I would also point out they were already using tugs to guide the Dali safely out of it’s berth. So it would involve adding another 15 minutes of tug time to the ship’s operating expense.
They’re damn lucky this was at a time of road construction at night. There was a natural reduction of traffic and it already had police at both ends to ensure traffic safety. Had this happened at rush hour there would have been a much greater number of cars on the bridge with no police at hand to immediately shut it down.
I haven’t made any claim here that needs support, whereas you’ve suggested that tugs provide an adequate degree of reliability. I’m asking you to explain why you think that’s enough.
There is your problem. There is no such thing as a flawless design. There is no such thing as 100٪ No matter what you do, failure is always a possibility.
That’s only a true statement taken to infinity. But history has shown engineering flaws that were far from the financial side of infinity that caused great financial loss and death.
Do you think the Dali was without flaws that could be addressed at nominal financial cost?
I think that neither you nor I have anywhere near the information necessary to answer that question. Do you have privy to information that the rest of us don’t?
Besides the over a billion in damage and 6 dead people. No. Is that a criteria when posting? Do people have to be certified engineers with complete structural designs at hand before making a statement?
No, you can make whatever ill-informed statements you wish about why the accident happened and how it should have been prevented. I don’t know why engineers spend years getting an education and more years learning their trade when they could just listen to you.
To insist that you are right and everyone else is wrong? Yes. Maybe not a degree in engineering, but some experience that you can bring to the discussion.
Me, personally? As a programmer, I have been involved in decisions where we had to balance time/cost vs. potential problems.
I don’t know what the actual probability of this happening was, but I suspect it was nearing 0
If you look at aircraft, the multiple redundant systems have flaws requiring corrective action which are hopefully found before a catastrophic event, but not always.
The field of risk assessment and reliability is constantly changing; the industry is literally in a phase of examining the regulations and proposing overhauls to the existing regulations and guidance to enhance hazard assessment and system safety analysis and I’m anticipating a reckoning on the rules related to changed products.
It’s far from perfect, even if the threshold for “extremely improbable” events is 1x10^(-9) events per flight hour. Somehow, they still happen.
Read AC 25.1301. Read the Arsenal draft, if you can get it. Read this NPRM. You might begin to understand the complexity of the thing.
I have no reason to think maritime engineering standards don’t have similar requirements and similar overhaul as time goes on and events happen.
Of course money comes into play, but there are standards and thresholds to be met by engineers too.
And what is the probability of the engine also failing? It’s started using compressed air which is created by electrically driven pumps. They have X many attempts and then the compressors have to recharge the tanks that start the engine. The compressors are driven by the generators which failed.
FWIW the backup flight control systems on every big aircraft I’m familiar with have significant limitations on control authority and maneuvering capability. Even the powered ones when powered by backup pumps. And even more so for the fully manual backup control systems on the ever-fewer designs so equipped.
There are always malfunctions which overwhelm all the defenses in depth.
You’re right in the meta level that modern world-wide commercial ocean shipping practice and regulations demand far less redundancy and far less real-time-responsive redundancy than is common in world-wide commercial aviation. There’s simply no comparison as to the quality and stringency of the standards and their enforcement.
Until that changes stuff will keep happening in harbors, waterways, and the open sea. Dali specifically is a rather new ship that seems to have been in rather good condition and well-handled both before and during the mishap sequence. Sometimes shit just happens.
The mere fact a mishap occurred is not proof positive that corrective measures are necessary. It is proof positive that a thorough investigation should be done and any findings be added to the list of collective findings of all prior mishaps. And then that collective be used to guide future policy changes and priorities for action. Guided by both financial and technological feasibility as well as probability of recurrence and severity of consequences.
That last paragraph of course being exactly what is going on now with this and every other transportation mishap in most of the civilized world.
ISTM if there is any lesson for the world to learn from this event it’s that any bridge that can’t take a head-on collision from a modern-sized fully-loaded ship should be closed to road traffic tomorrow until a sturdier replacement can be built. Clearly the total number of such bridges and their total cost is far less than the cost of replacing literally every tanker and freighter in service; all of which lack the basic redundancy measure of two independent engines.
The probability of the engine failing is a factor in the probability of the event.
If it had failed just a few minutes earlier, or later, it would have been a non-event.
What percentage of it’s projected trip was it in just the right spot to hit the bridge?
There are certainly maritime standards to be met but they don’t appear to be on the same level as aviation. This was a single screw ship and the propeller is directly connected to the engine. They have to stop the engine and reverse it to reverse the propeller. There is a heavy reliance on the generators to back up this process and that extends to the rudder.
Yes, aviation events still happen and they are not immune to engineering flaws. Consider the A300 American Airlines crash (Flight 587) that resulted in the vertical tail shearing off. The FAA blamed the FO for excessive use of the rudder pedals but the NTSB came back and insisted Airbus change the design to limit rudder travel at higher speeds.
Because the failure analysis has very different outcomes; ships don’t generally fall out of the ocean, you know? Being dead in the water is a problem, but not really catastrophic. Being dead in the air…a bit more critical, I think (which is actually why there are rules about single engine or engine out operation …).
General aviation has safety thresholds that are much less strict than commercial aviation. Not nearly as much system redundancy and reliability on a single engine two seater as on a commercial passenger jet.
There’s a cost that goes with increased reliability, but it’s also balanced by probability and the effects of failure.
The odds of the cascading failures on the Dali were probably deemed to be miniscule, especially when considering location. That process of defining reliability and safety can, and should, be reviewed, but given the general performance of the industry it’s not like the original design was “wrong”. You can bump out the threshold to another order of magnitude of improbability, but you start getting impossible requirements.
I’m not disagreeing with you but as I pointed out there are mechanical flaws in aviation that exist within the standards of probability set forth. A ship with a single engine/propeller would have a higher risk than a ship with 2 propellers and 2 engines. Once at sea the probability of extensive damage/loss goes way down because time is on their side. Eventually they’re likely to get it restarted. In a port that changes.