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Comment by k1t | Hacker News Reader

Is there really a difference though?

To me a "trigger" is the initial event that begins a sequence. Isn't that also a "root cause"?

Since everything is connected to everything else, it seems like the point that you decide is the "root" is fairly arbitrary.

It seems you could easily conclude that the root cause was that the runway wasn't cleaned/inspected often enough. Or that the departures were scheduled too close together, preventing such an inspection, etc..

If anything I would say the root cause was the piece of engine cowl falling from the preceding flight - since that seems to be the first thing that "went wrong" in the process.

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Debris on the runway is something to be expected in rare cases, given how many flights there are a day it's just a matter of time until it happens.

As such the problem is an air plan which is designed in a way too prone to cause (too) fatal accidents in certain "rare but guaranteed to happen at some point" situation.

But in the end if you say both are trigger which together lead to the catastrophe or one is a trigger and another is the root cause is indeed irrelevant.

The problem is if you do something I will call trigger analysis but refer to root cause analysis treating it as if it gives you the root cause it can very easily to situations where you fix one of the problems but not all, and potentially not even the biggest problem.

I.e. you make it slightly less likely that there is debris on the runway but you don't fix the problem of the airplane being too prone to certain kinds of catastrophic failure.

If I said 'screw you', and that cause you to flip out and kill everyone around you, you couldn't say the root cause was me saying 'screw you'. The root cause might be childhood trauma, extreme emotional imbalance, irrational thoughts, etc. The statement 'screw you' was the trigger.

Similarly here, a trigger might be uploading a photo to FB, but the root cause of an issue might be a bug in encoding JPGs.

One approach to this is the "Five Why's" approach, wherein you ask "why" five times. eg,

Q1: Why did the plan explode?

A1: The engine cowling fell into the engine

Q2: Why'd that happen?

A2: The tire exploded and damaged it.

etc etc.

Obviously the number 5 is arbitrary and not always applicable, it's just a heuristic to get to something "root-ish" without getting to ridiculous distant things like "the laws of physics prevent two objects from inhabiting the same position in space-time".

More generally, defining something as root vs. not is somewhat of a judgement call. Usually you try to find something that will prevent future problems of this sort and call it the root cause. Ideally something that your organization can mitigate with a reasonable time/cost.

Note that the actual mitigation is a separate question. If runway debris is the root cause, then one mitigation is reworking the fuel system. Another would be using tougher tires. Perhaps another would be adding a shield between the tires and the aircraft body. Another might be an automated runway monitoring system that detects debris. etc.

A literal trigger is a lever that fires a gun. A figurative trigger is some event that sets in motion a cascade of events that occur in rapid succession. The root cause of firing a gun would probably be analogous to loading the chamber with a live round. Which may have occurred hours, days, months, etc before the trigger was pulled.

I think the distinction is that the "trigger" relates to a particular instance of failure, whereas the "root cause" relates to a class of failures.

> Is there really a difference though?

yes.

> To me a "trigger" is the initial event that begins a sequence. Isn't that also a "root cause"?

no. root causes are irreducible, hence the word "root".

if someone is endlessly trained for an event and then fails at game time, its probably a root cause. people make mistakes that cannot be avoided (this is why defense in depth is a thing)

if the training program is a 5 second sentence before the event, the persons mistake is not the root cause, its the training program.

To me the placement of the tanks or lack of protection would be the root cause. Because this failure could have been triggered by any other debris as well. So the root cause is the thing that If you fix it, it fixes the problem in a fundamental level.

I'm surprised nobody brings up swiss cheese theory here.

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