Abstract 5B-DBY. During climbing the Captain reported a


Safety is one of the most important aspects of the aviation industry.

Breaking established rules or regulations can cause damage to equipment,
personal injuries, or even death. Based on the seriousness of these effects,
commercial airlines are working to dramatically improve their safety programs.

Aviation organizations like the EASA, FAA, ICAO investigate many accidents,
both major and minor, making recommendations or restrictions to improve and
keep air travel the safest mode of transportation in the world. This research
paper will analyze Helios Airlines flight 522 crash where a Boeing 737-300 lost
pressurization during flight and the crew and the passengers fell asleep due to
hypoxia with the aircraft ultimately crashing northwest of the Athens International
Airport in Greece. The investigators concluded that direct and latent causes
are to blame for the accident. In this case, the direct cause can be a review
of not following maintenance steps and missing flight crew emergency
procedures. The latent causes are: quality of the management, safety culture,
manufactures ineffectiveness regarding previous pressurization issues.

Following this accident, many recommendations regarding cabin pressurization
safety checks have been provided to the airline industry in an effort to avoid
this type of accidents in the future.








            Helios Airways was a low-cost
company based at Larnaca International Airport. On 14 August 2005, flight 522
operated by Helios Airways, departed Larnaca, Cyprus at 06:07 for Prague, Check
Republic. The aircraft was Boeing737-300 built 1998, acquired by Helios
Airlines on 16 April 2004 with registration number 5B-DBY. During climbing the
Captain reported a problem with a Take-off Configuration and the Cooling system.

A few minutes later no more contact with the crew. Greek air force sent two F16
to escorted flight 522 and inspected for any damage or fire on board. No
external damage or fire was noted and the aircraft was not responding to radio
calls (Arrubla, 2017). Also, passenger’s oxygen masks were deployed. At 8:50
due to fuel depletion the aircraft started decreasing altitude and thirteen
minutes later crashed 33 km northwest of Athens International Airport. After
the crash aircraft was totally destroyed and all 121 passengers and crew were
dead. Later on few human factors error were detected: Psychological,
Psychosocial, Hardware, Task and Environmental factors.

causes of the accident

            The issue with the airplane started
the previous day on 13 August 2005. When the aircraft arrived from London
Heathrow, the previous flight crew had reported a frozen door seal and abnormal
noises coming from the right aft service door. They requested a full inspection
of the door. The inspection was carried out by a ground engineer who then
performed a pressurization leak check (Salgunan, 2015). The investigators
concluded that the Aircraft engineer who performed this pressurization test
never put back the pressurization switch from manual to auto position how
should be during normal flight configuration. The maintenance documentation for
job completion did not specify exactly the step to set up the switch after
maintenance and the technician did not follow carefully the maintenance
procedures for closing the job task by Aircraft Maintenance Manual. When departed
for the next flight and increased the altitude the aircraft was not able to
pressurize the cabin due to position of the switch. Based on that issue warning
alarm showed and the passenger’s oxygen masks dropped. Unfortunately, the
passenger’s oxygen from the masks was only for twelve minutes. On this altitude
without a pressurized cabin, the oxygen is not enough for a breadth and
everybody fell asleep due to hypoxia. Only the flight attendant Andreas
Prodromou was awaked longer time with attempted to contacted the tower and
tried landed the aircraft safely but unfortunately without success. DNA
analysis on samples from the cockpit revealed that Andreas Prodromou was inside
the cockpit. This raised many questions about whether the flight attendant was
trying to save the plane or trying to deliberately crash the plane (Salgunan, 2015). 

            Before every departure, the crew
has procedures to prepare the aircraft for flight. Preflight and After takeoff
checklist guarantee safety flight without missing procedures. In flight 522 the
investigators concluded that the pilots did not follow this Preflight checklist
and that was the main reason for the accident. Under pressure, the Captain did
the preflight check by memory and missed to verified the position of pressurization
switch. Workload or level of training was the reason for incorrect completion
of the procedures. This Task factors affected the pilot’s performance. After
takeoff checklist also directs the flight crew to verified the pressurization
system configuration but unfortunately, in this case, was missed again. The
flight started with two missing procedures and the third one was even more
critical. During troubleshooting the crew never identified the warning message
and why was occurred. The aircraft continued to climb and made the situation
even more complicated. They did not check the pressurization switch position
independently of the instructions of the Air Traffic Controller to do that.

Psychosocial factor based on work environment caused stress fatigue and made
the pilots performed wrong decisions. Next direct cause was lack of
communication during contact with Air Traffic Controller. Language difficulties
between the Captain and the Helios Operations Centre, probably due to the fact
that the Captain spoke with a German accent and could not be understood by the
British engineer prolonged resolution of the problem, while the aircraft
continued to climb. Moreover, the communication difficulties could also have
been compounded by the onset of the initial effects of hypoxia (Arrubla, 2017).

Many mistakes were involved in this situation which presupposes to a fatal
final. The crew never followed the emergency procedures put their oxygen masks
or decreased altitude. This mistake was caused by Psychological factor and
especially from their complacency and not attention. Their awareness of danger
and control of attention was reduced. The pilots just keep troubleshooting the
issue without an idea what could be the consequences. This brought them to lack
of oxygen and fell asleep due to hypoxia. No alarm shows the pilots that the
oxygen masks have dropped in the cabin, and pilots mask needs to be manually
used. The pilots didn’t wear their own oxygen masks because they didn’t
consider this as a problem (Salgunan, 2015). Lack of oxygen is an Environmental
factor which had an extremely negative impact over the crew. Incapacitation of
the flight crew due to hypoxia, resulting in a continuation of the flight via
the flight management computer and the autopilot, depletion of the fuel and
engine flameout, and impact of the aircraft with the ground (Griffioen, 2009,

causes of the accident

            Besides the direct causes of the
accident with flight 522, the investigators also were found many latent causes.

Their conclusion started with the poor quality of management and safety culture
of the organization. Years before many errors were detected in Helios Airways
and recommendations were provided for fixing these issues. These steps would
help to improve the Safety rules of the company. There were organizational
safety deficiencies within the Operator’s management structure and safety
culture as evidenced by diachronic findings in the audits prior to the
accident, including: Inadequate Quality System; Inadequate Operational
Management control; Inadequate Quality and Operations Manual; Cases of
non-attendance of management personnel at quarterly management quality review
meeting (Ministry of Transport, 2006, p.157). The reason for corrective plans
to fix the issues delayed was the ineffectiveness of the aviation authorities.

The Latent causes made the first step of the accident creation, started years
ago. Day of the crash based on this latent causes followed by precondition
failures started the process of the accident. After a few more pilot’s
mistakes, the accident occurred with the active failure. Never any of this
factors do not have to be ignored. One factor brings another and creating a
chain of failure which increases the risk of an accident. After the crash, many
recommendations about safety procedures was issued. One of them was about
decreasing altitude if detect loss of cabin pressure. This procedure will help
everybody on board to bread normally if the pressurization system does not
work. The second recommendation was creating practical hypoxia training on all
cabin crew and make them more confident about what should be their reaction
during a loss of pressurization. During flight 522 crew members was absolutely
unprepared for such a situation and their reaction led to the fatal end. One
recommendation was addressed to the Republic of Cyprus and proving their
procedures for better carry out the aviation safety oversight functions. Until
this time the Government of the Republic of Cyprus never applied adequate
control over the company to performed the safety recommendations. If the
institution had their job done probably the craft of flight 522 will be

             Manufactures ineffectiveness
regarding previous pressurization issues is also one of the causes of the
accident. At this time the Pressurization issue alarm was not specified and
this equipment design confused the pilots and made harder for them to found
what was exactly the problem. In this case, the human performance is affected
by the Hardware Factor. After this accident, many safety actions were taken to
avoid this for the future. One of them changing the Aircraft Maintenance Manual
procedures for pressurization check and specified the step “pressurization mode
selector be returned to the AUTO position after the pressurization check”
(Ministry of Transport, 2006, p.155). Another big change was the structure of
Preflight and After Takeoff checklists. The pressurization system flight
configuration steps were made much clear and easier to be complete without
missing any of the procedures. Special alarm for the pressurization mode switch
was created for easier to found a fault with the pressurization system
operating. Boeing Company reconsiders the design of the Cabin Pressure Control
System controls and indicators so as to better attract and retain the flight
crew’s attention when the pressurization mode selector position is in the MAN
(manual) position (Ministry of Transport, 2006, p.161).


            Regarding this crash, many world
wise Aviation Organization took measures to prevent this kind of accidents in
the future. In the aviation behind any big changes stayed accidents and most of
them with victims. The Air transport is the safest in the world but when an
accident occurs usually have a multiple dead and that make this crash tragedy.

This case started from the negligence of followed the aviation safety
recommendations to not following the maintenance procedures and crew human error
factors. Like this and many other accidents always were involved multiple
factors. In flight 522 investigators concluded issues with documentation,
trainings, procedures and lack of communication. When everything became together
appears big safety gap and a precondition for an accident. To avoid this the
procedures must be following strictly and every air company needs to be responsible
about the Safety rules.