All of us heard that Aviation is the safest Transportation way. That is basically true but, if 94% of accidents happen while on ground or near to ground, we should think that some flight phases have a risk level to be studied.
It’s true that some activities bring an intrinsic risk and Safety means balancing acceptable risk level .vs. efficiency. Aviation is in that common situation but it has its own problems: The lack of an external assessment made the safety-related decisions to be inside a little group of manufacturers, regulators and operators. Consumers listen the mantra “Aviation is the safest Transportation way” but they cannot know if some decisions could drive Aviation to leave that privileged position.
A little summary of technology evolution in the big manufacturers could show how and why some decisions were made and how, in the best possible scenario, these decisions meant losing an opportunity to improve safety level. In the worst one, they should mean a net decrease in safety level:
Once jets appeared, safety increased as a consequence of higher engines reliability. At the same time, navigation improvements like ground-based stations (VOR-DME), inertial systems and, later, GPS appeared too.
However, at the same time that these and other improvements appeared, like making zero visibility landings possible, some other changes whose contribution could be considered as negative appeared too.
One of the best known cases is the engines number, especially in long haul flights. Decades ago, the standard practice for transoceanic flights was using four engine planes. The only exceptions were DC-10 and Lockheed Tristar with three engines. However, in places like U.S.A., long flights where, if required, planes could land before their planned destination, were performed by big planes with only two engines.
Boeing, one of the main manufacturers, would use this fact to say that engines reliability could allow transoceanic flights with twin planes. Of course, maintaining two engines is cheaper than maintaining four and, then, operators should have a strong incentive to embrace the Boeing position but…can we say that crossing an Ocean with two engines is as safe as doing it with four engines, keeping the remaining parameters constant?
Intuition says that it’s not true but messages trying to oppose this simple fact started to appear. Among them, we can hear that a twin modern plane is safer than a four-engine old plane. Nobody said that, if so, the parameter setting safety level should be how old the plane was. Then, the right option should be…a modern plane with four engines.
Airbus, the other big manufacturer, complained because at that moment did not have its own twin planes to perform transoceanic flights but, some time after, they would accept this option starting their own twin planes for these long haul flights. This path –complain followed by acceptance and imitation- has been repeated regarding different issues: One of the manufacturers proposes an efficiency improvement, “its” regulator accepts the change asking for some improvements and the other manufacturer keeps complaining until the moment they have a plane that can compete in that scenario.
In the specific case about twin engines, regulators imposed a rule asking the operators to keep a certain distance from airports that could be in their way. That made twin planes design longer routes and, of course, that meant time and fuel expenses. However, since statistical information showed that engines reliability is very high, the time span allowed to fly with only one engine working while loaded with passengers was increasing until the present situation. Now, we have planes that are certified to fly with only one engine working until arriving to the nearest airport…assuming that it could be 5 hours and a half far. Is that safe?
We don’t really know how safe it is. Of course, it is efficient because that means that a twin engine certified in that way can fly virtually through any imaginable route. Statistics say that it’s safe but the big bulk of data about reliability does not come from laboratories but from flying planes and that’s where statistics could fail: Engines reliability makes that big amount of data come from flights where both engines have been working in uneventful flights. We can add that twin planes have more remaining power than four-engine planes due to the exigence that, if an engine fails after a moment during take-off, the plane has to be able to take-off with only one engine. Of course, the four-engine plane has to be able to perform this action with three engines, not with one.
In other words, during cruise time, the engines of a twin plane work in a low effort situation that, of course, can have a favorable impact in reliability. The question that statistical reports could not address because of lack of the right sample should be: Once one engine failed, the remaining one starts to work in a much more exigent situation. Does it keep the same reliability level that it had while both engines were working? Is that reliability enough to guarantee the flight under these conditions for more than 5 hours? Actually, the lack of a definitive answer to this question made the regulators to ask for a condition instead: The remaining engine should not get out of normal parameters while providing all the required power to keep the plane airborne.
At least, we could have some doubts about it but, since the decision was made among “insiders” without any kind of external check, nobody questioned it and, nowadays, the most common practice at boarding a transoceanic flight, is doing it in a twin plane. We will attend to the masks and lifejackets show but it’s unlikely that some could say:
“By the way, the engines in this plane are so reliable that, in the very unlikely event that one of them fails, we can fly with full safety with the remaining one until reaching the nearest airport, no more than 5 hours and a half far”.
How many users are informed about this little detail with they board a plane with the intention of crossing an Ocean? This is only and example because it’s not the only field where improvement followed by complains and acceptance was the common behavior.
Engines number is an issue especially visible –for obvious reasons- but a similar case can be observed in matters like codkpit crewmembers decrease or automation. Right now, there is not a single passengers plane from any of the big manufacturers bringing flight engineer. In this case, Airbus was the innovator in its A310 model and, like in the engines issue, we could ask if removing the flight engineer has made Aviation more or less safe.
Boeing was the one complaining in this case but…it happened to be designing its models 757 and 767 that, in the final configuration, would be launched without a flight engineer.
Is a flight engineer important for safety? Our starting point should be a very easy one: The job of a pilot does not know the concept of “average workload”. It goes from urgencies and stress to boredom and viceversa. In a noneventful flight overflying an Ocean and without traffic problems, there are not many things to do. The plane can fly without a flight engineer and even without pilots. They remain in their place “just-in-case”, that is, in a situation quite similar –with some differences- to the one we can find in a firemen place. However, when things become complex, there is a natural división of tasks: One of the pilots flies the plane while the other one takes care of navigation and communications and, if there is a serious technical problem, they have to try to fix it…it seems that someone is missing.
This absence was very clear in 1998 in Swissair-111, where a cabin smoke situation should make a MD-11, without a flight engineer, crash. In a few moments, they passed from an uneventful flight prepared to cross Atlantic Ocean to a burning hell where they had to land in an unknown airport, to find the place and runways orientation, radio frequencies…while keeping the plane controlled, throwing fuel and trying to know the origin of the fire to extinguish it.
The accident research, performed by “insiders” did not address this issue. Two people cockpit was already considered as a given, even though another almost identical plane –DC10- with flight engineer could have invited them to make the comparison. Of course, nobody can say that having a flight engineer should have saved the plane but the workload that pilots confronted should have been far lower.
This issue was not addressed neither when a plane from Air Transatt landed at Azores islands with both engines stopped. That happened because they were losing fuel and a wrong fuel management made the pilots transfer fuel to the tank that was losing it. Should it have happened if someone had been devoted to analyze carefully fuel flow and how the whole process was working? Perhaps not but this scenario was simply ignored.
Flight engineers dissappeared because automation appeared and that started a new problem: Pilots started to lose skills for manual flying and it drove to a situation named “automation paradox”:
Automation gets an easier user interface but this is a mirage: A cockpit with less controls and cleaner from a visual scope does not mean that the plane is simpler. Actually, it’s a much more complex plane. For instance, every Boeing 747 generation has been decreasing the number of controls in the cockpit. Even though, newer planes are more complex and that’s how the automation paradox works:
Training is centered in interface design instead of internal design. That’s why we find planes more and more complex and users who know less and less about them. A single comparison can be made with Windows systems, almost universal in personal IT. Of course, it allows much more things than the old DOS but…DOS never got blocked. Unlike DOS, Windows is much more powerful but, if blocked, the user does not have available options.
The question should be if we can admit a Windows-like system in an environment where risk is an intrinsic part of the activity. The system allows more things and can be properly managed without being an expert but, if it fails, there are not options for the average user.
“Fly-by-wire” system was introduced by Airbus in commercial Aviation, with the Concorde exception, and it confronted complains from Boeing. We have to say that Boeing had a high experience in fly-by-wire systems because of its military aircrafts. Again, we find a situation where efficiency is bigger even though some pilots complain about facts like losing kinestesic feeling. In a traditional plane, a hand on the controls can be enough to know how the plane is flying and if there is a problem with speed, center of gravity and others. In fly-by-wire planes, by default, this feeling does not exist (Boeing kept it in its planes but, to do so, they had to “craft” the feeling since the controls by themselves don’t not provide it).
This absence could partially explain some major accidents, labeled “Human Error” or “Lack of Training” without anybody analyzing what features of the design could drive to an error like, for instance, a defective sensor triggering an automatic response without the pilots knowing what’s going on.
What is the situation right now? If we check the last planes from the big manufacturers, we can get some clues: Boeing 787 .vs. Airbus A350. Both are big twin and long-haul planes, there is not a flight engineer, they are highly automated and they both have fly-by-wire system. Coincidence? Not at all. Through a dynamic of unquestionned changes agreed by insiders and without knowledge by the consumers, the winner will be always the most efficient solution. Then, both manufacturers finished with two models that share a good part of the philosophy. There are differences –electric .vs. hydraulic controls, feeling .vs. no-feeling from the controls, more or less use of composite materials, lithium .vs. traditional batteries…- but the main parameters are the same.
Issues that were discussed time ago are seen as already decided. The decision always favored the most efficient option, not the safest one. Could that be changed? Of course, but it’s not possible if everything keeps working as an “insiders game” instead of giving clear and transparent information outside.
We should understand too the position of “insiders”: A case like GermanWings was enough for some people -like NYT- to question the plane before knowing what really happened. A few days ago, we had an accident with a big military plane manufactured by Airbus and some people started already to question the safety of a single manufacturer…perhaps someone near to the other one?
Information has to flow freely but, at the same time, many people make a living from scandal and it’s hard to find the right point: Truth and nothing but the truth and, at the same time, deactivate the ones who want to find or manufacture a scandal. Nowadays, the environment is very closed and in that environment efficiency will have always the upper hand…even in cases where it shouldn’t. By the other side, we have to be careful enough to address real problems instead of invented ones. The examples used here can be illustrated not only with the referenced cases but with some others whose mention has been avoided.