Crash of Helios Airways 737 in Greece

August 14, 2005:  A Helios Airways 737 crashed in Greece today, with the loss of all 121 on board.

AP photo at Fox News

Initial reports have led to speculation that the crash followed a loss of cabin pressurization and that in turn, led to both pilots becoming incapacitated from hypoxia (lack of adequate oxygen in the blood stream and body tissues).  

While it is too early to conclude why a loss of cabin pressure might have occurred, or why the pilots may have been incapacitated (many first news reports are notoriously inaccurate), it does provide some justification for discussing how crucially important is the use and availability of supplemental oxygen, when cabin pressurization is lost.

On October 25, 1999, a chartered Learjet carrying famed golfer Payne Stewart, crashed near Aberdeen, South Dakota. That plane left Orlando, Florida, for Dallas, but contact with the flight was lost north of Gainesville, Florida, after ATC cleared the plane to climb to a cruise attitude of 39,000 ft. The airplane was intercepted by F-16 fighters and those military pilots observed that Learjet at close range.  They stated the forward windshields appeared frosted or covered with condensation. "They did not observe any structural anomaly or other unusual condition."  The plane continued to fly on its own for almost 1,400 miles, until it ran out of fuel and then spiraled to the ground and crashed.  All six onboard perished.

The NTSB finding:


The National Transportation Safety Board determines the probable cause of this accident was incapacitation of the flight crewmembers as a result of their failure to receive supplemental oxygen following a loss of cabin pressurization, for undetermined reasons.

In short, the plane lost its ability to maintain cabin pressurization, and that led to pilot incapacitation from hypoxia, because for unknown reasons, they were not able to access the emergency supplemental oxygen, which is required to be on board and operating properly, for all turbojet aircraft.  

There is another rather cryptic statement, in the Payne Stewart Learjet accident report:

Even though oxygen use was required on this flight (and perhaps others) and was reported to have been used, the Board is aware that pilots do not always use oxygen when required by regulation.

That is an understatement, in my view.  

My experience during my career at United Airlines, is that pilots routinely ignored the requirements of this FAR:

Sec. 121.333 - Supplemental oxygen for emergency descent and for first aid; turbine engine powered airplanes with pressurized cabins.

(3) Notwithstanding paragraph (c)(2) of this section, if for any reason at any time it is necessary for one pilot to leave his station at the controls of the airplane when operating at flight altitudes above flight level 250, the remaining pilot at the controls shall put on and use his oxygen mask until the other pilot has returned to his duty station. [1]

I always insisted that the pilots in my cockpit comply with that regulation.  The result was that I was considered to be somewhat of an oddball, since most captains did not require their crews to comply.  The willful violation of that particular FAR was widespread.  When I was a First Officer, I would put on the oxygen mask when the captain needed to leave the cockpit.  In most cases, the captain would tell me that was not necessary, but I would politely tell him that I preferred to put it on.

When the cabin suddenly decompresses at flight altitudes above 35,000 ft., the period of useful consciousness without supplemental oxygen, can be measured in seconds.  That is why both pilots have to have "quick don" oxygen masks at the ready, which will enable them to put them on and begin breathing pure oxygen, in a matter of seconds, should such an emergency occur.  It is also why one pilot must don and use the mask, whenever the other pilot finds it necessary to leave his seat, if the plane is flying above FL 250 (25,000 ft. above sea level).

If the plane does suddenly experience a sudden loss of cabin pressurization, the immediate required response of the pilots is to:

  • Don the oxygen masks; ensure the switch is in the 100% position

  • Retard the thrust levers to idle

  • Disengage the autopilot on some planes, or leave it engaged on others (depends on the cockpit design of that particular plane.  "Glass" cockpit planes usually leave the autopilot engaged).  If the autopilot is to be engaged, then the lower desired altitude must be set in the FG panel.  That means the plane can descend by itself on the autopilot, and then level out at a safer altitude, even if the pilots should somehow be incapacitated after initiating that rapid descent.

  • Extend the spoilers (panels on top of the wing, which act as speed brakes, when they are fully deployed).

  • Descend at maximum operating speed (this is popularly referred to as a "high dive" maneuver).

  • Transponder code to (xxxxx --- in this day of terrorism, I cannot reveal any of the required codes, for any of the variety of circumstances of a flight).

  • Ensure both oxygen mic switches are in the "on" position, so the pilots can communicate with ATC and with each other. [2]

  • Announce to cabin attendants and passengers, when time permits, that they should don their own oxygen masks.

  • Level the plane off at 10,000 ft., or higher if required by area terrain.

If that emergency procedure is followed, then a plane can lose its cabin  pressurization and still land safely.  

As I write this, more reports are coming in on the Helios Air crash in Greece.  The F-16 military pilots said they could see the First Officer slumped over in his cockpit seat.  No mention if they could see if he was wearing his oxygen mask.  They could not see the captain in the cockpit at all.  They could see the oxygen masks in use by the passengers in the cabin and some bodies were still wearing oxygen masks, during the rescue/recovery operations in the wreckage area.  Additionally, "a man whose cousin was a passenger on the plane told Greece's Alpha television he received a cell-phone text message minutes before the crash. 'He told me the pilots were unconscious. ... He said: Farewell, cousin, here we're frozen,' Sotiris Voutas said." [3]

It is getting to look more and more like cabin depressurization was a factor in this crash, yet it is still too early to say what might have caused such a depressurization or, if that did happen, why the pilots were not able to don their masks, get adequate oxygen for themselves, and then carryout the emergency descent procedure.  

Regardless of what conclusions will eventually flow from the accident investigation, it is my hope that all pilots around the world will take a look at their own attitudes about supplemental oxygen requirements and procedures:  

  • Are you one of those who scoffs at the "one pilot must don the mask, when the other leaves the cockpit" requirement?

  • Do you always conduct a thorough preflight of your pilot's supplemental oxygen system, including a check that the mask mic works properly?

  • Do you take the attitude that it could never happen to you, since sudden cabin depressurizations are indeed a very rare occurrence?

Those who have been thinking in that kind of maverick mode, need to seriously consider these two accidents, and realize there is a terrible price to be paid, for the failure to religiously adhere to all the supplemental oxygen regulations.


Nothing in this editorial is intended to imply the flight crew of the Helios 737 were negligent in any way.  It is way too early to apportion blame to anyone involved.  There may be other important factors, not revealed by initial news reports.  While it does appear likely that a cabin decompression did occur, we have a long way to go before it can be known what was the cause of that decompression and why the pilots were not able to respond in the proper manner, to prevent the final disaster.

That is what they will be trying to discover, as the official accident investigation progresses.  


[1]  Curiously, John Nance (ABC's resident expert on aviation accidents), said in an online chat interview, following the Payne Stewart crash: 

"In a commercial airliner, FAA rules require one pilot of the two to actually be using oxygen if his or her partner is out of the seat above 35,000 feet."  [emphasis by Editor, ASC]

I don't know if that was just a typo, or if John Nance was deficient in his knowledge about the FARs, relating to supplemental oxygen use by turbojet pilots.  The regulation actually says the mask must be donned by the remaining pilot, if the plane is above 25,000 feet.

[2]  Incredibly, John Nance also made this statement, in that same interview:  

"Whatever happened, it happened very rapidly because there was no time for the crew to request an emergency descent, which would be the first and most important action for a pilot after putting on your oxygen mask."  

I must strongly disagree.  When a plane is in a dire emergency situation, the first and most important decision of the pilot is always to immediately initiate whatever action is necessary, to save the plane and all on board.  When time is of the essence, the pilot informs ATC of what he is doing, as soon as that is reasonably possible, after the pilot has already taken that action on his own initiative.  No competent pilot waits until he can gain permission from ATC, before he takes necessary immediate actions to save the plane.  If you have to make an emergency descent, you do it first and then tell ATC later.  You do not seek anyone's permission first!

That may seem to be nit-picking to some, but when the plane is in a state of dire emergency, mere seconds can make the difference between survival and death for all.  

On July 11, 1991, a Nationair DC-8-61, operating as a religious pilgrimage charter flight from Jeddah, Saudi Arabia, to Sokoto, Nigeria, crashed as it attempted to return to Jeddah. Under-inflated tires, combined with a long taxi on a hot day, caused a fire in the main wheel-well right after takeoff.  The captain delayed his return to the airport, after being notified of smoke in the cabin.  The reason?  He was trying to get approval of the local tower controller to turn and descend, to make an emergency landing, while the fire raged out of control.  One report indicates he actually climbed to a higher altitude, when he misinterpreted an ATC instruction to another aircraft, as being a direction to his flight.  

On short final approach, the fire finally destroyed all control capability.  The plane suddenly pitched down and the lives of all 261 onboard were extinguished.

Had that captain turned and descended immediately, once he became aware of the emergency situation, he would likely have landed before control was lost.  It is probable that most, if not all of the lives of those 261 onboard, would have been spared. 

John Nance, is wrong.  A captain with a dire emergency, should not waste precious time seeking permission of ATC to take necessary emergency action.  He should immediately take whatever action is required, and then notify ATC as soon as he can, without compromising his attention being focused on saving the plane.

[3] It was just announced on radio news (1200 PST, August 15, 2005) that this was a hoax and that Sotiris Voutas has been arrested.  He did not have a relative on that flight at all.

See also: What the Media Should Know about Accident Reporting:

Robert J. Robert J. Boser    

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The Editor of this Web Page, now retired, was an airline pilot for 33 years and holds 6 specific Captain's type-ratings on Boeing Jet Airliners.


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