No more speculations. The accident is an exact copy of
this. Even the weight is almost the same. I would pay special attention at a couple of things.
First at page 40 says:
According to Douglas’ manager of aerodynamics and acoustics for the DC-9 and DC-g-80 programs, the roll stability is decreased significantly when the airplane is flying near its stall angle of attack. “It can be flown there, but it’s a very difficult thing to do.” The recorded data showed that, about the time of the first SSRS alarm, the airplane began a slight roll to the left which was reversed when a bank angle of about 8” was achieved. The airplane then rolled right about 16”, left about 33”, right about 35”, and then left; and initial impact occurred about 22” left roll as the airplane was rolling to the left. The data showed that the spoilers were used to counteract these rolls and that on two occasions almost full deflection (60”) was employed.
And at the next paragraph:
However, the airplane’s aerodynamic performance in this area was reduced by two factors: the rolls and the spoiler deflections used to counteract the rolling moments. During the last 6 seconds of the flight, the roll oscillations and subsequent spoiler deflections adversely affected the airplane’s climb performance by degrading the lift component by as much as 20 percent.
Second.
Moving to pages 73. At chapter 3.-Conclusions, subchapter 3.1.-findings.
Point 7 confirms the roll inestability of the MD when close to the stall.
Points 8,9 & 10 talks about TOWS of the CAWS and at the next page, under chapter 4.-Recomendations:
- Require the modification of the DC-g-80 series airplanes to illuminate the
existing central aural warning system (CAWS) fail light on the overhead
annunciator panel in the event of CAWS input circuit power loss so that the airplane conforms to the original certification configuration. (Class II,
Priority Action) (A-88-65)
- Develop and disseminate guidelines for the design of central aural warning systems to include a determination of the warning to be provided, the criticality of the provided warning, and the degree of system selfmonitoring. (Class II, Priority Action) (A-88-66)
If an american lawyer read this, Boeing could have troubles...