Another airplane that fights the pilot if one AOA sensor is bad: Cirrus Jet

In another triumph for American engineering, it seems that the Cirrus Jet‘s stick pusher activates if a single AOA sensor fails mechanically (FAA Emergency Airworthiness Directive 2019-08-51). The system isn’t quite as badly designed as the Boeing 737 MAX’s silent gradual pusher, but it is nowhere near as robust as the early 1990s design on the Pilatus PC-12 (Swiss engineering). An important difference is that it is obvious to the pilot(s) when the Cirrus system is operating and the disconnect button is right on the yoke (just the usual A/P disconnect button).

Full post, including comments

Reasonable to blame right-seat Labradoodle for the go-around accident?

A two-seat light sport plane crashes near the runway while a 13-knot wind is blowing. The 90-year-old pilot is killed. Who is to blame? Jasmine, the right-seat Labradoodle, according to the NTSB report. The probable cause:

The pilot’s decision to fly with his large dog in the two-seat, light sport airplane, and the dog’s likely contact with the flight controls during landing, which resulted in the pilot’s loss of airplane control and a subsequent aerodynamic stall when the airplane exceeded its critical angle of attack.

Without a cockpit video recorder, how exactly do we know this?

A witness, who was piloting another airplane in the traffic pattern, reported that, while he was on the downwind leg, he saw the accident airplane on final approach to the runway.

Based on available ground track and engine data, the airplane crossed the runway 27 threshold at a calculated airspeed of 48 knots. About 3 seconds later, the airplane turned right away from the runway heading, and the engine speed increased to takeoff power.

Given the ground track and engine data, it is likely that the dog contacted the aileron and/or stabilator controls during landing, which resulted in the pilot’s loss of airplane control and a subsequent aerodynamic stall at a low altitude when the airplane exceeded its critical angle of attack.

Does it make sense to blame Jasmine? She was manipulating the flight controls? Maybe. But wouldn’t a Labradoodle be more likely to push nose-down rather than grab the yoke with her teeth and pull nose-up? And the Labradoodle was also responsible for initiating a go-around by adding full throttle?

(Separately, as is typical with car accidents that kill humans, the supposedly inferior canine more or less walked away:

After the accident, the witness saw the pilot’s dog, who had been onboard the airplane, running out of the cornfield where the airplane had crashed. First responders were able to catch the dog, who was treated for minor injuries by a local veterinarian.



Full post, including comments

Aircraft types that I have flown

I was asked to fill out a form showing the aircraft that I have flown and it turned out to be a longer list than expected…

  1. 8KAB (Decathlon)
  2. AA5 (Grumman Tiger)
  3. AC95 (Twin Commander 1000 turboprop)
  4. B200 (King Air 200 turboprop)
  5. B206
  6. B505 (new Jet Ranger)
  7. BE36
  8. BE55
  9. BE58
  10. BE103 (Beriev twin-engine seaplane!)
  11. C172
  12. C182
  13. C210 (in southern Africa)
  14. C310 (crazy noisy!)
  15. C510 (Cessna Mustang jet)
  16. CJ3
  17. CL65 (Canadair Regional Jet)
  18. COL4 (Columbia 400/Cessna 400)
  19. DA20 (Diamond Katana)
  20. DA40 (Diamond Star)
  21. EMB-500 (Phenom 100 jet)
  22. Evolution (experimental turboprop)
  23. Gamebird GB1
  24. HK36 (motor glider)
  25. M20T (turbocharged Mooney)
  26. PA12 (Piper Super Cruiser… on floats!)
  27. PA28
  28. PA32
  29. PA34
  30. PA38 (with a very slender student!)
  31. PA44
  32. PA46 (Malibu; the dream family airplane as long as one can get a letter from God promising that the engine won’t quit)
  33. PC12
  34. R22
  35. R44
  36. R66
  37. SGS 2-32 (glider)
  38. SGS 2-33 (glider)
  39. SR20
  40. SR22
  41. TBM850

Adding to this blog so that the information doesn’t get lost. I was thinking that it would be good to put the favorites in bold, but I realized that at least half of the above aircraft would need to be marked. Most of them have at least some great characteristics.

The list would be a bit longer if I included variants, e.g., the turboprop versions of the PA46, the retractable version of the PA28, or the turbocharged version of the SR22.

Despite FAA English proficiency requirements for certificate holders, I am having some trouble understanding this new copilot. I think that he is complaining about the lack of A/C in the Cirrus:

Full post, including comments

Sultan of Brunei owns Piper Aircraft

“Piper’s financial ties to anti-gay Brunei stir up controversy, with Harris caught in crossfire” (Florida Today):

Vero Beach-based Piper Aircraft Inc. has become embroiled in an international controversy, as a result of its ownership by the government of Brunei, which has just implemented a harsh new law that punishes sex between men and adultery with death by stoning.

Jackie Carlon, senior director of marketing and communications for Piper, said that, while “the shareholder of Piper Aircraft is the ministry of finance of Kingdom of Brunei,” and “we’re very, very aware of” the policy in Brunei, “I can’t control what they do in their country.”

Carlon said Brunei currently doesn’t profit from Piper’s business, but rather reinvests the profits back into the company.

I.e., so far this has been a money-sink for the Sultan. Surprise, surprise! (Who told him that general aviation would be a good investment? That Piper had already gone bankrupt twice in its history so plainly a third bankruptcy was impossible?)

Cirrus, the market leader in family-sized aircraft, was formerly owned by the First Islamic Investment Bank, ultimately renamed Arcapita, “the premier source for Shari’ah-compliant alternative investments” and “a global leader in Islamically acceptable alternative investments.” It is unclear if Arcapita maintained traditional Islamic views regarding sexual activities. Cirrus today is owned by the Chinese government, basically, and China does not comply with U.S. standards regarding, for example, same-sex marriage (Wikipedia).

Maybe the answer is to pay up for an Embraer Phenom 300? The company is Brazilian, part-owned by the Brazilian government, and same-sex marriage is available in Brazil (Wikipedia). If you’re passionate about flying and matters LGBTQIA, but approximately $10 million short of the $10 million necessary for a Phenom 300, Cessna is owned by Textron, which earned a perfect score in the 2019 Corporate Equality Index (“Rating Workplaces on Lesbian, Gay, Bisexual, Transgender, and Queer Equality”). New and used Cessnas are available to suit nearly every budget.

Full post, including comments

Boeing 737 MAX crash and the rejection of ridiculous data

“Boeing 737 Max: What went wrong?” (BBC) contains a plot showing the angle of attack data being fed to Boeing’s MCAS software. Less than one minute into the flight, the left sensor spikes to an absurd roughly 70-degree angle of attack. Given the weight of an airliner, the abruptness of the change was impossible due to inertia. But to have avoided killing everyone on board, the software would not have needed a “how fast is this changing?” capability. It would simply have needed a few extra characters in an IF statement. Had the systems engineers and programmers checked Wikipedia, for example, (or maybe even their own web site) they would have learned that “The critical or stalling angle of attack is typically around 15° – 20° for many airfoils.” Beyond 25 degrees, therefore, it is either sensor error or the plane is stalling/spinning and something more than a slow trim is going to be required.

So, even without checking the left and right AOA sensors against each other (what previous and conventional stick pusher designs have done), all of the problems on the Ethiopian flight could potentially have been avoided by changing




About 10 characters of code, in other words. (See the Related links below for the rest of the flaws in the MCAS system design, which the above tweak would not have fixed.)

We fret about average humans being replaced by robots, but consider the Phoenix resident who sees that the outdoor thermometer is reading 452 degrees F on a June afternoon. Will the human say “Arizona does get hot in the summer so I’m not going to take my book outside for fear that it will burst into flames”? Or “I think I need to buy a new outdoor thermometer”?


Full post, including comments

Cheaper planes for fatter Americans

Thirty years ago, 85 percent of students and instructors could conduct training in a two-seat airplane. Today, 85 percent of students and instructors need to use a four-seat airframe. It would be inconceivable for four typical GA-interested American adults to take off within safe weight & balance limits for the typical 1950s or 1960s-designed airframe.

Cirrus responded to the changed circumstances by making the SR22, a four-seater with 1,000 lbs. more gross weight and twice the horsepower compared to a 1960s four-seater.

Piper has done something interesting. They’ve taken a seat out of their four-seater (1960 design), put in an experimental glass panel, and delivered a new IFR-capable three-seat airplane, including the fantastic Garmin GFC 500 autopilot, for $285,000 (down from more than $370,000; compare to a Cirrus SR20 at $455,000 before options). And it probably will be able to take off with three adult Americans circa 2020!

One issue: the airplane will be called the “Pilot 100”. Did the marketing staff at Piper recently come over from Dorco USA?

See this article from Plane&Pilot.

One unusual twist is using a 180-horsepower engine from Continental, now under Chinese ownership. Industry experts say that Lycoming makes a more reliable engine, especially the IO-360 Lycoming. Also that Lycoming support is far superior. Cirrus recently dropped Continental as a supplier for its lower-powered model, the SR20.

(Out of a handful of SR22s in our T hangars, the premature failure rate on the bigger Continental engines has been high. One failed catastrophically at 300 hours. Another failed at about 900 hours (supposed to last 2,200) and one month after its three-year warranty expired. Continental refused to do anything for the customer other than sell him a new engine at the standard price.)

Full post, including comments

Transgender solution to the Boeing 737 MAX problem

How to handle the public relations challenge of operating a new two-pilot two-jet-engine airliner with a safety record far worse than that of a 50-year-old single-pilot piston-engine plane such as the Cessna 402 (when used in airline service)? United Airlines seems to have found a way. From a friend on Facebook:

I ❤️ #United #LGBTQ #nonbinary

(Over a link to “United Becomes First U.S. Airline To Offer Nonbinary Gender Booking Options”)

What did the database programmers at United accomplish?

The U.S. airline will offer multiple gender options for customers booking flights, including M (male), F (female), U (undisclosed) and X (unspecified). United added that the title “Mx.” also will be available for travellers to select.

The gender option chosen by the passenger must correspond “with what is indicated on their passports or identification” in order to satisfy the Transportation Security Administration, United said. Anyone regardless of identification can choose the title “Mx.”

For whom can this work as a practical option, then?

More and more states have added gender options on identification. Oregon, California, Arkansas and Washington state currently offer a third gender option on birth certificates, while Washington, D.C., offers a third gender option on driver’s licenses. Most recently, the New York City Council announced it will offer “X” as a gender category for people who don’t identify as female or male.

What about for international travel? The U.S. Department of State offers a helpful page for those transitioning from one officially recognized “sex” to another. On the other hand, it seems that male/female are the only options. From “Victory! State Department Cannot Rely on its Binary-Only Gender Policy to Deny Passport to Nonbinary Intersex Citizen”:

The State Department denied Dana’s passport application because Dana could not accurately choose either male or female on the passport application form, and the form does not provide any other gender marker designation.

This is the second time Zzyym has won against the U.S. State Department for denying them a passport. In November, 2016, the same district court found the State Department had violated the federal Administrative Procedure Act and ordered the department to reconsider its binary-only gender policy.

The State Department doubled-down on its discriminatory male-or-female-only policy to deny Zzyym a passport, leading to today’s ruling.

So the nonbinary traveler making a domestic connection before an international flight would need a reservation with two genders: X for the domestic leg to correspond to the driver’s license and M or F for the international leg to correspond to the passport.

Backing up a bit… if the airline’s record must correspond to the gender stated on the passenger’s ID, did United have any choice but to task its database programmers with this project? Wouldn’t every airline have to invest in updating its systems to the modern world of gender-on-a-spectrum if the governments issuing IDs are changing their policies? So the PR folks at United are possibly even more brilliant for getting positive press for an expensive IT project that they were forced into doing.


Full post, including comments

Optional Angle-of-Attack Sensors on the Boeing 737 MAX

“Doomed Boeing Jets Lacked 2 Safety Features That Company Sold Only as Extras” (nytimes):

Boeing’s optional safety features, in part, could have helped the pilots detect any erroneous readings. One of the optional upgrades, the angle of attack indicator, displays the readings of the two [angle of attack] sensors. The other, called a disagree light, is activated if those sensors are at odds with one another.

Boeing declined to disclose the full menu of safety features it offers as options on the 737 Max, or how much they cost.

When it was rolled out, MCAS took readings from only one sensor on any given flight, leaving the system vulnerable to a single point of failure. One theory in the Lion Air crash is that MCAS was receiving faulty data from one of the sensors, prompting an unrecoverable nose dive.

[Watch the Aerodynamics lecture from our MIT FAA Ground School to learn more about angle of attack.]

As I noted in a previous posting, the Pilatus PC-12, a much cheaper and simpler airplane (1 engine and 9 passenger seats), doesn’t do any nose-down pushing unless two separate angle-of-attack sensors, and their respective computers, agree. Boeing’s ideas of

  • a system that works silently (so pilots don’t realize it is operating)
  • a system that works if just one sensor suggests a high angle of attack
  • a system that has the authority to drive the airplane into a full nose-down trim situation
  • a Band-Aid on the above in the form of a “disagree” warning light

are all terrible ones, as far as I can tell, and unconventional within the industry.

Does that mean we need much more stringent oversight by regulators? (as noted in this other previous posting, the “regulators” in the case of the above system were mostly Boeing employees) Maybe.

The prices of these optional items that would have made Boeing’s unsafe design a little less unsafe were too shocking for Boeing to admit or the NY Times to publish. But reasonably high-quality systems for homebuilt 2-seat and 4-seat airplanes are less than $2,000, including both the sensor and indicator. Examples:

So it is tough to know whether regulation should have been relaxed so that Boeing’s costs of putting reasonably modern avionics into the airplane were reduced or toughened so that the crazy bad ideas were squashed. (Or, as my previous posting suggests, shifted so that an independent private engineering service would do the steps that Boeing’s employees were doing while nominally wearing FAA hats.)

Full post, including comments

The aviator with songs stuck in his head

Participants at a local gathering of pilots were required to tell a joke. Here’s what I said…

I don’t want to tell a joke because so many people in this world are suffering with serious problems, like [FAA non-essential air traffic control employee, previous speaker] who talked about his personal struggles in Arizona and Europe during the paid 35-day shutdown.

I’m teaching computer programming this month at Harvard Medical School. One of the residents talked about a recent case that he observed.

A pilot came into the hospital and said “When I’m on final at 6B6 I can’t get the song ‘The green green grass of home’ out of my head. If I see a Grumman Cheetah on the tie-downs then it’s ‘What’s new, pussy cat?’. It’s distracting me from my approaches and preflights.

The attending physician said, “I’m pretty sure that you’re in the early stages of Tom Jones syndrome. Unfortunately, 72.3 percent of the time the disease is progressive and incurable.”

“72.3 percent?!? How have you seen enough cases to give a precise number like that? I’ve never heard of Tom Jones syndrome so I assume it is quite rare.”

The doctor thought for a moment. “Well, it’s not unusual.”

Full post, including comments

Could the Boeing 737 MAX be flown safely with a robot dome light third pilot?

Unfortunately, we now know that a two-pilot crew cannot safely handle the silent gradual pusher system of the Boeing 737 MAX.

“Pilot Who Hitched a Ride Saved Lion Air 737 Day Before Deadly Crash” (Bloomberg) says that a three-pilot crew was able to handle the design deficiencies in Boeing’s silent gradual pusher system. (The third pilot was in one of the comfy jump seats; I enjoyed a ride once in a B757 jump seat and it is remarkably luxurious.)

One of the ideas that I’ve been in love with for years is a robot copilot up in the dome light that can see everything the pilots see and, without anyone having to certify modifications to the legacy systems, help out with suggestions in the intercom. In the case of the 737 MAX, for example, the dome light copilot could notice when the runaway-trim-by-design system is operating and suggest “hit the trim interrupt switches!”

(Alternatively, of course, the Boeings could be returned to service with the requirement that they be flown by three pilots in the cockpit at all times, like a World War II bomber or Boeing 727. (In the not-so-good old days, a heavy airplane would have two pilots to manage the flight controls, a flight engineer (i.e., a third pilot) to manage the systems, and a navigator to watch the position over relative to the ground.))


Full post, including comments