w2bsa, Stephen, and Thomas: I call. I have a similar 40 year background in software engineering, with the last 25 years spent in safety-significant software systems for medical devices. All of your general comments on software design are correct -- software of any complexity will have faults and defects. What alarms me (pun intended) is that, in the FINAL verification and validation phase of this software development, Boeing is still finding defects in the avionics software that have the HIGHEST risk severity possible: loss of the aircraft. In my experience, finding such new show-stopping high-risk defects at this late stage of development is a huge red flag that indicates 1) the software architecture is flawed in its ability to detect, contain, and mitigate high-risk failures ("exception handling"), and 2) the software development PROCESS employed was itself flawed in its ability to find and mitigate to safe levels these high-risk defects("defect containment") during review, ins

(Written on 2020年 04月 11日)(Permalink)

Yes, the fact that he claims he didn't want to hurt anyone is a factor, but it is heavily outweighed by the potential severe harm his actions could have caused. And revenge would be a factor if some of the pilots and frequent fliers in this forum (who might take his actions as a personal threat) got ahold of this mechanic and beat him to death. So yes, let's keep him safely locked up and subject him to the full weight of the criminal justice system, which is quite capable of differentiating vindictive revenge from the protection of society (you and me) from the potential harm of this man's actions.

(Written on 2019年 09月 13日)(Permalink)

Thank you, Kimberly. A voice of reason ...

(Written on 2019年 08月 10日)(Permalink)

A root cause of the cargo door failures was the "straight-through" cargo doorway design in the DC-10 airframe, rather than the industry-standard tapered "plug" doorway. The plug design makes door failure very difficult, if not impossible, when the hold is pressurized. The straight-through doorway saved airframe weight and cost, but it removed a basic safety mitigation (the "plug"), leaving only the latch mechanism as the sole safety design mitigation. As Ken points out, the latch mechanism had several design flaws, including slack and bendable members, allowing baggage handlers to force the handle until they got the "green" fully-closed indication in the indicator window, while the latch pins were not actually all the way seated in the door frame. When pressurized during climbout, the inadequately seated pins failed and nothing stopped the door from blowing out.

(Written on 2019年 08月 09日)(Permalink)

I have a 1991 Bantam Air & Space Series reprint of the (c)1963 "The Electra Story". I think you're right about the Max recovering, assuming that the multiple root causes of the two accidents are all fixed. Chapter 4 of "The Electra Story" is titled "If Another One Goes Down ...". It is an apt comment for the current situation, as Jamar Jackson noted below.

(Written on 2019年 05月 10日)(Permalink)

Thanks, Ed. "The Electra Story" was one of my sources. I still have my old paperback. Just saw it is available as a Kindle book on Amazon.

(Written on 2019年 05月 10日)(Permalink)

I was wrong about "grounding". The Electra was put under operational restrictions, including a speed restriction. It was not grounded.

(Written on 2019年 05月 10日)(Permalink)

Another example of public opinion affecting an aircraft type is the Lockheed Electra. Pilots loved this aircraft, but shortly after its introduction in 1958, there were two horrific crashes. In the first crash in 1959, the initial investigation was hampered by the disintegrated state of the wreckage, but it was clear that the left wing had detached in otherwise nominal conditions at cruising altitude. Then on March 17, 1960, a second Electra lost BOTH wings at 18,000 feet, sending the fuselage into the ground like a missile, impacting at 600 plus mph. Unlike most aircraft accidents, there were no bodies and little debris on the ground, just a crater 40 by 30 feet. The crater made by the fuselage was so gruesome that local health, religious, and coroner officials tried to bar its excavation. It took 5 days to dig up the fuselage, compressed to a solid smoking mass 1/3 its length. Out of 63 souls on board, only the remains of 7 could be identified. And of course the press was reporting

(Written on 2019年 05月 10日)(Permalink)

I design and validate safety-significant software systems for a living. I've seen some useful observations in this forum over the past few weeks, especially from the pilots and system designers. And of course some chaff to be ignored. As the investigation proceeds, there are a couple of rookie mistakes to watch out for, as even experts sometimes fall into these traps: 1) When analyzing actions and decisions of people over time leading up to an accident, it is unfair to apply your present "perfect" knowledge of what happened. You must "walk the timeline" shoulder to shoulder with those people and assess their actions and decisions with what they knew at that moment in time. Doing the latter can uncover root-cause defects that might otherwise remain undetected. 2) Be careful of firm, unyielding comments about how the systems worked leading up to the accident; e.g., "when you flip this switch, this IS what happened". Everything in the system behavior should now be suspect unt

(Written on 2019年 04月 05日)(Permalink)

I have a vague memory that, early in 727's service, there were landing issues caused by an excessive nose-up attitude, which would cause the wings to block air to the 727's high-mounted horizontal stabilizers and stall them. The swaying you mentioned might have been caused by minor interference with the horizontal stabilizers. I think the fix included a faster landing speed and less nose-up. Any 727 pilots out there remember this?

(Written on 2019年 01月 18日)(Permalink)