A Canadian Multi-Crew Licence?

document.write(" serif">Canada's Flight Training Reputation

Trying to keep Canadian flight training competitive is a laudable goal. We have a well-deserved reputation for competence, earned the hard way by flying in our terrible weather around our huge unpopulated country with plenty of pressure to get there (sooner or later) because it's often the only way to get there.

Much training business has come to our shores because of this reputation. The way to keep it coming is to maintain and bolster our good reputation in these trying times.

Loss of Control Accidents

In the last decade the character of airline tragedies has changed completely. Modern aircraft are so reliable that engine and system failures are rare. Aircraft and crew are designed and trained to deal with these failures if they occur. What we are seeing instead are crew failures.

These have come to be called loss of control accidents. The well-known examples are AF447, Colgan Air at Buffalo, and now Asiana 214 at San Francisco. There are many more, including, most recently, Southwest at LaGuardia. These accidents were all caused by crew action (or inaction).

(That includes, by the way, AF447 and Colgan, in which icing played a peripheral role. Flying into known icing is something for which the crew is responsible.)

These accidents all have something in common: pilot incompetence.

I know that sounds harsh, but it must be said. It is an accurate statement. The pilots in these cases may have known their airplane fairly well. They may have memorized their company's operating manual and their Standard Operating Procedures. But in all cases they did not understand some of the basics of flying an airplane. Colgan and AF447 fell into the ground or sea with the wing stalled, not flying, because the pilots pulled back on the control column and held the back pressure despite warnings and stick shakers. The Asiana crew pulled back to stretch their glide, even though they were far gone on the back side of the drag curve, within a few knots of the stall.

What is missing in these cases is basic flying training. The causes are legion and still being debated, but the fix is simple. In order to get a license, especially a license to fly a large airplane with many paying passengers aboard, a pilot must demonstrate the ability to take off, fly, and land an airplane while keeping it within its safe envelope. He must, in other words, demonstrate competence.

Commercial Reasoning

Canada's proposed Multi-Crew Licence has this as its rationale: Canadian flight training operators providing commercial training to foreign candidates are unable to compete with foreign operators and risk losing a segment of their industry (my emphasis).

Under various names, the Multi-Crew Licence has had a role in most loss of control accidents.

On the face of it this license seems reasonable. There is always a Captain who has a real license to supervise the others with lesser licenses. But on closer inspection what we are really saying is that a pilot who cannot legally take a friend for a ride can occupy a cockpit seat while the captain is back in First Class (AF447, and the Korean Air flight shot down over the Kamchatka Peninsula). We speak of Crew Concept and Crew Resource Management, but if the only pilot who understands the basics is not on the flight deck, these concepts are moot.

Commercial pressures have brought us, step by innocent-seeming step, to where we are today. Each step seems reasonable, at least at the time. We now routinely fly two-engine airplanes on twelve hour overwater legs. Back in the 1970's that was unthinkable and illegal. In those days airplanes didn't land themselves. Now they can, under the right conditions, and some operations manuals even specify autolands as the normal procedure. Pilots who comply are soon incompetent, unable to land the airplane by hand. But in San Francisco last month the glidepath transmitters were shut down on both runway 28's. Indeed, they had been off since June 1. Manual landings were the only way at KSFO.

The Multi-Crew Licence seems like a logical next step in response to today's commercial pressures. In reality, it is the next step toward complete incompetence on all flight decks.

Public Assumptions

Airlines have done an excellent job marketing a service that whisks you to another continent at half the speed the sun moves. Even with today's oil prices, ticket prices are (in today's dollars) a fraction of what they were in the 1960's. This is the new normal. Flights are uneventful. Pilots are bus drivers. Airplanes land themselves, don't they?

An airplane crashes at San Francisco. There must have been something wrong with the engines. Or perhaps the autothrust? A nosegear collapses on landing at LaGuardia? Obviously a mechanical malfunction.

Marketing has succeeded in making aviation seem safe. But even though airplanes have changed since the 1930's, flying is still a dangerous adventure. The safe arrival of even today's incredible airplanes still depends on the good judgment of pilots.

We don't want to think about that, because pilots are people and can make mistakes. But we'll have to start thinking about it, and acknowledging it, or the crashes will continue.

Feeders, Discount Airlines, and the Elimination of Apprenticeship

Flying is an apprenticeship trade. Like any job worth doing, it takes dedication and a lifetime of learning. I have 45 years and 19,000 hours of experience and I am just beginning to understand how little I know. But I have survived so far and I am very serious about continuing to survive. Dying by your own hand at the controls of an airplane is an absolute no-no for a pilot.

I was lucky. I have had (and still have) many fine teachers. When I was a young airline pilot most captains still took their teaching responsibilities seriously. Today's young pilot is not assured of the same. Pressure on unions and pilot salaries is being applied by business methods: spawning and dividing feeders and discount airlines foremost among them. The goal is to lower costs, but the (perhaps unintentional) byproduct is the interruption of the contact between old and young pilots and the teaching and learning that allows. (I believe that lowering wages also directly reduces respect for the job and the job satisfaction of the worker, but that is an argument for another time.) The FAA's response to the Colgan Air crash was to raise the experience requirement for First Officers to 1500 hours, even though it was the captain who was flying and who stalled the airplane and even though the airline had given insufficient training to both pilots on icing and how their aircraft handles ice. I have always understood that pilots are paid to be responsible. I am bemused by today's response to accidents, where band-aids are liberally applied to wounds which obviously require surgery.

Conclusion

Introducing a Multi-Crew Licence in Canada would be just another band-aid papering over the serious issues facing aviation today. Don't do it!

Losing Competence Part V: Asiana 214 and the Loss of Control Accidents

document.write(" serif">Automation and Hubris

Bernard Ziegler designed the Airbus to be pilot-proof. He is a good pilot, and he noticed that many pilots are less skilled than himself. In the interest of safety, he designed an airplane that could not be stalled. But it has been known for thousands of years that hubris is followed by nemesis, that Pride goeth before destruction, and an haughty spirit before a fall. (Proverbs, 16:18)

Hubris is arrogance before the gods. The goddess Nemesis alone can see the fine line between doing the best work you can and believing that your work is somehow superior. Cross the line and she is ruthless, finding your fatal flaw and using it to bring you down.

AF 447 was the fall of the hero. Pilot carelessness led the airplane into a line of thunderstorms. Supercooled water drops overwhelmed the pitot heaters, temporarily removing all three sources of airspeed information. The autopilot dropped off. The flight control computers switched from Normal to Alternate Law. The airplane can be stalled in Alternate Law.

Human or robot, there is always a fatal flaw.

How can we work with imperfection?

Don't Bow Down

Mankind, when confronted with the complicated or the divine, tends to bow down in worship. This can be hazardous in aviation.

The new automation – glass cockpit, fly by wire, IRS and GPS – together bring a change at least as momentous as going from props to jets in the 1960's. The aircraft is now such a capable pilot on her own that she almost seems real. We called the Airbus Fifi. Rather than bowing down, we found it was much better to treat her like a person. Dare to know her and maintain a relationship.

In her early days, frustrated pilots would exclaim, “What the #$%* is it doing now?” On a go-around at KLGA the map display would disappear, the airplane sailing off the edge of the world because it had passed the last waypoint in the flight plan. Or on a miss from a visual approach at KMIA the power would suddenly go to idle. Finger trouble with the Autothrust. She was trying to maintain go-around speed.

But the answers are right in front of you on the FMA. (Flight Mode Annunciator, at the top of the Primary Flight Display) We began speaking for her, calling out any change in the FMA, so we all knew what she was doing, or thought she was doing.

And yes, most of the time she was a damn good pilot. Just as we are. Exactly the same, including the occasional lapse. Which is why there is more than one pilot aboard. And which is why the human pilot should never bow down and never step aside. Know her (the automation, Fifi, the airplane) as well as you can. Always monitor her as you would a human pilot and call out anything unusual. And if she's not doing what she is supposed to, take over. For those interested in pursuing the subject, there is an excellent video, Children of Magenta, of a lecture by an American Airlines training captain. The take-away is the same: if she's not doing what you want, take over and fly by hand. You don't have time to figure out what you did wrong with the automation.

Crew Concept – and Not Just Humans

Moving from props to jets, pilots were introduced to many new concepts: mach tuck, dutch roll, deep stall, etc. Perhaps the most important were the long, shallow drag curve and the slow spool-up time of the engines.

Moving into the fly-by-wire era, we have to accept that the airplane (her automation) is part of the crew. Philosophically, it is perhaps a stretch, but in the real world of the cockpit it is a game changer and a life saver. As soon as you accept that the airplane is part of the crew – not a superior or inferior, but an equal – everything starts to make sense. She sounds the cricket as the autopilot drops off. In Alternate Law she says Stall, Stall as the panicked pilot pulls back on the sidestick.

But if you're on approach below 1000 feet (critical phase of flight) and the descent rate is 1300 feet per minute and the airspeed is below Vapp then someone isn't doing what needs to be done. (Without a glideslope the airplane will not understand that something is wrong.) The software doesn't care if the airplane crashes. She is a good pilot but she has absolutely no self-preservation instinct, no will to live. Human pilots have, or they have no place on the flight deck.

Losing Competence Part IV: Asiana 214 and the Loss of Control Accidents

document.write(" serif">The Drag Curve

Why did I say, yesterday, that saying pull back was exactly the wrong thing to do?

 

This is a drag curve. Every airplane has one. This looks like the drag curve of a small airplane, say a C-172. The curve for the B-777 is the same, except stretched out in the speed axis, like this:

During descent a jet's engines are at idle. Descending at perhaps 320 knots, it is near the right-hand end of the curve. Because of the 250-knot speed limit below 10,000 feet, at about 12,000 feet the pilot will pull back on the control column and hold the nose a little higher, slowing the rate of descent and trading kinetic energy (speed) into potential energy (reducing the rate of descent). As he does so he is moving left on the speed axis, toward the low point of the drag curve. Notice that drag is reducing as he slows. This means the rate of descent will decrease.

As he slows further for approach, he moves toward the low point of the curve. As you can see, in a jet the curve at this point is pretty flat, so the transition from one side of the curve to the other is a subtle one, covering, let's say, from 170 knots to 220 knots. In this range the pilot can pull back, raise the nose, and slow down without much affecting the rate of descent. Subtle though it is, this low point on the curve, the minimum drag speed, is extremely important.

Why? Because as he slows further for final approach, say to 137 knots, he is on what pilots call the back side of the drag curve. (You will more often hear back side of the power curve, but it is the same thing.) Everything changes on the back side of the drag curve. Slower speed requires more power, not less. If you don't add power, pulling back increases the descent rate. Pilots know that to stretch a glide, you (counterintuitively) have to push, not pull.

In a jet Vapp (final approach speed) is quite a way up the left side of the curve. You can see that as you slow, the drag increases, causing you to slow further. The airplane is “speed unstable”, which means that a small change in speed from turbulence or control input becomes a larger change if left to itself. What the pilot has to do is “catch” the speed as he approaches Vapp by adding power. The pilots of Asiana 214 forgot this step, and continued to slide up the left side of the curve.

There is an old pilot saying: Pull back, you go up. Pull back more, you go down. Now you are closer to understanding why, but you may ask, What happens when you get to the end, where the curve stops? To answer, we have to look at the lift curve.

Instead of drag and speed, we are now graphing lift against Angle Of Attack (AOA, or alpha). (In 1G flight there is an equivalence between AOA and speed, so it's OK to think of the AOA axis as speed, except in this graph slow is on the right, with larger angles of attack.)

AOA is the angle at which the air meets the wing. What pulling back on the stick or the control column really does is increase the angle of attack. So if the pilot needs to increase lift, he pulls back, moving along the curve to the right. But the wing only “flies” in a narrow range of AOA, from 1 degree or less up to about 16 degrees. Above that the airflow starts to detach from the upper surface of the wing and the wing rapidly loses efficiency. That is called the stall. Now the wing is more like a board. It is still pushing air around, but not nearly as much air. The wing is stalled.

You can see in the graph that as you move to the right, increasing angle of attack, lift increases in a straight line and then suddenly goes over the top like a roller coaster track. Indeed, that's just what it feels like when an aircraft stalls. Now as you pull back more lift decreases, and the bottom drops out. That's what happened to Air France 447. When the autopilot kicked off the pilot panicked and pulled. For a brief period they went up. The pilot kept pulling, and for four minutes the aircraft fell, at angles of attack well above the stall, until it hit the sea.

So that's why the drag curve ends on the left-hand side. The end of the curve is the stall. Asiana 214 was almost there, and that's why the stick shaker went off. They weren't stalled yet, but they were within a whisker. They were sitting on top of the roller coaster. And when they pitched up even further in that last second before impact (you can see it clearly the YouTube Video and in this re-enactment) it did nothing to change their flight path. All it did was lower the tail and landing gear.

Now you know why.

Next: Why aren't pilots better trained and more experienced?

Losing Competence Part II: Asiana 214 and the Loss of Control Accidents

document.write(" serif">News and Public Relations

Deborah Hersman, The NTSB's Chairwoman, has taken some flak in the last few days. But from my perspective, she is one of the few in responsible positions who are looking good.

First a minor annoyance: on Saturday and Sunday news outlets kept repeating a young witness's observation that Asiana 214 came in “low and fast.” Many immediately available facts, including where the aircraft came to rest, made it a slam dunk that the aircraft was, instead, flying way too slowly.

Then on Monday the Korean Government announced they would be “inspecting all Korean B-777's”. On Tuesday and Wednesday various pilot unions called for Ms. Hersman's head, saying presumptions of pilot error were speculative and premature.

Please. I am used to the power players grandstanding their interests, but this is amateur hour. There is only so much ignorance out there.

The Last Thirty Seconds

Now let's get back to what we know. The cockpit cleared the breakwater nicely. The main landing gear and the tail did not. The speed at impact was 106 knots, within a knot or two of the stall speed. (The approach speed should have been 137 kt.) One and a half seconds before impact, engine power increased. Passengers in seats just behind the wing could see spumes of water being thrown up. At four seconds before impact the stick shaker operated, signifying an impending stall. At seven seconds someone is heard on the voice recorder calling for an increase in speed. In his interview the training captain said he went to push the throttles forward but the trainee already had. (Notice at least 5 1/2 seconds elapse between advancing the throttles and the increase in power. Seven seconds spool-up from idle is typical for a fanjet engine.) At 500 feet altitude the training captain became aware that they were too low (the PAPI lights were red over red) and he asks the trainee to pull back. The training captain also notices they are not aligned with the runway. Ms. Hersman says at that point they knew they were low and they were making lateral corrections to line up on the centerline of the runway.

These are the bare facts.

Flight Preparation in Seoul

Now let's go back twelve hours or so to the pilots' briefing. The dispatcher has already produced the flight plan with its route as close as possible to the minimum time track. The weather is good over the Pacific and at destination. Most likely they have fuel for a close alternate, such as Sacramento. It looks easy. But somewhere in the data available to the dispatcher and pilots are these two lines:

ISFO 06/005 SFO NAV ILS RWY 28L GP OTS WEF 1306011400-1308222359

ISFO 06/004 SFO NAV ILS RWY 28R GP OTS WEF 1306011400-1308222359

San Francisco airport (KSFO) always lands on runways 28L and 28R unless a winter storm blows through. With today's light winds and good visibility it is a near certainty that these runways will be in use. But decoding the two lines above (they are called NOTAMS, for Notices To AirMen) we find that the GlidePath (GP) is OuT of Service (OTS) for both runways. The When in EFfect (WEF) is from June 1, 2013 to August 22, 2013 at midnight. This is important because the aircraft cannot fly these approaches on autopilot in the way the pilots are used to.

Here is where we have to move into sensitive territory. (There will be more of these before we're done.) At the end of the article Terror on Jet, in The New York Times on Monday, July 8, we find these lines:

Some experts said that pilots often have little opportunity to practice landings without the aid of such technology . . .

Still, given that the weather was ideal and the guide lights (PAPI, or Precision Approach Path Indicator) were on, making a visual landing should not have been difficult for most commercial pilots . . .

on a difficulty scale of 1 to 10, this was a 2 or 3 at the most . . .

Pilot Judgment

A pilot's most important skill is his judgment. (see my Developing Pilot Judgment) He must look at the tasks and maneuvers ahead and ask two questions: Can the airplane do it? and Can I do it?

The former is mostly hard data in the Aircraft Flight Manual Limitations section, but it is also practical knowledge of what the aircraft's systems can and can't do and an understanding of the feedback systems that tell the pilot if the job is being done. (A good example is the AutoThrottle).

The latter question is the more important of the two: Can I do it? The only way to answer is through experience, and it is not measured in flight hours.

Training: have I been trained in this maneuver?

Practice: have I practiced it on my own? What were the results?

Recency: have I done one in the last 30 days? 90 days?

When Asiana's pilots were preparing for the flight in Seoul, the two NOTAM lines about the glidepaths on 28L and 28R should have triggered a dialogue:

We're going to have to do an everything-off visual approach in KSFO. Has any of us been trained for this? Who has practiced one in the last year? Which of us has done one in the last 30 days? 90 days?”

I'd be willing to bet (I'll back this up in future installments) that none of the four pilots had flown a visual approach in the last 90 days. In that case, pilots with sound judgment would never have attempted the visual approach to 28L in KSFO. They would have diverted to Sacramento where there were long runways with functioning ILS systems.

Next: what else they did wrong . . .

Losing Competence: Asiana 214 and the “Loss Of Control” Accidents

document.write(" serif">Introduction

Asiana 214 is in my dreams. All day her last two minutes of manually controlled flight replay in my head. Searching for a cause does not distress me. The pilots were clearly incompetent. But how did we get to this pretty pass? My overwhelming sense that that's where we are distresses me greatly.

For the last few years disasters like this one have come to be known as “Loss Of Control” accidents. It's a catchy label, but it doesn't get to the heart of the matter. The pilots of these airplanes – I'm thinking of Colgan Air at Buffalo, Air France 447, and Asiana 214, but there are many more – these pilots fundamentally did not understand what was happening, so they were unable to do their jobs.

How has this come about? And how can it be fixed?

At this point I don't know if this is going to be a blog, a series of blogs, or a book. I know only that I must explain the technical issues, explore the commercial and financial forces as they interact with my trade, and try to map a path through this crisis.

Flying has grown into a huge industry. The era of limitless supplies of hugely keen, military-trained pilots is over. Worldwide, there will be a demand for over 600,000 pilots in the next decade. Where will they come from?

I love flying. Most of my working life has been in airplanes, flying and teaching. I see flying as a living link between the sailors of the past from Magellan to Jack Aubry and the space explorers of the future like Jim Kirk and Jean-Luc Picard.

Sailing, navigating, flying: these have always been apprenticeship trades. You learn the theory, but you also learn the practical, the hands on. You practice. You repeat. You get sharper. Gradually you come to understand what you have to do to stay sharp, to stay competent. (Or, in airline-speak, to maintain your compentency.) Then you pass your knowledge on.

Somehow this process has broken down. There is no single villain, no smoking gun. Instead there are many villains conspiring unwittingly, starting with you and me, airline customers, frequent flyers, looking for a painless flight and, most of all, for a deal.

Training a pilot, says Transport Canada (in the Flight Instructor's Guide), must be done right the first time. The pilot can't see his airplane moving through the air, because most of the time air is invisible. Instead he must imagine the air flowing over his wings and through his engines, and imagine the air pushing on his slipping or skidding fuselage and fin. Above all he must imagine the angle the airflow makes meeting his wings and how this critical parameter is related to lift and airspeed. He must viscerally feel the drag curve as he controls this angle, the Angle of Attack, as he slows his airplane for approach and landing. He must understand at all times where he is on that curve and what the consequences are. He must know how to fly.

It is not as easy as 1, 2, 3. It requires work and practice, and most of all it requires imagination.

Pilots don't call it that, of course. That sounds too much like an artist, an inventor, or a writer. Pilots refer to it as Situational Awareness. It's what was missing in all of these “Loss of Control” accidents. But why? And how can we fix it?

More to come . . .

The French in Denial

It could happen to anyone. This time it happened to be a French airplane with French pilots flying for a French airline.

For two years the “black boxes” (the voice recorder and the DFDR) lay in peace on the floor of the Atlantic Ocean, 13, 000 feet below the waves. For two years there was conjecture, speculation, and (some quite fine) attempts at reconstruction. Then the black boxes surfaced, along with other hard evidence, including the jackscrew from the Trimmable Horizontal Stabilizer.

For months as the Bureau d'Enquêtes et d'Analyses slowly released information, we (and the BEA) put together the tragic and terrifying story. But the story stopped abruptly, the last chapter removed or never written.

Now a French aviation writer, Jean-Pierre Otelli, has published that last chapter independently of Air France, Airbus Industrie, and The BEA. The story ends as we knew it would – badly and sadly – but now we have more grisly detail and less room for denial.

The Bureau d'Enquêtes et d'Analyses is incensed. In a press release on October 13, 2011, (look under News in the sidebar) they claim that the transcription released by Otelli “mentions personal conversations between the crew members that have no bearing on the event, which shows a lack of respect for the memory of the late crew members” (my emphasis). The same day the London Telegraph published an account of the final minutes. The account seems to have been shortened since October 13, and I have been unable to find the original. Those who are interested may add the following after “According to an official report released earlier this year, the last words were from Captain Dubois who said: 'Ten degrees pitch.'”:

But in his new book Mr Otelli asks who will be held responsible 'for this mess'. 'Is it a training problem, fatigue, lack of sleep, or is it due to the fact the pilots are confident that an Airbus can make up for all errors?,' he writes. France's air accident investigation unit, the BEA, reacted angrily to the publication of the book, with a spokesman saying printing the conversation showed a 'lack of respect to the memory of the crew who died'. Air France has denied that its pilots were incompetent, but has since improved training, concentrating on how to fly a plane manually when there is a stall. Both Air France and Airbus are facing manslaughter charges, with a judicial investigation led by Paris judges already under way. A judge has already ordered Air France to pay some £120,000 in compensation to the families of each victim, but this is just a provisional figure which is likely to multiply many times over. THE FINAL MOMENTS Marc Dubois (captain): 'Get your wings horizontal.' David Robert (pilot): 'Level your wings. 'Pierre-Cedric Bonin (pilot): 'That's what I'm trying to do... What the... how is it we are going down like this?'Robert: 'See what you can do with the commands up there, the primaries and so on…Climb climb, climb, climb. 'Bonin: 'But I have been pulling back on the stick all the way for a while. 'Dubois: 'No,no, no, don't climb. 'Robert: 'Ok give me control, give me control.'Dubois: 'Watch out you are pulling up. 'Robert: 'Am I?'Bonin: 'Well you should, we are at 4,000.'As they approach the water, the on-board computer is heard to announce: 'Sink rate. Pull up, pull up, pull up. 'To which Captain Dubois reacts with the words: 'Go on: pull.'Bonin: 'We're pulling, pulling, pulling, pulling.'The crew never discuss the possibility that they are about to crash, instead concentrating on trying to right the plane throughout the final four minutes. Dubois: 'Ten degrees pitch. 'Robert: 'Go back up!…Go back up!…Go back up!… Go back up! 'Bonin: 'But I’ve been going down at maximum level for a while.'Dubois: 'No, No, No!… Don’t go up !… No, No! 'Bonin: 'Go down, then!'Robert: 'Damn it! We’re going to crash. It can’t be true!'Bonin: 'But what’s happening?!'The recording stops.

What we know, briefly, is this: Air France 447 ventured into a line of thunderstorms along the InterTropical Convergence Zone. Four other flights diverted around the storms. In the zone the flight encountered unusually warm temperatures and supercooled water droplets – enough to briefly overwhelm the heaters in all three pitot tubes, denying airspeed information to the Flight Control Computers for long enough to cause them to kick off the autopilot and to degrade the flight controls from Normal Law to Roll Direct/Pitch Alternate Law. Despite the fact that by the book they were too heavy to climb, the pilot flying (First Officer David Robert) zoomed up from 35,000 feet to almost 38,000 feet, dissipating the aircraft's energy and exposing it to coffin corner, where Mach buffet meets stalling speed. With brief lapses he held back pressure on the sidestick for the remainder of the flight.

First the airplane stalled (quit flying because the Angle of Attack was too great). Then, because of the steady back pressure on the sidestick, the autotrim wound the Trimmable Horizontal Stabilizer (more powerful than the elevators) to full nose up. (The THS jackscrew was found in this full nose up condition). By now the aircraft was in a deep stall, falling almost straight down in a near-level attitude.

There is plenty of room for argument about why it happened this way. Many (including David Learmount at Flight Global and myself) have started that discussion. It must continue, because we must know not only why F/O Robert stalled the aircraft, but much more importantly why he didn't know he had stalled it, why he had a totally inaccurate picture of what was happening, and why there was a complete absence of situational awareness on that Flight Deck.

It may look as if I am placing blame solely on F/O Robert. Absolutely not. That would be much too easy. I and others have already written many pages (see AF447 on my blog) trying to piece together all the factors at work in this accident. We will write many more.

As in all accidents, there is a chain of events and decisions which gradually (at first!) reduce maneuvering room. The first of these was Captain Dubois' decision to take crew rest approaching the ITCZ.

But before that came Air France's decision to carry less fuel than the spirit of the regulations requires, by filing the Flight Plan as Rio to Bordeaux, alternate Paris. Even earlier, the brilliant (I am not being ironic or facetious, I admire the man) Bernard Ziegler designed the Airbus to be “pilot-proof” and impossible to stall. However he (or his designers) also left the autotrim functional in Pitch Alternate Law, an oversight I believe should be corrected ASAP. Finally, (and earliest of all) you and I and everyone else who has traveled since Airline Deregulation in 1978 believes or wants to believe in cheap seats.

It could happen to anyone.

Sadly, it has all been foreseen. Recently I read an article which bluntly calls out the forces that led to this accident. It is called The Training Paradox, and was written by pilot, engineer, and lawyer Mark. H. Goodrich. Some of the accidents and incidents he describes stood my hair on end. Unfortunately I cannot provide a link to it. I read it in Position Report, November 2011, Volume VIII Number 3. (This is the magazine of the Retired Airline Pilots of Canada).

The very experienced and knowledgeable Mr. Goodrich shows how the forces of deregulation have derailed traditional career paths and interrupted the passing along of knowledge. As a result, the craft, the trade, the profession if you will of flying is dying a slow death. Neither are regulatory bodies or airline management immune from this decay.

This time it was the French. It is not surprising they are in denial. But it could happen to anyone, and it will.

 

AF 447: Let's Talk About Why – 1

Thanks to the work of David Learmount at Flight Global, and that of the Wood's Hole Oceanographic Institution and the Bureau d’Enquêtes et d’Analyses, enough is now known about this accident to start looking for useful lessons and to analyze the data along with the BEA. Flight safety and the future of the piloting profession depend on this becoming a wide and serious conversation.

Pilots obsess about accidents for good reason. There is always so much to learn. The AF447 tragedy is an epochal example.

There is a mind-boggling number of lessons to be learned here, in a host of areas and disciplines: Pilot Training, Standard Operating Procedures, Instrument Flight, and Aircraft Design are but a few of them.

I will commit today to joining the conversation. I begin with a consideration of Angle of Attack.

Angle of Attack

Wolfgang Langewiesche (father of William) emphasized Angle of Attack in his excellent Stick and Rudder, published in 1944. Advocacy of AoA was an uphill battle then and it still is today. Instead of talking about AoA, we prefer to use airspeed and explain why certain speeds we use change with aircraft weight and G loading. Many or even most aircraft flying today have no Angle of Attack indication. The accident aircraft had two AoA sensors. The flight recorders had access to the signals from these sensors but the pilots did not, at least not when they needed it most.

Lift is produced when the air flowing over the top of a wing has a longer distance to travel than the air flowing underneath. The air “stretching out” over the top produces a lower pressure, allowing the higher pressure underneath to push the wing up. There is a caveat, however. The airflow must remain attached to the upper surface of the wing.

Imagine a cross-section of wing, with a line drawn from the middle of the rounded leading edge to the pointed trailing edge. This is the chord line. Now imagine an arrow pointing at the leading edge. This is the airflow.

If the arrow meets a (symmetrical) wing head-on there will be no lift. But let the wing meet the air at a slight angle and the airflow around the wing will no longer be symmetrical: it will meet the rounded leading edge at an angle and it will divide lower on the curve of the leading edge. The air flowing over the wing will have a longer distance to travel. Lift will be produced.

The angle at which the airflow meets the chord line is called the Angle of Attack. Up to a point, increasing the Angle of Attack will increase lift. But beyond a certain point – usually about 16° – lift will instead decrease because the airflow is beginning to separate from the upper surface of the wing. This is called the aerodynamic stall, and it always happens at the same Angle of Attack.

Angle of Attack is controlled by the elevators, the control surfaces on the trailing edge of the horizontal tail. When the pilot pulls back on the stick, the elevators lift, causing a down-force on the tail and forcing the wing to meet the air at a higher Angle of Attack. Trim tabs (small surfaces at the trailing edge of the elevators) can be moved to change the neutral position of the stick. (Another way to think of it is the trim tabs change the Angle of Attack at which there is zero stick force.)

In a modern jet transport the entire horizontal tail is usually moveable. This is because of the very wide speed range of the jet and because flaps and leading edge slats also change the “trim.” The other side of the coin is that this horizontal tail, or stabilizer, is very powerful in modern jet transports. A runaway stabilizer is a true emergency. Traditionally there has been a STAB IN MOTION aural warning, and an emergency cutout switch close to hand. Most cases where the stabilizer ran all the way up or down in flight have resulted in the loss of all on board.

In most aircraft the pilot is used to trimming as he flies. A change of speed or configuration, be it in a Beech Bonanza or a DC-9, will require a trim change. With some experience on type the pilot knows (for example on a DC-9) that extending the leading edge slats will require two beeps (of the STAB IN MOTION aural warning) of nose-up trim. He can use the thumb switches on the yoke to move the stabilizer as the slats are extending and thus remain stick-neutral during the configuration change. This is part of anticipation, or staying ahead of the aircraft.

Airbus aircraft, from the A320 onwards, are different. They are fly by wire, where computers are interposed between the pilots' sidestick inputs and the control surfaces. This arrangement allows some elegant additions to aircraft design, such as envelope protection (which among other things makes it impossible for the pilot to stall the aircraft) and, relevant to our discussion today, stick force per G and autotrim.

In Normal Law, which is where the Airbus is most (and the pilot hopes, all) of the time, configuration changes can be made hands off, even flying by hand. Of course the pilot has the tips of his fingers on the sidestick, but he can make a configuration change with no pitch input because the control system, in Normal Law, will maintain 1G flight. When he calls for FLAP 1 and the leading edge slats extend, the nose-down pitch is sensed and countered by the system, maintaining 1G flight. (1G is what you experience sitting in a chair at home or in an aircraft at cruise in smooth air). In effect, the airplane is doing the anticipation for the pilot.

Like the transition in the late 1950's from props to jets, fly-by-wire has been a major change for pilots. In general we welcome it for the many advantages it offers.

Experience has shown that to do his job, which is to ensure the safe arrival of his aircraft, the pilot must fully understand a much more complex airplane. Chesley Sullenberger reached up and started the APU (the Auxiliary Power Unit, a small turbine in the tail which can supply electrical and hydraulic power on the ground or in flight) as soon as his engines lost power. Why? Because he knew his airplane and he knew he wanted to keep it in Normal Law until touchdown.

The transition from props to jets was all about speed range, speed brakes and spoilers, high Mach number, coffin corner, Dutch Roll and super-stall, but in everyday life it was more about high drag on approach, no propwash, slow spool-up times, and operating on the back side of the power curve. This change took some adjustment on the part of pilots: the more experienced pilots had more adjustments to make. The same is true with the transition to fly-by-wire.

In a traditional airplane the pilot controls Angle of Attack with the elevator and the trim tabs or stabilizer. (More often he will be thinking of Airspeed, which is the constant-weight, 1G manifestation of AofA). He is used to feel, which is essentially the change in elevator neutral point with AofA. Should the aircraft slow on approach, the nose will get “heavy”, prompting him to pull back or trim nose-up.

That feel is totally absent in Airbus aircraft. (Boeing, in the B777, have added artificial feel to their fly-by-wire system). The Airbus pilot points and shoots, so to speak. Flying by hand he can take the bird, turning on a symbol (like a bird or an aircraft seen from behind) on his Primary Flight Display. The bird shows where his velocity vector is pointed; in other words, where is airplane will be so many seconds from now if he makes no further adjustments. On approach he can pin the bird on his flare point on the runway and either let the autothrust take care of the speed or adjust the thrust levers manually. If he does the latter, he must remember that there is no feel or feedback in the sidestick.

Obviously there are quite different assumptions operating during an approach in a Bonanza, one one hand, and an Airbus, on the other. This is not necessarily a bad thing. Take for example driving a car versus riding a motorcycle. In a car you steer with the steering wheel. In a motorcycle you counter-steer, putting pressure on the inside foot-peg and forward pressure on the inside bar, in effect trying to steer the front wheel the opposite way.

But you know you're on a motorcycle and not in a car. You have learned how to ride a motorcycle.

Consider, however, flying an Airbus if something goes wrong with a sensor or a computer and you wind up in Alternate Law or Direct Law. You are in the same vehicle but suddenly the rules have changed; the assumptions have changed. It is, in effect, no longer the same machine. This is a recipe which messes with a pilot's head.

Unfortunately, experience has shown that Direct Law, where control displacement is proportional to stick force and the airplane handles like a wet fish, is actually the more benign of the two degraded modes. There is a big message in red on the ECAM saying USE MAN PITCH TRIM. The pilot moves the THS (Trimmable Horizontal Stabilizer) by moving a wheel almost a foot in diameter. This is old-style, normal airplane flying, commanding AofA with stick force and trim. There is still no feel in the sidestick, but the procedure is familiar.

Alas, in Alternate Law there is no such familiarity. It is still point-and-shoot, sort of, but autotrim is still working. As long as there is back pressure on the stick the THS trims nose-up, and vice-versa. There is NO Stabilizer in Motion warning except the movement of the trim wheels. That would seem to be an easy thing to detect, but I can testify from personal experience that it is not. On every landing (in Normal Law) the flight control computers memorize the attitude at 50 feet Radio Altitude and at 30 feet start rolling in nose-down trim, in effect trying to mimic the feel of a normal aircraft slowing in the flare. In almost a decade of flying as Captain and Training Captain, whether as Pilot Flying or Pilot Not Flying, I cannot remember ever seeing the trim wheels move.

In two recent accidents an Airbus has hit the ocean with the THS wound to full nose up. In both cases the aircraft was in Alternate Law.

I am not an engineer. There are likely many ramifications that have not crossed my mind. But sitting here this afternoon my personal recommendation would be as follows:

Disable Autotrim in Alternate Law

AF 447: Let’s Talk About Why – 1

Thanks to the work of David Learmount at Flight Global, and that of the Wood's Hole Oceanographic Institution and the Bureau d’Enquêtes et d’Analyses, enough is now known about this accident to start looking for useful lessons and to analyze the data along with the BEA. Flight safety and the future of the piloting profession depend on this becoming a wide and serious conversation.

Pilots obsess about accidents for good reason. There is always so much to learn. The AF447 tragedy is an epochal example.

There is a mind-boggling number of lessons to be learned here, in a host of areas and disciplines: Pilot Training, Standard Operating Procedures, Instrument Flight, and Aircraft Design are but a few of them.

I will commit today to joining the conversation. I begin with a consideration of Angle of Attack.

Angle of Attack

Wolfgang Langewiesche (father of William) emphasized Angle of Attack in his excellent Stick and Rudder, published in 1944. Advocacy of AoA was an uphill battle then and it still is today. Instead of talking about AoA, we prefer to use airspeed and explain why certain speeds we use change with aircraft weight and G loading. Many or even most aircraft flying today have no Angle of Attack indication. The accident aircraft had two AoA sensors. The flight recorders had access to the signals from these sensors but the pilots did not, at least not when they needed it most.

Lift is produced when the air flowing over the top of a wing has a longer distance to travel than the air flowing underneath. The air “stretching out” over the top produces a lower pressure, allowing the higher pressure underneath to push the wing up. There is a caveat, however. The airflow must remain attached to the upper surface of the wing.

Imagine a cross-section of wing, with a line drawn from the middle of the rounded leading edge to the pointed trailing edge. This is the chord line. Now imagine an arrow pointing at the leading edge. This is the airflow.

If the arrow meets a (symmetrical) wing head-on there will be no lift. But let the wing meet the air at a slight angle and the airflow around the wing will no longer be symmetrical: it will meet the rounded leading edge at an angle and it will divide lower on the curve of the leading edge. The air flowing over the wing will have a longer distance to travel. Lift will be produced.

The angle at which the airflow meets the chord line is called the Angle of Attack. Up to a point, increasing the Angle of Attack will increase lift. But beyond a certain point – usually about 16° – lift will instead decrease because the airflow is beginning to separate from the upper surface of the wing. This is called the aerodynamic stall, and it always happens at the same Angle of Attack.

Angle of Attack is controlled by the elevators, the control surfaces on the trailing edge of the horizontal tail. When the pilot pulls back on the stick, the elevators lift, causing a down-force on the tail and forcing the wing to meet the air at a higher Angle of Attack. Trim tabs (small surfaces at the trailing edge of the elevators) can be moved to change the neutral position of the stick. (Another way to think of it is the trim tabs change the Angle of Attack at which there is zero stick force.)

In a modern jet transport the entire horizontal tail is usually moveable. This is because of the very wide speed range of the jet and because flaps and leading edge slats also change the “trim.” The other side of the coin is that this horizontal tail, or stabilizer, is very powerful in modern jet transports. A runaway stabilizer is a true emergency. Traditionally there has been a STAB IN MOTION aural warning, and an emergency cutout switch close to hand. Most cases where the stabilizer ran all the way up or down in flight have resulted in the loss of all on board.

In most aircraft the pilot is used to trimming as he flies. A change of speed or configuration, be it in a Beech Bonanza or a DC-9, will require a trim change. With some experience on type the pilot knows (for example on a DC-9) that extending the leading edge slats will require two beeps (of the STAB IN MOTION aural warning) of nose-up trim. He can use the thumb switches on the yoke to move the stabilizer as the slats are extending and thus remain stick-neutral during the configuration change. This is part of anticipation, or staying ahead of the aircraft.

Airbus aircraft, from the A320 onwards, are different. They are fly by wire, where computers are interposed between the pilots' sidestick inputs and the control surfaces. This arrangement allows some elegant additions to aircraft design, such as envelope protection (which among other things makes it impossible for the pilot to stall the aircraft) and, relevant to our discussion today, stick force per G and autotrim.

In Normal Law, which is where the Airbus is most (and the pilot hopes, all) of the time, configuration changes can be made hands off, even flying by hand. Of course the pilot has the tips of his fingers on the sidestick, but he can make a configuration change with no pitch input because the control system, in Normal Law, will maintain 1G flight. When he calls for FLAP 1 and the leading edge slats extend, the nose-down pitch is sensed and countered by the system, maintaining 1G flight. (1G is what you experience sitting in a chair at home or in an aircraft at cruise in smooth air). In effect, the airplane is doing the anticipation for the pilot.

Like the transition in the late 1950's from props to jets, fly-by-wire has been a major change for pilots. In general we welcome it for the many advantages it offers.

Experience has shown that to do his job, which is to ensure the safe arrival of his aircraft, the pilot must fully understand a much more complex airplane. Chesley Sullenberger reached up and started the APU (the Auxiliary Power Unit, a small turbine in the tail which can supply electrical and hydraulic power on the ground or in flight) as soon as his engines lost power. Why? Because he knew his airplane and he knew he wanted to keep it in Normal Law until touchdown.

The transition from props to jets was all about speed range, speed brakes and spoilers, high Mach number, coffin corner, Dutch Roll and super-stall, but in everyday life it was more about high drag on approach, no propwash, slow spool-up times, and operating on the back side of the power curve. This change took some adjustment on the part of pilots: the more experienced pilots had more adjustments to make. The same is true with the transition to fly-by-wire.

In a traditional airplane the pilot controls Angle of Attack with the elevator and the trim tabs or stabilizer. (More often he will be thinking of Airspeed, which is the constant-weight, 1G manifestation of AofA). He is used to feel, which is essentially the change in elevator neutral point with AofA. Should the aircraft slow on approach, the nose will get “heavy”, prompting him to pull back or trim nose-up.

That feel is totally absent in Airbus aircraft. (Boeing, in the B777, have added artificial feel to their fly-by-wire system). The Airbus pilot points and shoots, so to speak. Flying by hand he can take the bird, turning on a symbol (like a bird or an aircraft seen from behind) on his Primary Flight Display. The bird shows where his velocity vector is pointed; in other words, where is airplane will be so many seconds from now if he makes no further adjustments. On approach he can pin the bird on his flare point on the runway and either let the autothrust take care of the speed or adjust the thrust levers manually. If he does the latter, he must remember that there is no feel or feedback in the sidestick.

Obviously there are quite different assumptions operating during an approach in a Bonanza, one one hand, and an Airbus, on the other. This is not necessarily a bad thing. Take for example driving a car versus riding a motorcycle. In a car you steer with the steering wheel. In a motorcycle you counter-steer, putting pressure on the inside foot-peg and forward pressure on the inside bar, in effect trying to steer the front wheel the opposite way.

But you know you're on a motorcycle and not in a car. You have learned how to ride a motorcycle.

Consider, however, flying an Airbus if something goes wrong with a sensor or a computer and you wind up in Alternate Law or Direct Law. You are in the same vehicle but suddenly the rules have changed; the assumptions have changed. It is, in effect, no longer the same machine. This is a recipe which messes with a pilot's head.

Unfortunately, experience has shown that Direct Law, where control displacement is proportional to stick force and the airplane handles like a wet fish, is actually the more benign of the two degraded modes. There is a big message in red on the ECAM saying USE MAN PITCH TRIM. The pilot moves the THS (Trimmable Horizontal Stabilizer) by moving a wheel almost a foot in diameter. This is old-style, normal airplane flying, commanding AofA with stick force and trim. There is still no feel in the sidestick, but the procedure is familiar.

Alas, in Alternate Law there is no such familiarity. It is still point-and-shoot, sort of, but autotrim is still working. As long as there is back pressure on the stick the THS trims nose-up, and vice-versa. There is NO Stabilizer in Motion warning except the movement of the trim wheels. That would seem to be an easy thing to detect, but I can testify from personal experience that it is not. On every landing (in Normal Law) the flight control computers memorize the attitude at 50 feet Radio Altitude and at 30 feet start rolling in nose-down trim, in effect trying to mimic the feel of a normal aircraft slowing in the flare. In almost a decade of flying as Captain and Training Captain, whether as Pilot Flying or Pilot Not Flying, I cannot remember ever seeing the trim wheels move.

In two recent accidents an Airbus has hit the ocean with the THS wound to full nose up. In both cases the aircraft was in Alternate Law.

I am not an engineer. There are likely many ramifications that have not crossed my mind. But sitting here this afternoon my personal recommendation would be as follows:

Disable Autotrim in Alternate Law