Helios Airways Flight 522 - A Ghost Plane, In Which All Passengers Were Killed In A Mysterious Way Even Before The Plane Crashed

Last time we talked about a painful plane accident (2002 Uberlingen mid-air collision) in which the two planes collided at an altitude of 35000 feet, causing the death of all the passengers aboard the planes. But today we will talk about a plane accident in which all the passengers sitting in it had died mysteriously even before the plane crashed. The flight was named Helios Airways Flight 522, a passenger flight that was flying from Larnaca (Cyprus) to Prague (Czech Republic) with a stopover to Athens (Greece), on 14 August 2005, carrying a total of 121 passengers who all died under mysterious circumstances.

Flight and crash

Helios Airways Flight 522 takes off at 9:07 in the morning, the plane reaches an altitude of around 12040 feet but then suddenly an alarm system starts ringing. After checking this alarm, it has been revealed that this alarm is a take-off configuration warning but the big concern was that this alarm should have sounded on the ground. Well, what is this take-off configuration alarm and why should it ring on the ground, let's first know about it? The take-off warning system is basically a setup of some controls that are used in alerting the pilots for potentially-dangerous errors in an aircraft's take-off. But surprisingly, if there was some problem in the flight's take-off configuration then this alarm should have been sounded during the takeoff, not after going to an altitude of 12000 feet.

But before the pilot could find the answer to this question, the master caution alarm starts ringing, now what is this master caution alarm, let's understand it. Actually, aircraft have two such features, Master Warning Alarm, and Master Caution Alarm, which are indicated with yellow and red annunciator. If there is a problem in the plane, then the Master Caution alarm will start ringing, and once notified, the pilot may cancel the master caution. This alarm indicates attention and suggests that there is something wrong with the plane, It forces the pilot to find out the problem as soon as possible, and take appropriate action on it. But if the pilot is unable to detect the problem and does not take the right decision to sort out the problem at the right time, then in such a condition the master warning system starts ringing and this alarm keeps ringing until the problem resolves. Let's try to understand both these alarms through an example. Suppose if the engine of the plane is overheated then the Master Caution alarm will start ringing. If the pilot ignores it or does not take any action on it, then overheating will cause a fire in the aircraft engine, resulting in a Master Warning alarm to sound. Regarding the master caution alarm, we can say that it warns the pilot about the danger so that he can detect and fix the problem. In such a situation, we can guess that if this alarm is ignored then it can prove to be a great threat to the plane. This is the reason that both these indicators are placed in front of the pilots' seats so that in such situations, their attention can be drawn to it quickly.

Now let's talk about Helios Airways Flight 522, at first the take-off configuration alarm sounds in this plane, but before the pilot can understand the reason, Master Caution Alarm starts ringing. The problem in this plane does not end here, after a few seconds of this alarm the oxygen mask drops down, the oxygen mask drops only when the cabin pressure starts to decrease, causing the passengers to begin to suffer from shortness of breath. The oxygen masks automatically open either above or in front of the passenger and crew seats. Even after all this, the problems did not stop here, the plane's radio connection to the air traffic controller was also lost. Very strange incidents were happening with this airplane which was inconceivable to everyone. Therefore, to find out the status of flight 522, two F-16 fighter planes from the Hellenic Air Force were sent to the same location to locate flight 522. After reaching closer to Flight 522, the pilots of the fighter planes see that the first officer was slumped motionless at the controls and the captain's seat was empty and all the passengers were sitting on their seats with oxygen masks dangling in the passenger cabin, there was no movement in the plane. It seemed as if all the passengers had died. Then they saw a man walking in the cabin of the plane who entered the cockpit and sat down in the captain's seat. Then the plane suddenly turns to the left and starts falling straight down and finally, the plane crashed into hills near Grammatiko, 40 km from Athens. CVR records a total of five mayday messages. The incident that happened with Helios Airways Flight 522 was quite strange, therefore it has also given the title "The Ghost Plane".

After this incident a lot of questions started to arise, why the take-off configuration alarm rang in the altitude of 12040 feet, and why the Master Caution alarm started ringing soon after. And along with this the drop of oxygen masks, if there was not enough oxygen to breathe in the cabin then how all the passengers in the plane were sitting so quiet except a single man. The only Black Box or Flight Data Recorder could answer all these questions, although the cockpit voice recorder was damaged and it was recovered after a few days.

Investigation

Shortly after the investigation began, it was revealed that the Helios Airways Flight 522 had gone into maintenance a day before the accident. The pressurization leak check of the plane was also tested there, the maintenance department's engineer set its pressurization system to manual in order to carry out this check without requiring the aircraft's engines, but he accidentally left it in "manual" condition, however it needed to be reset to "auto" upon the completion of the test. 

The jet engine sucks the air and transfers some of the air into the cabin, and all passengers sitting in the cabin can breathe with the help of this oxygen. This process is known as Cabin pressurization, in which conditioned air is pumped into the cabin of the aircraft, to create a safe and comfortable environment for crew and passengers flying at high altitudes. The plane has pressure sensors that measure how much oxygen the passengers require and accordingly the air is automatically supplied in the cabin, creating such an atmosphere inside an aircraft similar to the land. The Carbon dioxide (CO2) being released by the passengers exits through the outflow valve located near the tail of the aircraft and in this way oxygen is supplied to the passengers in the proper amount. The outflow valve is automatically controlled by the aircraft’s pressurization system. But this can happen only when the pressurization system is set to "auto" if it is set to "manual" then it is the responsibility of the pilot to supply the appropriate amount of oxygen in the cabin. If we talk about all the planes in the world, the pressurization system in all the planes is set to "auto" by default, but if it is set to "manual" then it will give an indication with a green light on the plane's panel that it is in the "manual" mode, please set it on "auto" mode as soon as possible.

Now let's talk about the fault of Helios Airways Flight 522. The next day of maintenance Flight 522 took off at 9:07, as it is morning time, the sunlight was falling straight in the cockpit of this plane, and its brightness was not allowing the green light to make good visibility on the panel, indicating that the pressurization system of the plane is in manual condition. Now because the pressurization system of the plane was set in manual, therefore the jet engine was not supplying oxygen in the cabin. Then as the aircraft moved above 10000 feet, continuous air came out of the airplane cabin as the aft outflow valve was partially opened due to manual mode. And finally the pressure of the cabin went down and an alarm started to sound at 12040 feet of altitude. The pilot thought that this alarm was a take-off configuration alarm but this alarm was a cabin low-pressure alarm and the sound of this alarm was very similar to the take-off configuration alarm.

As we discussed above, the pressurization system is always set to auto and it is a very rare situation for aircraft that the cabin pressure decreases. That is why it is very rare that a low-pressure alarm is remembered in the mind of the pilot, and then in a few seconds the Master Caution Alarm starts sounding before the Flight 522 pilot can do something. Now as pilots are trained to pay close attention to Master Caution Alarm and Master Warning Alarm, that is why the focus of pilots shifted to only these two alarms during the whole incident and the low-pressure alarm was ignored by them. After some time, due to insufficient oxygen in the brain of the pilot, he could not able to make the right decisions, and slowly, the entire plane passengers began to lose their consciousness due to lack of oxygen in the cabin. The ATC was constantly trying to contact the pilot, but the pilot was unable to give an answer to the ATC due to insufficient oxygen. At the same time, two fighter planes reach there looking for this flight 522 and the pilots see that all the passengers in flight 522 are sitting quietly while a person takes a little oxygen from the passengers' oxygen masks and reaches the door of the cockpit. The pilot makes one last effort there and opens the cockpit door, but it was probably too late now and all the passengers inside the plane were suffocated. The pilots of both those fighter planes said that it was indeed a very painful time, but we could not do anything except waiting for their death.