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Comment by yongjik | Hacker News Reader

With all due respect, this sounds too much like the kind of armchair quarterbacking that routinely appears on HN when avionics/politics/astronomy is mentioned, where a lone programmer feels competent enough to criticize an industry for missing "something obvious".

I mean, this particular change might have saved the particular 737, but I'd rather hear it from someone who actually knows how 737s fly.

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Philip Greenspun is a highly experienced pilot:

https://philip.greenspun.com/flying/milestones

I too have hundreds of flights and am also a programmer, but I would not assume having both skills would make you anything more then an armchair quarterback. If you have not written code that runs planes, what knowledge are you basing your idea off of. IMO.

i too also play games, but i wouldn't assume to tell a game developer how to write their code.

I agree - being a pilot and a programmer is neither a necessary nor sufficient condition for being able to diagnose and solve an issue in a system as complex as a modern airliner. In fact I don't think any individual is capable of doing so on their own; maybe the sole exception being someone like the engineering lead of avionics for the 737 Max, who is probably not a pilot, and probably only a programmer in so far as it was a component of their engineering education.

Honest question, is his experience in small aircraft applicable at all to jetliners? How much carryover, beyond core theory of flight dynamics, is there from piloting a single prop to an Airbus or even a regional jet?

His resume includes:

- FAA ATP AMEL and ASEL certificate with CL-65 SIC rating and Part 121 experience; CE-510S rating (single pilot, Cessna Mustang)

- Helicopter ATP

- single-engine seaplane rating at the commercial level

- FAA Flight Instructor certificate with airplane single-engine, airplane multi-engine, helicopter, instrument airplane, and instrument helicopter ratings

He has also worked as a commercial pilot for Delta/Comair. See https://philip.greenspun.com/flying/resume

He part owns a Pilatus PC-12, which is pretty much a single engine regional jet. It isn't your grandfather's Cessna.

Turboprop

He has first officer experience flying a CL-65 Canadair Regional Jet.

He doesn't seem to be an experienced owner of a home outdoor thermometer though.

Or if he is, I need to know where he found one that goes to 452 degrees and why he even needs that much range. ;)

The thermometer sensor and circuitry might be perfectly ok, still the 452 number might be a single digit gone bonkers in the panel, so that data being transmitted (maybe also recorded?) is ok while the readout is plain wrong. A human acting according data being shown there might react very differently from someone reading the temperatures log. Sometimes software problems can be awfully subtle.

Digital thermometers usually have triple digits to be able to display numbers in the low 100's. I could see one of them failing in a weird way and displaying 452.

I was as confused as the other commentators by this post until I realized that fixermark is thinking of analog thermometers with a physical dial, while we (and probably the author as well) are envisioning electronic thermometers with digital displays.

BBQ lid? Many have thermometers that go higher than this (say, 700F), and they're often outdoors.

How else would you know there is a wildfire outside?

A pilot is not a programmer. A minor, but important distinction.

EDIT: Aaaand I'm an idiot. My bad.

Philip Greenspun is, in fact a programmer. He's probably best known in these circles for the quote "Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp."

It is possible to be both a pilot and a programmer.

This is referred to in the industry as a "Dr. McNinja scenario."

(... nobody refers to it as that ;) ).

Are you claiming Greenspun is not a programmer?

https://en.wikipedia.org/wiki/ArsDigita

https://philip.greenspun.com/teaching/

not only is he a programmer, but he has opinions on teaching programming.

I agree that we frequently see this on HN in regards to aviation. However, I don;t think it applies to Greenspun. He's a knowledgeable and active pilot himself.

Lots of people are, that doesn't mean they aren't armchair quarterbacking. I know how to fly airplanes and helicopters, does that make me an expert on the flight dynamics of 737 MAX?

According to Wikipedia he flew for Delta Airlines/Comair https://en.wikipedia.org/wiki/Philip_Greenspun.

That still doesn't mean he knows anything about writing code for flight control systems in commercial environments. Maybe he's written some toy code in MATLAB demonstrating some things, that's never undergone testing on a real airframe.

Are there any airliners for which a sustained 60-70 degree angle of attack over a span of several minutes is not overwhelmingly likely due to sensor failure?

I think it's fair to say that his knowledge of aircraft plus his knowledge of software and electrical engineering qualify him to speculate.

Its quite likely he has greater knowledge of both subjects than the person who physically implemented MCAS.

Sadly, no speculation is necessary. Had that change been included in MCAS the Ethiopian crash wouldn't have happened.

However, any programmer that's been around the block a few times knows when they see a phrase like

"all of the problems on the Ethiopian flight could potentially have been avoided by changing....about 10 characters of code"

It's a sign that things are never as simple as they seem on the surface.

Down by 4 at the Super Bowl, 2nd & Goal, 27 seconds on the play clock, Lynch in the back field.

  Run the ball

About 10 characters of code. Sometimes armchair quarterbacking has a point.

As a Hawks fan, that hurt. Really hurt.

The agony: https://www.youtube.com/watch?v=U7rPIg7ZNQ8

Even there though, the fact that the Pats scout team ran that exact play twice in practice with the backup nickelback in was something that the coach perhaps could not have anticipated?

Any result other than an INT means Lynch still has a chance to run.

Philip Greenspun is not a no one when it comes to aviation.

https://philip.greenspun.com/flying/resume

While he doesn't have 737 experience, he's far from an armchair quarterback.

Do you think the analysis is invalid?

Do you think that an autopilot response to "AOA > 15 degrees" should be the same regardless of whether AOA is 20, 40, 60, or 80 degrees?

Is there an industrial coding standard that makes recommendations here?

What does NASA do?

a common practice is to limit the number of bits in the data value which will limit the range of values it can have

This type of elitism has no real place in hopefully constructive conversation.

I'm not going to ignore a well thought out point because someone doesn't have a PhD in the exact question under rumination.

And "armchair quarterbacking" tends to translate to "Request For Comment" in my book. I.e. a coming together of disparate ideas and areas of expertise to more fully render the extent of a problem.

This seems equivalent to "it is just a button, how hard can it be?" People outside of software rarely see the complexity they are suggesting or asking for.

Philip Greenspun is, in fact a pilot. He is not a 737 pilot, but probably has a better idea of how a 737 works than the average HN armchair quarterback.

philg's been flying and writing about it for years: https://philip.greenspun.com/flying/

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