Can I just clear up one thing?......'blame'.
This is a word that gets my hackles up a little.
True aviation professionals should rarely allocate 'blame' - if ever.
No pilot, crew-member, ATC contoller or engineer ever goes to work wanting to risk lives or kill themselves (unless they are intent on sabotage). However, people are human and they make mistakes - but often those 'mistakes' actually make sense, in heat of the moment', to those that perpetrate them - this makes genuine error near enough 'blameless'.
Saying the cause of the accident was a lack of situational awareness, poor adherence to SOPs or processes etc, is no better than saying 'operator negligence' and places the 'blame' directly on the the last actor in the scene - this is something we should be getting right by now but many accident reports (and courts) just don't get it right....still - and this, after many years of Jim Reason and Sidney Dekker et al pointing the way to a better (and more cost-effective) safety culture.
What's more, in some countries like France and Greece, this flawed 'cause analysis' allows the legal vultures to have an 'in' on criminal negligence and litigation.
(This is apparent with the Helios engineer, who is the victim of a complicated political and moral morass that is often found in most legal systems.)
But if the 'final' fatal mistakes have any migitating circumstances - reduced training hours, culmulative fatigue/stress, group-think, deviant norms, finnancial/operational pressures or the like - then the accident rapidly becomes the result of a vulnerable organisational environment, reducing the 'blame' on the final actor(s). Most genuine errors have such mitigations.
In my opinion, the only time that 'blame' can be placed almost fully on an individual is when someone is told that a certain course of action increases the risks of an accident to unacceptable proportions - using common-sense and not just the statistics of probability/ALARP theory. This doesn't stop them making a 'command-decision' but if that person then carries on with their course of action without reducing/minimising the risks, then he/she is ultimately responsible for that decision and should be aware that 'blame' may fall on his/her head if things go pear-shaped. Such is the theoretical responsibility of command and why one 'in command' gets the extra money and fringe-benefits! This is also why responsibility should travel up the chain of command - while orders and sh!t flow the other way!
But, quite often, the person making the decision is senior and, as often as not, the means to reduce risks cost money and eat up their budgets and minimise their promotion prospects - so they often don't do what is right and people die. These senior people are the ones who should shoulder the majority of any 'blame'.
Of course, that is what should happen but it is difficult to pin this responsibility onto senior people; they employ expensive lawyers (as in a number of various preventable railway accidents) or, in the case of the military, are part of an apparently 'untouchable' cadre of senior-officers whom no-one has the cohones to 'out' - those within the cadre cannot speak out (or so they believe) because they depend on the collective protection of the cliquey 'star chamber' to guarantee their work and pensions; group-think and deviant norms in action!
T'was ever thus, I suppose but it doesn't make it right.
The only other time that blame can be allocated is when (to coin a phrase) 'there is absolutely no doubt whatsoever'. e.g. a plane crashes inverted, whilst trying to fly under a bridge or doing a fly-by and the CVR captures the pilots agreeing to do it for a lark!
In the Helios case however, the pilots, though obviously not as able as some, have a degree of mitigation (that creates some doubt) in that they had other equipment distractions that may have prevented them spotting their own error (not setting up the pressurisation panel correctly, nor spotting it during taxy and take-off), along with some possible trg and supervision deficiencies. Perhaps this is why they didn't do the obvious thing (to us, in the comfort of our own homes) and level off at FL100 - but we will never know exactly why, sadly. Ultimately, they paid the highest price for their errors - and this, if nothing else, serves as a stark warning to all others who fly still. Total 'blame'? I'm not so sure.
Also, the warning horn was not of the best design (this doesn't then 'blame' the manufacturer immediately but it is something that should have been designed out as no-one, apparently, spotted this latent error - certainly, I wasn't aware of it when flew the B737 - I don't remember it being taught on the CBT either. OTOH, it might be a different matter if this circumstance had been specifically warned of (to Boeing), prior to this accident.....).
It is, however, plainly mad to almost-solely 'blame' the engineer for his one minor error before the crew made theirs - and even his 'error' is debateable iaw manuals etc. Godness knows how many mitigations he has for this and any lawyer worth his salt should be able to argue his case - expensive. Or just that he never goes to Greece again - the latter is the cheaper option and ultimately more agreeable to one's constitution - Greece is a depressing place at the moment!
"Blame? Only in extremis". I say.
(Mind you, there are few well-known senior RAF officers, as yet to accept their blameful moral responsibility, who should go their graves burdened by this guilt. I am of the opinion that it will catch up with them one day.
It is, however, never too late to repent - it would do the world of aviation safety great good for them to publicly accept they got it wrong - a true legacy - not just a row of tin medals on a shabby, faded uniform - left to gather dust in an attic or museum.)