Helios 733 crash north of Athens

[KevinAu 441]

>At the end of the day Kevin, I would suspect your theories>are pretty close. Still there remains some stinking facts:>>* System monitors did not appear to alert crew>* Absence of PIC (back of plane perhaps, trying for O2)>* Folks seen in cockpit>>The whole thing seems like an episode of the Twilight Zone.>>At the end of the day, I go back to my title for this>sub-thread:>>"Can't explain the unexplainable.">>Cheers,>>bt>As much as I would like this to be a twilight zone in real life or proving the existence of Grays, none of those three things are unexplainable.1. You do not know that the system monitors did not alert the crew. Like I said earlier, the pressurisation problems were a known and recurring gripe on that particular aircraft. When the cabin altitude caution sounded, the crew was faced with one of two choices. Continue the climb and continue troubleshooting the system. Or they could ask ATC for a stop at/descend to 10,000' to keep the cabin altitude breathable while they troubleshot the system. There is nothing to indicate that the cabin altitude warning did not sound. The issue here is a human factors one. Why the pilots chose to continue is something which the psychologists/human factors/CRM specialists on the investigation would look into. Factors such as personalities, past experiences with that aircraft, corporate culture, training, etc. are the issues here.2. The PIC could have been either removed from the seat by the F/As or could have collapsed while reaching for something, say....the crew oxygen bottle at the rear of the cockpit. The $64,000 question for the investigators will be why the cockpit crew emergency oxygen system failed. I've already outlined in a previous post the technical aspects of the said oxygen system that make it vulnerable to failures. The bottle could have been turned off accidentally, it could have been empty to begin with, there could have been a kink in the line, etc.3. As far as people in the cockpit, there is no mystery here either. In a previous post, I had already explained that there are several portable O2 bottles in the cabin for the use of F/As and medical purposes. It has already been reported that the blood found in the cockpit belonged to two flight attendants. Obviously, at least two of the flight's F/A's had enough wits to grab for the POBs. They would have provided almost two hours of O2 for them. Nothing twilight zone about that.As with most accidents, this one was also a chain of small events and decisions that led to a smoking hole. It began with an airline running on the cheap that operated a 737 that had a historically faulty pressurisation system which their maintenance never fully corrected or rectified. When the system failed again that particular day, the pilots decided to troubleshoot it "on the go" instead of making a big deal out of it and doing some of the things that their training department probably would have expected them to do. Once they decided to continue the climb, they may have ran into a second, latent, deficiency with that aircraft...that of the cockpit emergency O2 system. Once the hypoxia overcame the pilots, there was nothing left but for the plane to continue up to 34,000 and fly the flightplan route all the way to the missed approach holding fix by itself. At least two of the F/As were able to stay coherent through the entire episode by use of the POBs, and gained access to the cockpit. Unfortunately, those F/As answered the famous question of "If the pilots were incapacitated, could I take over and land the plane?" in the negative. Too bad none of you guys who fly the PMDG and DF 737s here on the Avsim forums were aboard...the outcome may have been very different.

[KevinAu 441]

That of course would be the best thing to do. Even if you were able to get into the cockpit and had the wits to make for the radio...what frequency would you use? What if you were already out of range of the facility that was already in the comm? Do you know where the PTT is and how to operate it? They're not always on the yoke and they are not always a push, you know. Would a passenger know how to find a usable frequency on the charts that are clipped by the pilot's side window? Most likely, the Jepps that the pilots had out were for the departure airport....maybe hundreds of miles behind by now. Would a pax know where to dig into the pilot's flightcase to find the Jepps and a page with a good frequency? Would a pax know what frequency Guard is? Did the Greek F-16s have VHF to even talk to that plane with? I would say that the chances of a nonpilot civilian that managed to get into that cockpit being able to successfully find help on the radio is less than even. The most likely way anybody could have gotten help on the radio is if some other airplane that happened to be on that frequency heard a cry for help. Another airplane would most likely have been the only other people to hear them, once they flew out of range of the ATC facility that the pilots were tuned into before they passed out.

[rickalty 0]

Reuters have reported that someone at least got into the cockpit and used the radios.....----QUOTE-----ATHENS (Reuters) - An exhausted-sounding man sent last-minute Mayday calls from a Cypriot airliner that crashed earlier this month, Greek officials investigating one of civil aviation's most baffling incidents said on Monday..........the crash's chief investigator said a steward who had some flight training was thought to have made the last gasp cry for help from the plane's cockpit...Police have confirmed steward Andreas Prodromou, who was learning to fly small planes, was inside the cockpit and appeared to be trying to fly the plane for about 30 minutes before it crashed."The man who sent the Mayday calls sounded tired and exhausted," the letter said.Greek media reported Athens control tower did not pick up the warnings because they were transmitted on a wrong frequency.----ENDQUOTE----Richard

[Tabs 2,790]

With regard to the cockpit altitude warning horn, the prevailing theory on the PPRuNe forum right now is that the crew mistook the cabin altitude alarm for an erroneous takeoff warning config horn, rather than this idea that they decided to continue the climb while troubleshooting a pressurization issue - that wouldn't make any sense at all, climbing higher would obviously exacerbate the problem. The plane never pressurized according to sources, so they would have recieved the warning shortly after takeoff, which is consistent with the possibility that they thought the horn was a different error. The 737-300 doesn't have EICAS in the same way that the later glass Boeings do where it gives you a specific message about the nature of the problem...

[Guest vas_yan]

The one thing that still has not been explained sufficiently, in respect of the theory of decompression and the CC using portable O2 tubes to survive until the end is, how did the passengers survive until the crash... According to the coroners everybody onboard was alive at the time of the crash (though perhaps unconscious?). AFAIK hypoxia entails brain damage after a few minutes and death after 15 minutes or so. The plane is said to have spent a couple of hours at the high FLs with the pressurisation problem being present from the beginning. Any views on this?Regards,

[Guest cybervet]

There is a possibility that there was a partial pressurization inside the cabin , lets say that the cabin pressure stack to fl180 or fl200 that would give a higher time margin to the passengers and to the flight crew and even though they would be unconsious they would still be alive for a couple of hours.Also it was presented to the greek media that just before the flight 3 helios mechanics were troublesouting the aircraft for pressurization probs and there is a possibility that they forgot the cabin pressure switch to full manual instead of auto.Tassos

[KevinAu 441]

Though there is no Eicas, the 737-300 does have an annunciator panel on the glareshield in front of the pilot's faces. One of the annunciations on that panel is labeled "Air Cond" and will illuminate with the master caution if there is a duct overheat, dual bleed condition, pack trip off, wing-body overheat, bleed trip-off, AUTO FAIL, off schedule descent, zone temp, and PACK. As you see, there are two conditions here that are relevant, autopressurisation failure and pack failure that would have caused it to illuminate.I think that we can all accept that the pressurisation failed on/during/shortly after takeoff. The question is why did the pilots continue climbing to 34000 despite this. The reasons are wide and varied and my speculation is certainly as good as anybody elses' speculation who knows the aircraft systems. Certainly, I could buy the theory that they were confused about what was actually happening and failed to recognize the pressurisation or pack failure for what it was and continued the climb. Of course, this would have to be rectified with the reports from the media that they had reported an air conditioning problem. So if they did actually make that report, then they had to have known there was a pressurisation problem occuring. So this scenario kind of has some problems jiving with the currently reported "facts".So there is one of two possibilities, that they did not recognize the pressurisation problem and continued, or that they recognized it, were resolving or thought they had resolved it, and continued.

[Guest advocatexxx]

recent update: "..it was determined that a body found in the cockpit area was that of a female flight attendant, suggesting that she was indeed trying to prevent a crash. A steward serving on the flight was also thought to be a fully qualified commercial pilot, and there are reports he disengaged the Autopilot of the plane and was trying to fly it to safety. Autopsies on 45 crash victims (including the co-pilot) show that all were alive and maintained cardiac and respiratory function upon impact, but it could not be determined whether they were conscious at the time."sounds to me like the captain wasn't anywhere near the cockpit. also, what the #### was the plane doing at FL340 on such a short flight?

[Guest advocatexxx]

more possibly useful info:"It seems that no discussion has been recorded in the second black box of the Helios Boeing, which crashed killing all 121 on board. According to sources, in the discussion recorder in the pilot

[KevinAu 441]

>>sounds to me like the captain wasn't anywhere near the>cockpit. also, what the #### was the plane doing at FL340 on>such a short flight?>>Fuel efficiency. The most efficient flightplan would have the aircraft fly a parabolic trajectory, spending only a few minutes in level cruise before beginning descent. I've been on SFO-LAX with a cruise altitude of FL410. We only spent a few seconds at FL410 before descending.

[Guest cybervet]

Ok latest news today about the helios , master caution warning sound was going on at the same time for at least 2 different reasons something that comfused the pilots (maybe they were troubleshooting a computer heating prob and lost valuable time?).Radios were functional since voices of other a/c were recorded but tuned to the wrong ATC frequency (that of Nicosia and not Athens).Tassos

[KevinAu 441]

http://www.iht.com/articles/2005/09/06/news/crash.phpLooks like it was simply two guys with poor systems knowledge who didn't speak the same language. Never realized they were not pressurising and passed out.

[michal 44]

Very interesting.Michael J.WinXP-Home SP2,AMD64 3500+,Abit AV8,Radeon X800Pro,36GB Raptor,1GB PC3200,Audigy 2http://www.precisionmanuals.com/images/forum/747400.jpghttp://www.hifisim.com/images/asv_beta_member.jpg

[btacon 1,772]

>http://www.iht.com/articles/2005/09/06/news/crash.php>>Looks like it was simply two guys with poor systems knowledge>who didn't speak the same language. Never realized they were>not pressurising and passed out.Hey Kevin...something like this probably happened, but your "simple facts" are not so sure of themselves..."The Greek authorities have made cryptic statements hinting at oxygen problems but have so far not announced the full findings of investigators. The people interviewed for this article agreed to do so on condition that they not be identified because none are official spokesmen for the investigation and because of political sensitivities arising from a Cypriot plane crashing in Greece."Cheers,bt

[btacon 1,772]

Kevin...where was the pilot?Cheers,bt