Category: Flying

Stories about flying planes and helicopters, discussions of technique and teaching.

Boeing 737 crash is first mass killing by software?

by philg

The Lion Air 610 mystery/tragedy seems to be mostly solved. The Boeing 737 MAX 8 airplane, which uses a de Havilland Comet (1949; also BBC)-style hydro-mechanical flight control system, has a touch of intelligent software layered on top. This NYT article and an Emergency Airworthiness Directive #2018-23-51 explain how the airplane will trim itself into a crazy nose-down attitude in the event of a single angle-of-attack (AOA) sensor going bad.

“At Doomed Flight’s Helm, Pilots May Have Been Overwhelmed in Seconds” (nytimes) explains 

[disabling the system] would not have been a simple matter of pushing a button. Instead, pilots said, Captain Suneja could have braced his feet on the dashboard and yanked the yoke, or control wheel, back with all his strength. Or he could have undertaken a four-step process to shut off power to electric motors in the aircraft’s tail that were wrongly causing the plane’s nose to pitch downward.

Can we consider this the first mass killing by software?

[Background: an airplane wing will suffer an aerodynamic stall, in which the airflow over the top of the wing is no longer smooth, and lose Bernoulli effect lift, if the angle between the relative wind and the wing is too large. This is what limits an airplane’s ability to hover. To generate sufficient lift, the wing has to be within about 12 degrees of level and the wing needs to keep moving. It isn’t possible to fly super slowly at a 45-degree nose-up angle and still have enough lift to remain at the same altitude. The helicopter works by spinning a conventional airfoil so that, even if the fuselage isn’t moving, the wing is still moving rapidly and generating lift.]

What are some alternatives to Boeing’s design, you might ask? The Airbus philosophy, as embodied in the A320 and subsequent airliners, is to turn everything over to the computer(s). Despite holding the stick all the way back, Captain Sully was not able to stall the A320 that landed in the Hudson River. If the fancy computers on an Airbus aren’t getting what they think is good or consistent data from the various sensors, they hand over the machine to the pilot who can look out the window or at the attitude indicators in the cockpit and do something sensible (or panic like a student pilot, as with Air France 447).

Stepping down the food chain, we have the Pilatus PC-12, a Swiss-designed 11-seat turboprop. The plane starts out with a standard light aircraft flight control system. The pilots’ yokes are connected directly to control surfaces via pushrods and cables. On top of this Pilatus has layered a stick shaker to warn pilots that the airplane is nearing a stall and a stick pusher that yanks the yoke forward. The airplane has a great safety record despite being operated into some challenging short runways and being flown, in some cases, by inexperienced pilots.

Instead of Boeing’s single AOA sensor and software to run the trim, the PC-12 has two AOA sensors and two computers. If both sides agree that it is time to go nose-down, then and only then will the stick pusher be engaged. If somehow both sensors and both computers are defective and push inappropriately, a “pusher interrupt” button is always right there on each yoke. From the AFM (“owner’s manual”):

A friend who is a Silicon Valley engineer texted me incredulously “Wouldn’t they do fusion from zillions of sensors?” My response on the FAA certification process:

It is like ISO 9000. Boeing had binders of paperwork and bureaucratic approval for their design, but the design itself may never be scrutinized.

Almost certainly if the B737 had the same system design as the PC-12 all 189 folks aboard Lion Air 610 would have arrived safely at their destination. The worst that would have happened is the pilots being briefly annoyed by a shaking stick and having to hit a checklist.

I’m not sure if this crash can fairly be attributed to a software problem, since the software presumably did function as designed. It seems that we can attribute the crash to a poor system design, but ultimately the plane was crashed into the water by software.

Related:

  • Wikipedia has a good article on the various aircraft flight control system alternatives
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ADS-B should sequence airplanes at nontowered airports?

by philg

I flew the Cirrus recently to Gaithersburg, an airport that supposedly sees only 131 operations per day (airnav). On the flight from Allentown, Pennsylvania to KGAI, the controllers did not even once tell me to look for a nearby plane. I was pretty much alone in the sky at 6,000′.

Things were different within 5 miles of the destination airport. I arrived on a gusty bumpy Tuesday at 1 pm and became the fourth airplane in the pattern as this non-towered airport. I departed behind a Pilatus PC-12. The Pilatus crew waited for a small plane to land before they could depart. I asked a plane on downwind to extend slightly so that I could get out with my IFR clearance (i.e., there were at least four airplanes operating at 5 pm when I departed). Given the active flight school at KGAI and the fact that I have nearly always found myself with company in the traffic pattern there, I question the 131/day number (since there is no control tower, the statistic may not be authoritative).

There is some structure to the traffic pattern at an airport that makes it a bit easier for pilots to identify each other, but self-sequencing is not always successful. AOPA’s Air Safety Institute: “Eighty percent of the midair collisions that occurred during ‘normal’ [not formation or aerobatics] flight activities happened within ten miles of an airport, and 78 percent of the midair collisions that occurred around the traffic pattern happened at nontowered airports.”

Americans have spent billions of dollars over the last twenty years on ADS-B, partly sold as a way to avoid midair collisions. I’m wondering now, though, if ADS-B solves the wrong problem and/or the non-problem of enroute traffic conflicts.

Maybe it was too advanced an idea in the 1990s when ADS-B was conceived (with an implementation date of Jan 1, 2020!), but I wonder if it would make sense for ADS-B gear to sequence airplanes at nontowered airports. Why couldn’t the pilot press a button on the transponder and have the ADS-B software say “You are Number 3 for Runway 32. Number 2 is turning right base. Number 1 is on final”?

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Ideas for flying around New England

by philg

A Swiss surgeon recently came to Boston for a conference. East Coast Aero Club prices are 1/3 to 1/2 what it costs to rent a plane in Switzerland so he decided to spend a week before the conference flying the Cirrus SR20 3-4 hours each day, with periodic cigarette breaks (regrettably the Cirrus is placarded against smoking, thus rendering it less than ideal for a European physician; in the good old days, four-seat GA planes had ashtrays!).

I thought I would share the set of proposed flights in case it is useful to others.

Readers: Let me know if you have other/better ideas!

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Time to plan the Bahamas and Caribbean trip with new AOPA guides

by philg

I think it is time to plan a new Bahamas/Caribbean trip. The last one was in 2003 in a Diamond DA-40 (write-up). Back then I wrote “The bible of Caribbean flying is the Bahamas & Caribbean Pilot’s Guide by John and Betty Obradovich.” This has been taken over by AOPA and split into two hardcopy books ($80/year for the latest versions) and/or two apps ($80/year for updates). They try to get the new versions out on October 15 of each year.

The guides are good on the basic stuff that you’d find in the FAA Chart Supplement (AF/D): runway length, fuel availability, phone numbers. They add information on nearby hotels, restaurants, and activities, plus some overview information on each island. They’re weak on some critical details for planning stops, e.g., what does it actually cost to stop for two nights in a light single-engine plane? Phone numbers are included, but not the email addresses that a pilot trying to plan would likely prefer. As with a lot of other resources in aviation, the guides assume that you already know what you need to know, i.e., that you’ve already decided which airports to visit. If you know that you want to fly the island chain, but aren’t sure where to stop and don’t have time to make dozens of phone calls, it might be better to let an experienced handler such as Air Journey plan the trip ($795) because they’ll know which airports/countries not to stop in. (See “Is it possible to build an app whose job is to use another app?” for how ForeFlight and Garmin Pilot have the same issue.)

[Wishlist for the guides: (1) fee grid for every airport showing quickturn and 2-night stop all-in fees for light singles, light twins, and single-engine turboprop, (2) a section with suggested itineraries for people who don’t know where they want to go. The suggested itineraries would include airports with reasonable fees and nearby pleasant hotels and/or attractions.]

BeechTalk seems to be a great resource for trip planning. Folks there have done everything. I posted a question about an Eastern Caribbean trip and got back a lot of helpful information, the most inspiring of which was this 2018 tale (unfolding in the replies over 6 pages) of flying a Columbia 400 from Texas to Argentina.

[My initial idea for a trip:

Turks and Caicos may get scratched due to $300 in fees for an overnight (or a lot more if on a weekend of after hours!). The 100LL price at MBPV is quite reasonable, though.]

I thought that it would be fun to stop on the way back in Cap Haitien. The AOPA guide says “cattle and people have unrestricted access to the airport”. From a Pilatus pilot: “I have 18 landings in Haiti. In my opinion, going to Cap Haitien would be stupid, very stupid. There is no security for your plane, and not much to see. I’d rather be out of Haiti thinking about going to Haiti, than be in Haiti, worrying about getting out. If you really need Haiti in your logbook, I would consider Jacmel, but I wouldn’t go there either. As I was told before my first flight there ‘Remember that Haiti’s business is poverty’. The last time I was there, I did a short field takeoff on departure [from a super long runway] to get the F### out of there!”

The Caribbean is one of those places where it vaguely does make sense to fly yourself around in a light airplane. There are no highways linking the desired stops!

Related:

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Private Pilot Ground School at MIT in January

by philg

If you’d like to learn what pilots learn, and enjoy the bracing air of a Boston winter, join us in January for MIT Course 16.687. The dates are Jan 22-24, 2019 and it is all-day every-day.

Details: http://philip.greenspun.com/teaching/ground-school/

This is a for-credit class for MIT students, but it is free to non-MITers.

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General aviation accident rate flat for a decade despite fancier technology

by philg

The 27th Nall Report, analyzing aircraft accidents in 2015, was recently published by AOPA Air Safety Institute. The publisher says “Imagine a year without a single fatal accident in GA [general aviation]. We aren’t there yet, but we’re getting closer every year.” The data plotted on page 6, however, show that the accident rate and fatal accident rate are essentially flat from 2006 through 2015. During that time the fleet has seen a lot of technological upgrades. Old Cessnas and Pipers have been retired in favor of some of the thousands of parachute-equipped glass-panel Cirruses produced during those 9 years. Datalink weather (XM or ADS-B) has been added to a lot of planes. Retrofit glass panels. Synthetic vision (a flight simulator-style view of the terrain out the window).

The fatal accident rate for GA non-commercial (Joe Average flying around in a Cessna or Cirrus) went from 1.22 per 100,000 hours to 1.13 between 2006 and 2015 (fixed-wing commercial was a lot better! Only 0.24 and that includes dangerous agricultural work as well as safe two-pilot charter work.)

It might be a statistical fluke, but the fatal accident rate for non-commercial helicopter operations was down to 0.57, well below that of fixed wing and barely higher than the rate for commercial helicopters (0.45 per 100,000 hours).

My take-away: we need radical change if we want to see radical improvement. Maybe it is “Ground Monitoring for Part 91 Operations”. Maybe it is aggressive envelope protection for existing flight control systems (see “Could the latest autopilots with envelope protection turn a deathtrap into a safe airplane?“). Maybe it is a retrofit fly-by-wire flightpath-based flight control system (see the U.S. Navy’s MAGIC CARPET system for landing the F/A-18).

Readers: What do you think? Would you have expected more from the improvements that have been introduced in the last 20 years?

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Experiments with a new camera mount system for aircraft

by philg

One of the best things that I saw at Oshkosh was Flight Flix, a vibration-isolation system for mounting an action camera on an airplane or helicopter. I purchased mounts for the Cirrus SR20’s tie-down ring and the tow ball underneath the R44 and have begun testing these with the Drift action camera that the company favors due to its long battery life and easily rotated lens for proper “horizon up” orientation. I’m wondering if readers can help with critiques on a couple of tests from the SR20 under-wing mount:

Which one seems better? (“better” = “more stable”) Thanks in advance!

(It was a slightly challenging day for a “stable video” test, with winds gusting up to 18 knots and bumpy air through about 3,000′.)

Dream #1 is to get footage from a $199/hour airplane that looks as good as footage from a $199 drone. Dream #2 will be to get footage from a $369/hour helicopter that looks as good as footage from a $369 drone!

[So far I am not loving the Drift camera. The connection between the camera and the Drift app on an iPhone X is tenuous and I have found it tough to make the settings stick or even start and stop the camera reliably. By contrast, the integration between a phone and the DJI Osmo camera is so tight that feels like using a regular camera’s electronic viewfinder. Support from Flight Flix has been excellent, on the other hand, and they seem to have thought of almost everything. Flight Flix has produced some inspiring sample videos with the Drift, so I know that it can be done even if not by me! And the four-hour battery life (Wi-Fi off; bigger battery option) seems realistic.]

One thing that strikes me as odd is that airframe manufacturers haven’t added mounts for action cameras, both inside and outside, on their latest versions. Wouldn’t most people who spend $800,000+ on a new Cirrus want the option of making a recording without hanging something off a tie-down ring?

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Oshkosh Reflections and Tips for Next Time

by philg

EAA’s AirVenture (“Oshkosh”) was packed in 2018, no mean feat in what is supposedly a dying industry. Airplane parking at KOSH and general aviation camping were both full by Monday afternoon, the first official day of the event (a lot of folks arrive early).

My companions laughed at me for making an IFR reservation for our arrival. After we landed we heard about people who had been forced to hold for literally hours trying to get in on Saturday or Sunday (a lot of marginal VFR weather resulted in bottlenecks). IFR reservations via STMP aren’t that tough to get, even same-day, due to the fact that people make them and don’t confirm. We went out IFR as well.

If flying in and camping, my advice would be to arrive Wednesday evening or Thursday morning. By then a lot of campers have departed and some prime spots become available. You would still have four full days to enjoy the event. Make sure not to miss the night airshow, which is Wednesday and Saturday evenings. We were awed by Nathan Hammond doing aerobatics in an LED-festooned fireworks-launching Super Chipmunk. Like Burning Man, but without the dust storms!

One question that we couldn’t answer from EAA’s web site was “How do we park a car if we’re airplane camping at Oshkosh?” A friend drove in from Chicago and met us in our tent site. It turned out that the folks collecting the money for our camp site asked “Do you need a parking space for a car?” and for $10/day we got one right next to the beginning of the North 40. This was helpful for escaping “show food” at Manila and Gardina’s. It was also a pleasant way to get to the seaplane base.

We met several people who’d had mobile phones stolen from the charging stations distributed around the camp sites. The smart folks (i.e., not us) arrived with portable phone chargers so that they could charge a battery and keep their phones with them. Another dumb thing that we did was bring our own payload-robbing tie-down kit. EAA rents far better ones for use at the show for $20 ($30 minus $10 when returned). (The tie-down guys will also graciously let you charge a phone inside their shack, secure from the roving thieves!)

EAA does a remarkable job of keeping traffic moving during the show. Nonetheless, given the vagaries of flying in and the hassles of getting to and from the show by private car, I think the most sensible approach might be to stay in a University of Wisconsin, Oshkosh dorm room and catch the bus or an Uber to the center of EAA. Given that there are nonstop flights from everywhere in the U.S. to Chicago, it is a 2.5-hour drive from O’Hare Airport, and it is kind of nice to have a car at Oshkosh, there is no great argument to be made for flying in unless you’ve got an unusual plane to show off (our Avidyne-equipped Cirrus turns out to be one of 4,000 built!).

We paid up for the EAA Aviators Club (about $135 per day), which serves meals in an air-conditioned super-tent. We figured that it would be a necessary escape from the 95-degree heat and the crush of show crowds. 2018 turned out to be a relatively cool and comfortable year, however, and we got sick of the club buffet food pretty quickly. It was noisy inside the tent and it wasn’t difficult to get equally good seats for the airshow (if you were willing to carry folding chairs!). The owners’ lounge that Cirrus ran within its pavilion was actually a much better place to chill out, though it had no view of the flight line. On the third hand, it was nice to be able to charge our phones at the Aviators Club without worrying about having them stolen! And it was a convenient place to meet, pick up a cold seltzer, etc.

Interesting destinations we learned about…

  • National WASP Museum in Sweetwater, Texas (unfortunately no parking on their ramp; why can’t there be more fly-in museums?)
  • Dakota Territory Air Museum in Minot, North Dakota (some interesting warbirds that rotate through, plus a large permanent collection)

Interesting products that we saw…

  • aural angle of attack project
  • Flight Flix camera mounts. The example videos are impressively stable. The isolation is provided via an elastomer mount.
  • Nulite ring lights that replace the hideous and uneven post lights in steam gauge aircraft such as Pipers and Robinsons (though I’m sure that Robinson would rip them right back out during a factory overhaul!)
  • Dynon D3 Pocket Panel ($995 glass panel that does nearly everything that a $50,000 Garmin option package on a VFR-only Robinson R44 will do, and with essentially equivalent safety or that a $350,000 retrofit King AeroVue glass cockpit does in a King Air)

If the success of EAA AirVenture proves that general aviation isn’t dead, the pace of innovations for products on display proves that the general aviation industry is more or less dead. BendixKing is a great example of corporate suicide. They have an enormous installed base of transponders. Do they make a plug-compatible ADS-B IN/OUT replacement? No. They make a transponder that is ADS-B OUT only. So all of their customers are getting avionics shops to rewire for the Garmin 345. Why couldn’t BendixKing read the full ADS-B spec and implement it? Something that the portable electronics folks have managed to do for a few hundred dollars? Their folks at the show had no answer to this, though they acknowledged that they were losing customers every day to Garmin.

Avidyne is another good example of corporate suicide. They made roughly 4,000 PFD/MFD glass cockpits for Cirrus aircraft until the OEM switched to the Garmin G1000. Do they have an “in-the-box” solution for -G2 Cirrus owners that will put synthetic vision into the PFD and some ADS-B capabilities on the MFD? No. What are their customers doing? Converting to Garmin in a piecemeal fashion (soon it will be as tough to get maintenance for a Cirrus as for an old Cessna or Piper because the shop won’t have any idea what to expect for panel contents and wiring).

Speaking of suicide, how dangerous is it when 10,000 aircraft fly into a handful of airports in a small region for a week? KOSH supposedly saw 19,588 operations during an 11-day period (roughly 135 per hour during the 13 hours per day of official open time, so fairly close to a normal day at five-runway KATL (2,460 operations/day on average)). The NTSB database shows only four accidents in all of Wisconsin from July 1 through August 1, 2018. One of them was fatal, that of a 1950s DeHavilland Venom fighter jet. Some planes crashed before reaching Wisconsin, of course, but considering how many homebuilts and antiques gather it seems remarkably safe.

Airshow acts that I especially enjoyed:

  • David Martin in a Beechcraft Baron (amazing to see what can be done without exceeding the limits of a normal-category airplane)
  • Jim Peitz in an F33C Bonanza (amazing to see what can be done in a four-seat family airplane that was beefed up at the factory for aerobatics)
  • Jeff Boerboon in a “Yak-110” (two Yak-55s glued together… with a turbojet engine stuck in the middle)
  • Aaron Fitzgerald in the Red Bull Bo 105 helicopter (loops and rolls that you can do only once in a Robinson or Bell!)
  • Patty Wagstaff in an Extra 330S
  • Mike Goulian from our KBED home in an Extra 330SC
  • Philipp Steinbach in the GB1 GameBird (see previous post)
  • pair of Grumman F7F Tigercats (beautiful on the ground as well)

Least favorite airshow act: a synchronized drone array. These stayed pretty far from the crowd so it was essentially a bunch of lights that could have been replicated with a big TV (it is possible to project 3D onto 2D!). Unless the drones are all around a crowd I don’t understand why a 3D array of drones is more compelling to watch than a big TV (or your phone held up close to your eyes).

[Separately, would it still be fun to watch one of these aerobatics acts if entirely flown by computer? I couldn’t find anyone who thought it would be difficult to have software replicate the maneuvers, including adjusting for wind, of the aerobatic champions.]

The craziest people I met? A couple from Texas who spent 15 years building a turbine-powered Rotorway helicopter. He is a helicopter CFI so he plainly knows about the existence of used Robinson R22s! He now has 43 hours on the machine (half as many as one of our flight school’s R44s might fly in a busy summer month) and is already thinking about selling it to begin another project. Runner-ups: Essentially anyone who builds a kit airplane. The world is drowning in certified airframes. Why not take one, convert it to Experimental, and then do whatever is desired?

[Actually, the founder of EAA, Paul Poberezny, was a good example of this kind of craziness. He flew all kinds of high-performance aircraft in the USAF, including the P-51 Mustang. Then he came home to Wisconsin to build low-performance slab-sided airplanes and fly them. Imagine if a Ferrari race car driver decided to build dune buggies for fun.]

I’ve resolved to go to Oshkosh more frequently. In a world where almost everyone thinks it is crazy/stupid to fly light aircraft (why not buy a JetBlue ticket for $69 instead?), it is nice to be in an asylum for 100,000+ folks who love to fly despite the irrationality of it all.

Related:

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Robinson R66 makes it around the world

by philg

Two pilots in a Robinson R66 (plus ferry tank!) made it around the world in 97 days:

Their motto is “Empowering People” (not to be confused with Shaesta Waiz‘s “Empowering Women” and “Inspiring Women”!). But how many people will feel “empowered” if they learn that doing this requires years of training and suitcases full of cash?

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