Arnold Sten wrote:
Those four plane crashes were, in my opinion, not accidents, but
deliberate and pre-meditated acts of suicide and murder. To me, that
would explain why those did not make the list.

Perhaps that Cypriot 737 that crashed in Greece should be considered an
important one. Not because of failure of pressurisation system, but
because the politicians, after 9-11, mandated a hurried implementation
of the locked cockpit door system which proved fatal in the Cypriot 737
crash since the remaining conscious crewmember was prevented from
entering the cockpit to save the situation until the door unlocked when
fuel ran out, but by then, it was too late.


There is also the issue of aircraft wiring. It wasn't a single
accident/crash that changed aviation, but rather realisation after a
number of incidents that aircraft wiring was a big problem. And in the
case of the UA 747 near Hawaii, the conclusion was changed years later
from human error to faulty aircraft wiring. TWA800 and SR111 were the
more obvious accidents.


The early A320 problems also showed that FAA and other certification
agencies had antiquated testing procedures that did not ensure the
software on an aircraft was reliable. Most of the A320 problems did not
result in a crash, but still showed that the aircraft was put into
service with less than acceptable software quality which should have
been spotted before the aircraft entered commercial service. Aircraft
certification tests were revised and subsequent aircraft introductions
were far more reliable.


I'd have to say though that Comet was probably the biggest one since it
made engineers realise that pressurisation cycles affect aircraft
structure and that has been a major impact on all subsequent aircarft.