other report is the statements of several witnesses on the ground, as reported by Reuters, who reported loud noises, smoke streaming from the aircraft, as well as clothing and papers escaping from the plane before it crashed.
From the Reuters story: "Half a dozen witnesses interviewed by Reuters in the farmland where the plane came down reported smoke billowing out behind, while four of them also described a loud sound. "It was a loud rattling sound. Like straining and shaking metal," said Turn Buzuna, a 26-year-old housewife and farmer who lives about 300 meters (328 yards) from the crash site.These two reports are entirely inconsistent.
"Everyone says they have never heard that kind of sound from a plane and they are under a flight path," she added. Malka Galato, 47, a barley and wheat farmer whose field the plane crashed in, also described smoke and sparks from the back. "The plane was very close to the ground and it made a turn... Cows that were grazing in the fields ran in panic," he said.
Tamirat Abera, 25, was walking past the field at the time. He said the plane turned sharply, trailing white smoke and items like clothes and papers, then crashed about 300 meters away."
In the event of a MCAS or other-caused loss of control of the aircraft by the pilots, the plane would make no explosive-like sounds, nor would there be smoke and debris escaping from the aircraft. Ground witnesses would have observed an intact airplane dive steeply into the ground without explosive-like sounds.
The statements of the ground witnesses appear consistent with a bomb or other explosion that opened the fuselage. A fire that caused an explosion or a bomb could plausibly damage data cabling, instrumentation and other electronics, making the cockpit controls inoperative or partially compromised‐perhaps approximating the symptoms of a MCAS-like failure or even triggering a MCAS failure-event by damaging a crucial sensor.
The probability of both MCAS and explosive events happening simultaneously seems slim, however if the statements by the ground witnesses hold up to forensics investigations, and if as initial analysis shows, there was a MCAS-related loss of control, then this coincidence must not be ruled out.