Philip Greenspun’s Weblog

“What the Lion Air Pilots May Have Needed to Do to Avoid a Crash” (nytimes) contains a lot of good cockpit photos and illustrations explaining the combination of manual and automatic flight controls that likely played a role in the recent Boeing 787 MAX 8 crash (see https://philip.greenspun.com/blog/2018/11/11/boeing-737-crash-is-first-mass-killing-by-software/ ).

If it sensed a stall, the system would have automatically pushed up the forward edge of the stabilizers, the larger of the horizontal surfaces on the plane’s tail section, in order to put downward pressure on the nose.

To counter the nose-down movement, the pilot’s natural reaction would probably have been to use his yoke, which moves the other, smaller surfaces on the plane’s tail, the elevators. But trying that maneuver might well have wasted precious time without solving the problem because the downward force on the nose exerted by the stabilizer is greater than the opposite force the pilot would be trying to exert through the elevator, said Pat Anderson, a professor of aerospace engineering at Embry Riddle.

“After a period of time, the elevator is going to lose, and the stabilizer is going to win,” he said.

(The same guy gave an interesting lecture this summer; see “Transitioning to electric flight (lectures at Oshkosh)”.)

The pictures show a mix of 1950s (the big trim wheel), 1980s (the switch-controlled trim and trim interrupt), and 1990s (the MCAS layered on top that puts in heavy trim silently).

My comment on the NYT piece:

I sometimes fly the Pilatus PC-12, a simple 11-seat turboprop. Its stall-protection system was designed in the early 1990s. There are two angle-of-attack (AOA) sensors, one on each wing. There are two computers, each one of which is connected to a single AOA sensor. Only if both AOA sensors show a stalling angle of attack (“nose too high”) AND both computers agree THEN there will be a “stick push”. Thus there could never be a nose-down push due to a single bad AOA sensor. In the unlikely event that both sensors and/or computers went haywire at the same time, there is a “pusher interrupt” switch right on the yoke (“stick”). So the pilot need not hunt for an out-of-sight and never-previously-used switch.

It sounds as though Boeing engineered something that relies on just one sensor.

Plainly the Pilatus-style system would not have interfered with these 189 souls making their way safely to the destination. I wonder if a simple voice annunicator on top of the Boeing system would have also saved the passengers and crew. If it had said “trimming down, trimming down” into the headsets, the pilots would have known to direct their attention to the trim and trim interrupt switches.

“7 Women Accuse Dartmouth Professors of Sexual Abuse in Lawsuit” (nytimes):

Seven women are suing Dartmouth College for sexual assault, harassment and discrimination they say they experienced from three prominent professors who, according to the suit, turned a human behavior research department “into a 21st-century Animal House.”

For over a decade, the professors — Todd Heatherton, William Kelley and Paul Whalen — “leered at, groped, sexted, intoxicated and even raped female students,” according to the court papers, which were filed Thursday in federal court in New Hampshire.

The lawsuit, which seeks $70 million in damages…

There are approximately 4,300 undergraduates at Dartmouth. In-state tuition at University of New Hampshire is $18,500 per year (source). At rack rates, therefore, 4,300 students would pay $79.5 million at UNH. Assuming only a modest amount of financial aid, then, it would cost less to send all 4,300 of these undergrads to UNH than the amount of damages that was inflicted on these seven women.

I’m wondering if the Amazon HQ2 deals show how to implement a planned economy without having to acknowledge that one’s country has transitioned away from the market.

Planned Economy v1.0: It is illegal for anyone to operate a business without approval from a government ministry. Government experts decide which companies can operate, from which locations, and engaging in which businesses.

Planned Economy v2.0: Set up tax rates that are, by global standards, punishingly high. It is therefore impractical to do business if a company must pay the headline rates. Government experts decide that certain companies, in certain locations, and engaging in certain activities, can operate with tax rates that are closer to global norms.

We’re not quite to this point, but with a few upward tweaks of the tax rates I think that we could be.

Related:

• “A $2 Billion Question: Did New York and Virginia Overpay for Amazon?” (nytimes): “An additional $7.5 billion in subsidies wasn’t enough to get Amazon to move across the river,” said Michael Farren, an economist at the Mercatus Center, a libertarian think tank, referring to the difference between Maryland’s offer of $8.5 billion and Virginia’s of less than $1 billion. “That just says that subsidies were never what mattered in the first place.” (the Maryland location would have been awesome for family court plaintiffs suing Amazon employees! See Real World Divorce for what is obtainable.)
• “Helipads and everything else Amazon is getting out of its deals with New York and Virginia” (CNN). This has been a good month for Airbus (Eurocopter)!