ATC is 100

The world’s first civil aerodrome control tower was opened 100 years ago this month at London’s Croydon airport

Early in 1920 the UK Air Ministry decided that, with an average of 12 air movements a day, the air traffic at London’s main airport – Croydon – needed organising.

The ministry had no template for such a task, but issued a specification for a building they believed would do the job. It was to be called an aerodrome control tower, and the working part of it was to be “15ft above ground level, with large windows to be placed on all four walls”.

Radio communication was already in use, but even primitive radar would not be developed for another 20 years.

CATOs in radio communication with aircraft. Picture taken 1927

Radio direction-finding, however, provided the Civil Aviation Traffic Officers (CATOs) with the bearing from the airport of any aircraft transmitting a radio message, thus they could provide the crew with a course to fly to arrive overhead the aerodrome. They could also provide the pilots with weather information, including visibility, wind speed and direction, but also the approximate position of other traffic in the area so the crew could keep their eyes out for it.

Airline travel in 1920. An Airco de Havilland DH-4 plied the London Croydon – Paris Le Bourget route

Navigation was primitive in aviation’s early years. Clearly identifying the destination aerodrome so the crew landed at the right one was important. The pilots were helped to find the aerodrome by a bright, strobing “lighthouse” beam – green alternating with white – which was located on a high point. When control towers came in, the light was above the tower.

Croydon airport from above, 1925

Positive airfield identification was provided by very large lettering spelling out the airport name, either on the ground, or on the roof of a large hangar.

Separation between aircraft, if there was more than one near the aerodrome at any time, was assured visually by pilots looking out for other aeroplanes, with advice from the tower if necessary as to the position of potentially conflicting traffic.

Protocols about which of any two aircraft has the right to hold course and which should give way are set in the rules of the air, similar to the rules which mariners follow on the sea, and a disciplined circuit pattern over an aerodrome was a system with which pilots were familiar.

Permission to land or take off could be signalled by radio, or by a CATO shining a green aldis lamp toward the aircraft cockpit. Similarly, a red lamp would refuse permission. Firing off a green or red Verey flare from the tower was an alternative.

The UK’s principal air traffic management provider NATS is somewhat more sophisticated today! But its daily traffic tally is nearly 9,000 movements across the country, so it rather has to be.

P.S. Thanks to NATS for providing the colourised old photographs and historical detail from their archives.

 

 

 

Surely Shoreham can rise again

Gloster Gladiator at Shoreham Air Show in 2014

This summer it will be five years since the tragedy of that Hawker Hunter crash at the Shoreham Air Show. I think it’s time to start thinking about resurrecting the show once more.

This blog has seen extensive debate about what happened and why.

In fact the Shoreham crash and its investigation has been the most-discussed aviation subject by far since I started Learmount.com in early 2015. You can scroll back and find it all, if you’d like to, so I won’t go over it again.

Over the last four and a half years, on these pages I have set out the details of the Air Accident Investigation Branch inquiry, which was very thorough, and was highly critical of air show management at Shoreham in particular, but also in the UK as a whole. Things have changed since then.

Things did need to change. Even those icons representing the pinnacle of British aviation excellence – the Red Arrows and the Farnborough Air Show – changed the way they do things following the Shoreham inquiry.

Shoreham’s aerodrome is historic, one of the oldest in Britain, and perhaps the most beautiful. The airfield, and its air show, are part of this nation’s heritage.

The people of Shoreham and the Council have seen to it that those who died in the 2015 tragedy have a fitting memorial near the airfield on the River Adur

It’s right, and safe, to have another go.

Mitchell WW2 bomber taxiing, Shoreham Air Show 2014

Atlas Air crash should spark an overdue debate about piloting

Recent releases from the US National Transportation Safety Board’s investigation of the Atlas Air Boeing 767-300F fatal crash in February 2019 contain a vital message to the industry about loss of control in flight (LOC-I).

Unfortunately, the message could be overlooked, or not taken seriously, as it has been many times before.

The Atlas Air crash, however, finally negates a common reason for unconsciously dismissing the seriousness of a LOC-I accident.  This unconscious dismissal, among “Western” observers at least, is caused by the mindset that says: ‘It happened to a non-Western carrier’; the implication being ‘What would you expect?’.

Such pilot reactions to the Lion Air and Ethiopian 737 Max accidents flooded the web, particularly in the USA, and are still out there. The latter two accidents, however, involved an aggravated version of LOC-I, precipitated by a confusing technical distraction.

Right now, in the Atlas Air investigation, the NTSB is testing evidence that suggests pilot disorientation by somatogravic illusion might be pivotal in what happened. During descent toward its destination airport the aircraft finally dived steeply and at high speed into the surface .

A synopsis of the basic accident details can be found on the Aviation Safety Network.

A common example of somatogravic illusion – which is an acceleration-induced illusion – is the feeling that airline passengers get when their aircraft begins to accelerate along the runway; they perceive the cabin to be tilted upward, but a glance out the side window shows the aircraft is level, the nosewheel still on the ground.

Visual input, if available, is the dominant human sensory input, and it will correct the illusions caused by the reaction of the body’s balance organs to a linear acceleration.

The Atlas Air 767 freighter was inbound to Houston Intercontinental airport from Miami, and the flight phase in which things began to go wrong was a routine descent, the crew receiving vectors to avoid weather. As the aircraft was descending, in cloud, through about 10,000ft, cleared to 3,000ft, the crew were flying a vector heading of 270deg, and were told to expect a turn north on a base leg to final approach for runway 26L. All pretty normal.

There was a pilot call for “flaps 1”, the aircraft leveled briefly at 6,200ft, climbed very slightly, and its airspeed stabilised at 230kt. But shortly after that the engine power increased to maximum, and the aircraft pitched about 4deg nose up.

It is at this point that somatogravic illusion appears to have kicked in powerfully with the pilots. They had no external visual horizon because the aircraft was in cloud.

According to the NTSB, almost immediately the aircraft began a dramatic pitch down to -49deg, driven by elevator deflection. The airspeed ultimately increased to 430kt, and although the pitch-down angle was eventually reduced to -20deg, impact was inevitable.

The factor the NTSB is examining now is what triggered the sudden – apparently unwarranted – massive power increase. The cockpit voice recorder has captured a sound that may indicate the activation of the go-around button on the power levers. But neither of the pilots mentioned a need for go-around power.

About ten seconds after the power increase, caution alarms began to sound. The inquiry says the control column remained forward for ten seconds. According to FlightGlobal.com: “The aircraft transitioned from a shallow climb to a steep descent. Five seconds after the alarm commenced, one of the pilots exclaimed, ‘Whoa’, and shortly afterwards, in an elevated voice: ‘Where’s my speed, my speed’. Three seconds later, a voice loudly declares: ‘We’re stalling.’”

The flight data recorder gives the lie to the pilot’s stalling perception, because the angle of attack at that moment was safely below the stalling level.

During these remarks the thrust levers were brought to idle for about 2s, then were advanced again to their high power setting. During the transition from nose slightly up to nose steeply down, there were negative g-forces for nearly 11s.

Puzzling unknowns still lurk: like why a pilot exclaimed “where’s my speed?” when the indicated airspeed was rapidly increasing. Was it a fault of instrumentation, or of pilot instrument scan or perception at a moment of confusion?

The simple fact is that, every time a big engine-power increase takes place in flight, forward acceleration combined with a pitch-up moment caused by the underslung engines, is inevitable.

Just as inevitable – if this happens at night or in cloud – is somatogravic illusion in the pilots. “For this reason,” says the NTSB, “it is important that pilots develop an effective instrument scan.”

Develop? It’s a bit too late to develop a scan!

Recognising that acceleration brings with it the risk of disorientation, pilot conditioning should be to ignore all other sensory inputs except the visual, and with no external horizon that means concentrating totally on flight instruments, believing them, and controlling aircraft attitude and power accordingly.

Recurrent training must keep pilots alive to this risk, and to its remedy, but it clearly does not do this at present. Not for Asian, African nor for American pilots.

LOC-I has, since the late 1990s, been the biggest killer accident category for airlines. LOC-I linked to somatogravic illusion has frequently occurred, two of the most dramatic recent examples being the March 2016 FlyDubai Boeing 737-800 crash at Rostov-on-Don, and the August 2000 Gulf Air Airbus A320 crash at Bahrain International airport. Both occurred at night; both involved a go-around.

The FlyDubai pilot reaction to somatogravic illusion was a dramatic push-forward into a steep dive, like Atlas Air, and the aircraft smashed steeply into the runway.

The Gulf Air manoeuvre was an abandoned night visual approach from which the captain elected to climb and turn into a 3,000ft downwind leg to make a second approach. In the latter case, the changes in attitude and power were less dramatic, but as the captain advanced the power and began the climbing turn to the left over the night sea, he would have lost the airfield and town lights and should have transitioned fully to flight instruments. He didn’t. The aircraft described a shallow spiral into the dark water.

Somatogravic illusion makes instrument flying essential, but more difficult because of the need to reject the balance organs’ misleading input. A clear natural horizon in daylight completely overcomes those misleading feelings, and although the flight instrument panel – especially in modern flight-decks – provides an intuitive visual display, it is artificial and still not as compelling as the real thing.

But there is a long list of LOC-I accidents in the last two decades that involved more subtle sensory inputs resulting in pilot disorientation, and everybody died just the same.

Think of the old expressions associated with instrument flying skills.

First, there is its antithesis: “Flying by the seat of your pants.” Anybody who believes that is possible in IMC or on a moonless night is fated to die.

Then there is the original name for the skill: “Blind flying”; that was in the days before the artificial horizon was invented, when the airspeed indicator, altimeter and turn-and-slip indicator sufficed for accurate flying, possibly assisted by a vertical speed indicator.

Further clues as to the fascination – even mystery – surrounding early blind flying skills are the descriptions of what it feels like when things are going wrong: “The Leans” described the situation in which your perception of what the aircraft is doing is not what the instruments tell you. Finally there is the extreme example of “The Leans”: Americans used to call it “vertigo”, Europeans “disorientation”. That is when your senses are screaming at you that the situation is not what your flight instruments say – you don’t even know which way up you are.

Nothing has changed just because aircraft now have LCD displays.

It is time to go back to basics, to re-discover pride in precision manual instrument flying, and regain that skill which no pilot truly believes s/he has lost, but which automated flying has stolen away silently, like a thief in the night.

PS: Good blind flying is not a stick-and-rudder skill, it’s a cognitive skill.

 

 

 

 

 

Muilenburg: Returning Max to service ‘will be an international decision’

Boeing CEO Dennis Muilenburg says the successful return to service of the company’s 737 Max series depends on international consensus among the many national aviation authorities (NAA) that will see the aircraft operating in their countries.

Not just the US FAA.

As a reminder, the 737 Max series fleet was grounded in March as a result of findings from the investigations into to the Lion Air and Ethiopian Airlines fatal crashes, respectively in October 2018 and March this year.

Speaking this week at Boeing’s Seattle Delivery Centre, Muilenburg declined to predict a return-to-service date, explaining: “Dates are uncertain because we are going for a global recertification.” That means unanimity – near or absolute – has to be achieved.

Boeing aircraft being prepared for delivery at Boeing Field, Seattle

He emphasised the point: “If we do not coordinate this [return to service] we may see some disaggregation, and I don’t think that’s a future any of us wants to see.”

Muilenburg is confident the combined hardware and software changes Boeing has developed for the Max will satisfy the FAA and the multinational Joint Operations Evaluation Board (JOEB).

The primary causal factor of the Lion Air crash was erroneous triggering of its manoeuvring characteristics augmentation system (MCAS) by a faulty angle of attack (AoA) sensor, according to the Indonesian final accident report. It is at the MCAS that Boeing’s efforts have been directed.

More on MCAS later.

Boeing test pilot and VP Operations Craig Bomben, who flew the 737 Max first flight and has coordinated development activity on the type since the accidents, described the essential difference between the original MCAS and Boeing’s proposed replacement: “We’ve moved from a very simple system to an intelligent system.”

In both the accidents MCAS – triggered by a faulty or damaged AoA sensor which wrongly indicated a high AoA – reacted by providing nose-down stabiliser rotation that took the pilots by surprise. They did not understand the reason it kicked in. Their efforts to reverse the strong nose-down pitch did not succeed, and because both these events occurred just after take-off, the loss of height quickly resulted in impact with the surface.

Bomben said the new “intelligent” system has two AoA sensors instead of one, and if their readings differ by 5.5deg or more, MCAS is not triggered at all.

But if it is correctly triggered, the system now “operates only once per AoA event”, according to Bomben, and when it does trigger stabiliser movement, it memorises how much displacement has taken place, so if it were triggered again it would take account of existing stabiliser displacement and will not apply more than a safe cumulative limit.

But why is MCAS – which is unique to the Max – required at all? Boeing insists it was not fitted as an anti-stall system, because the aircraft already has stall warnings and stick-shakers.

The purpose of fitting MCAS, Bomben explained, was to compensate for a slight change in the low-airspeed aerodynamics of the 737 Max compared with the NG.

MCAS was only designed to trigger in an unlikely (but obviously possible) combination of circumstances that can cause the aircraft’s centre of lift to move slightly further forward, altering the weight-balance equation. It only happens when the Max is at low airspeed with the flaps up, and is being flown manually.

At low airspeed (200kt or thereabouts) – and flapless – the aircraft would be at a high angle of attack and close to the stall. FAA regulations require that one of the cues to the pilot of the approaching stall is that there should be a linear increase in the required column force versus displacement response.

In the Max, however, at a certain point in this sequence the centre of lift shifts forward a little, providing a slight nose-up pitch force, therefore the stick force does not continue to increase, so MCAS is designed to kick in with some nose-down trim to restore the linear increase.

If MCAS doesn’t kick in, the aircraft is still easily controlled without it, but the required progressive stick-force cueing is lost.

In technical and regulatory terms, MCAS seems to be a lot of fuss for very little purpose, but the painful fact is that the original MCAS played its part in bringing down two aeroplanes and killing 346 people.

Muilenburg’s confidence in the fix is, so far, based on more than 100,000 hours of development work on the new solution, plus 1,850 flight hours using the new software, 1,200 hours of refining the results in the simulator, and 240 hours of regulatory scrutiny in the simulator.

Meanwhile, if Muilenburg cannot predict when the world will approve the 737 Max’s return to the air, what is happening to its production at present? The aircraft had won more than 5,000 orders, and fewer than 400 have been delivered.

The Max series, despite the grounding, continues to roll off the production line at Boeing’s Renton plant near Seattle, at a rate of 42 per month. The factory is capable of turning out 57 a month, but Boeing is keeping the rate lower for now. Despite this, Renton has seen no staff layoffs, says Boeing.

The completed aircraft, however, go into storage at Moses Lake or San Antonio desert sites, because the manufacturer’s own sites at Renton, Everett and Boeing Field are full.

Muilenburg said every 737 Max grounded or in store awaiting modification will have an individual entry into service programme, and that in the meantime the engines, systems and cabin of all the aircraft are regularly being run and maintained.

But will they still have that “new plane smell” when the airlines take delivery?

A Max in production at the Renton plant, its unique split winglet close to the camera

 

The Max crux

Boeing, the FAA, and national aviation authorities (NAAs) from several other countries, met in Dallas on 23 May to consider the future of the 737 Max series of aircraft.

It is impossible to overstate how important this meeting is. The way civil aircraft manufacturing does business, not just in America, but all over the world, is under scrutiny.

Detail gradually emerging from Boeing and the FAA following the two 737 Max fatal crashes has upset such basic assumptions about the way modern aviation works that industry veterans – whose initial reaction was that this was just a case of finding a fix and getting the Max airborne again – are , only now, fully realising it’s not.

Like the Looney Tunes cartoon characters who ran over a cliff they didn’t know was there, we didn’t begin to fall until we looked down.

Let’s examine the proposal that all airliners nowadays are massively computerized, so adding some digital controls to the good old 737 to make it a Max is just bringing the 737 marque up to date.

After all, digital controls work on other types like Airbuses and Boeing’s own 777 and 787, and they are safe, so why not on the 737?

Back to basics.

All modern commercial airliners are supposed to be designed, in the first place, so they fly easily and intuitively, and have a natural aerodynamic stability within their flight envelope. That should hold true with or without computer control.

Designing an aircraft to be fly-by-wire, rather than conventionally controlled, can provide additional safeguards, but the airframe itself should still fly naturally.

Applying a digital solution to an airframe-related flight characteristic that is undesirable is a different matter entirely; but that is what Boeing chose to do when it installed the Manoeuvring Characteristics Augmentation System (MCAS) in the new Max.

The fact – revealed by the fatal accidents – that the MCAS could be triggered when it was not needed, and what consequences might follow its triggering, appears not to have been examined in any depth by Boeing or the FAA.

The fundamental questions for the FAA – and the foreign NAAs- are these: is the Max, as a simple airframe without digital corrections, sufficiently stable within its flight envelope to satisfy the regulators it is worthy of certification?

If not, is a digital fix sufficient to cover the undesirable flight characteristics lurking in a corner of its flight envelope? How reliable does the fix have to be to win approval?…and how can its reliability be proven?

For three decades the aviation world has agreed to operate a regime whereby the NAAs in countries where aircraft are manufactured all use the same standards when they certificate a new aircraft. So when the FAA certificated the 737 Max, the rest of the world accepted the FAA’s judgement and did not insist – as in the bad old days of the 1970s and before – on re-certificating it country by country.

What if, in this case, the FAA re-certificates the MCAS-modified Max, but foreign NAAs do not? The European Cockpit Association today has called on the European Union Aviation Safety Agency to scrutinize any FAA approvals, and EASA has pledged to do so. Is this “back to the bad old days”?

At the end of the Dallas meeting Boeing had this to say: “We appreciate the FAA’s leadership…in bringing global regulators together to share information and discuss the safe return to service of the 737 MAX….Once we have addressed the information requests from the FAA, we will be ready to schedule a certification test flight and submit final certification documentation.”

Industry speculation as to when the FAA will be ready to approve return to service varies massively, from a week to many months. These seers also seem to be preparing themselves for disagreement between the FAA and foreign NAAs.

This is the point at which you dare not look down.

 

Suddenly I see…

Today, air traffic control officers (ATCOs) on each side of the North Atlantic can see the aircraft they are controlling as they fly between Europe and North America.

It is almost impossible to convey the huge significance of this boring and apparently obvious piece of information, because most people don’t know that – yesterday – the same ATCOs couldn’t see the aircraft they were responsible for. They never had been able to see them, because the machines were outside radar range.

When flying between North American and Europe, until now aircraft of all kinds have always been invisible to air traffic control from the time they were about 350km off the coast on either side.

Under yesterday’s system, ATCOs knew approximately where each aircraft was because the pilots reported their position, their height and an estimate for the next reporting point every 15min or so. This worked safely because aircraft were painstakingly released into their pre-cleared, one-way oceanic tracks at specific heights, time intervals, and speeds, so they would maintain separation vertically and horizontally.

That system is a well-tried air traffic management (ATM) technique known as procedural control, and most of the world will continue to control air traffic procedurally over almost all oceanic and wilderness areas for some years yet.

In fact only 30% of the earth’s surface has radar coverage enabling aircraft surveillance for air traffic management (ATM) purposes.

But now, a new global constellation of 66 low-earth-orbit smart satellites – launched over the last decade by satcoms company Iridium Communications – each carries a device that links aircraft ADS-B datalink signals to ATM centres. Aircraft-mounted ADS-B (automatic dependent surveillance – broadcast) streams information about the aircraft’s position, height and much more. This enables ATCOs to track the aircraft in real time, with a radar-like update rate of 8 seconds.

Here’s the history (this announcement should really be preceded by a trumpet fanfare!): US-headquartered communications technology company Aireon yesterday announced that its space-based air traffic surveillance system was switched on, and active surveillance trials involving ANSPs (air navigation service providers) Nav Canada and UK NATS have begun on the busy North Atlantic routes that each manages from its respective oceanic base either side of the sea.

Aireon CEO Don Thoma was able to boast that “For the first time in history, we can surveil all ADS-B-equipped aircraft anywhere on Earth.”

Well, it’s true that they are set up to do so, but not all the world’s ANSPs are ready for it yet. Those who are ready include Nav Canada and NATS, but also the Irish Aviation Authority, Italy’s Enav, and Denmark’s Naviair.

The European Aviation Safety Agency (EASA) is in the process of certificating the provision – by Aireon – of space-based surveillance over the whole continent. That will be another first: the provision of surveillance capability by an organisation that is not an ANSP nor the military.

Others will follow.

What the Max story says about safety oversight today

Yesterday the US Federal Aviation Administration joined most of the rest of the aviation world in grounding the Boeing 737 Max series of aircraft, the very latest version of the established 737 series. What took it so long?

Having entered service in May 2017, by early March this year the Max had suffered two fatal crashes within five months. This is extraordinary for a new commercial airliner today.

Evidence from the preliminary report on the earlier of the two accidents suggests a technical failure precipitated it. The first event, in October 2018, involved a nearly-new 737 Max 8 belonging to Indonesian carrier Lion Air. It crashed into the sea near Jakarta within about 10min of take-off. The second accident, on 10 March this year, involved an Ethiopian Airlines aircraft of the same type, and it plunged into the ground within six minutes of take-off from Addis Ababa. Pilots of both aircraft radioed that they were having trouble controlling the aircraft’s height, and this was evident on flight tracking systems.

The FAA issued its grounding order on 13 March. This was three days after the Ethiopian crash,  two days after China, Ethiopia and Singapore had banned Max operations, and a day later than the influential European Aviation Safety Agency – and many other states – had done the same.

Does this demonstrate that there are different safety standards – or safety philosophies – in different countries? Or does it suggest that the relationship – in this case – between the safety regulator and the manufacturer is too close?

On 12 March, resisting calls to ground the aircraft, the FAA said: “Thus far, our review shows no systemic performance issues and provides no basis to order grounding the aircraft.”

The next day it stated: “The FAA is ordering the temporary grounding of Boeing 737 MAX aircraft operated by U.S. airlines or in U.S. territory. The agency made this decision as a result of the data gathering process and new evidence collected at the site [of the Ethiopian crash] and analyzed today. This evidence, together with newly refined satellite data available to FAA this morning, led to this decision.”

The safety principle behind aircraft design, for more than half a century, has been that all systems should “fail safe”. This means that any one critical system or piece of equipment, if it fails, will not directly cause an accident. This is achieved either by multiplexing critical systems so there is backup if one of them fails, or by ensuring that the failure does not render the aircraft unflyable.

The preliminary report from the Indonesian accident investigator NTSC suggests that a factor in the sequence of events leading to it was a faulty angle of attack (AoA) sensor. This device, says the report, sent false signals to a new stall protection system unique to the Max series of 737s, known as the manoeuvring control augmentation system (MCAS). According to the report, these signals wrongly indicated a very high AoA, and the MCAS triggered the horizontal stabiliser to trim the aircraft nose-down. Finally, the crew seems not to have known how to counteract this nose-down control demand.

The implication of the NTSC report – not the final verdict – is that the MCAS was not designed according to fail safe principles: a single unit failed, causing a software-controlled automatic system to motor the powerful horizontal stabiliser to pitch the aircraft nose-down, and it kept on doing this until the crew could not overcome the pitch-down force with elevator.

At that point disaster could still have been prevented if the crew had been familiar with the MCAS, or with the drill for a runaway stabiliser trim. But the MCAS would not have been expected to trigger at climb speeds during departure. The result was that in this case the crew failed to act as the final backup safety system.

In the months immediately following the Indonesian crash some pilot associations in the USA whose members operate the Max publicly claimed that there was a widespread ignorance among Max-qualified pilots of the very existence of the MCAS, and also many assumed that a runaway trim could be dealt with in exactly the same way as it was for all the earlier 737 marques. Actually the drill is quite different for the Max, as Boeing and the US Federal Aviation Administration (FAA) have pointed out. There is more detail on the MCAS in the preceding item in this blog – “This shouldn’t happen these days”.

Somehow, therefore, many 737 Max pilots in Boeing’s home territory had found themselves un-briefed on a system that was unique to the Max. They claimed lack of detail in the flight crew operations manual (FCOM), which described the system’s function but did not give it a name. US pilots who converted to the Max were all 737 type-rated and had flown the NG marque, but their conversion course to the Max consisted of computer-based learning, with no simulator time.

This ignorance among US pilots was soon corrected because the issue got plenty of intra-industry publicity, so if a US carrier pilot suffered an MCAS malfunction the crews would have known to apply the runaway trim checklist, and select the STAB TRIM switches to CUT OUT. Was this confidence about US crew knowledge the reason the FAA was able to maintain its sang-froid over grounding for longer than the rest?

On the other hand it is not a good principle to use a pilot as the back-up for a system that is not fail-safe.

In the 1990s there were several serious fatal accidents to 737s caused by what became known as “rudder hard-over”. This was a sudden, uncommanded move of the rudder to one extreme or the other, rendering the aircraft out of control, and unrecoverable if it happened at low altitude. The problem was ultimately solved by redesigning the rudder power control unit, for which there was no backup, thus no fail-safe.

If a Boeing product has a fault the responsibility is Boeing’s, but it is equally the FAA’s. The FAA is the safety overseer, and should satisfy itself that all critical systems are fail-safe and that the manufacturer has proven this through testing.

If America has an image it is that of the can-do, the entrepreneurial risk-taker. Why would Boeing or the FAA be different? One of the FAA’s stated values is this: “Innovation is our signature. We foster creativity and vision to provide solutions beyond today’s boundaries.”

The world has benefited from the USA’s risk-taking culture which has driven some aviation advances faster than they would have occurred in other more risk-averse cultures like that of Western Europe. An example of this is the massive extension of ETOPs (extended range twin engine operation) with the arrival on the market of the Boeing 777, which ultimately drove the four-engined Airbus A340 out of the market and influenced the early close-down of the A380 line. Boeing and the FAA took the risk together, and together they got away with it.

Is the 737 Max going to prove to be the one Boeing didn’t get away with? Time will tell.

But is certain Boeing will find a fix that will get the Max back in the sky. And although this episode, if it runs the course it seems likely to follow, will damage Boeing, the damage will be far from terminal. The company has an unbreakable brand name by virtue of being so good for so long, but trust will have suffered.

In the world at large, the art and science of safety oversight is changing dramatically. Technology is advancing so fast that the traditional system of close oversight by the regulator cannot work without stifling innovation, so “Performance-Based Regulation” (PBR) is the new watchword. Basically this means that the regulator prescribes what performance and reliability objectives a system or piece of equipment should meet, and the manufacturer has to prove to the regulator that it meets them. This is fine, providing that the regulator insists on the testing and the proof, and has the expertise and resources to carry out the oversight.

Although lack of oversight resources in the FAA seems unlikely, it would be a global disaster if it occurred. The same would be true of other national aviation agencies (NAA) in countries where aviation manufacturing takes place.

That risk of under-resourcing NAAs is a serious worry for the future, because all the signs are that most countries consider it a very low political priority, especially at a time of budget austerity.