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Air China plane dropped more than 6,000m

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Air China plane dropped more than 6,000m

Old 12th Jul 2018, 09:59
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Air China plane dropped more than 6,000m

Chinese authorities are investigating why a plane was forced to drop more than 6,500m (21,000ft) due to loss of cabin pressure.

The Air China flight from Hong Kong to Dalian lost altitude rapidly and oxygen masks dropped in the cabin.

The plane then returned to cruising altitude and continued as scheduled.

There is speculation in local media that crew had been smoking in the cockpit and then mishandled the ventilation system.

Chinese aviation authorities are examining both the flight data recorder and the cockpit voice recorder to determine what caused the inciden
BBC - China investigates why plane dropped more than 6,000m
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Old 12th Jul 2018, 11:41
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The plane then returned to cruising altitude and continued as scheduled.
That doesn't sound right. Surely if the masks deploy and the O2 is used, if you climb back to high altitude again, what are the passengers to do if you have a repeat ? Or the crew for that matter?

Suspect reporting here.

"These planes fly at an altitude that at Mount Everest is called the death zone because of a lack of oxygen," aviation expert Greg Waldron of Flight Global told the BBC.

"So the pilot absolutely has to bring the plane lower. Otherwise, crew and passengers would get unconscious."

'The death zone'? Really, where do they find these 'experts'.
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Old 12th Jul 2018, 12:10
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Drop down masks only required above 25000 feet.
Maybe that was the new cruise altitude. Maybe it wasn’t.
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Old 12th Jul 2018, 12:52
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Yes. Drop down mask must be installed if aircraft certified to cruise above FL250!
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Old 12th Jul 2018, 12:56
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Originally Posted by favete linguis View Post
I think you'll find MP is taking the pi$$ - try a lower figure, between say 13 & 15,000 ft ;-)
no he isn't
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Old 12th Jul 2018, 13:05
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Correct because of the certification requirement to be able reach 14000’ within 4 minutes.
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Old 12th Jul 2018, 13:09
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How is a certification requirement more appropriate to turboprops relevent to this incident where a 737 descended 21,000' (we suppose from FL310)?

I presume the 73 airframe in question has chemical O2 generators rather than an oxygen main so when they climbed again how was the risk of a subsequent depressurisation mitigated? ...Or did they not think of that?
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Old 12th Jul 2018, 13:11
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It’s not but now you’re aware of it and you weren’t before. Every day is a school day.

Why are are you asking us what they were thinking?!

Oh and the certification requirement is more relevant to jets that may not be able to reach 14000 within 4 minutes. Think about it.
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Old 12th Jul 2018, 14:52
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Also covered by CNN: https://edition.cnn.com/2018/07/12/a...ntl/index.html

Citing unnamed industry sources, multiple Chinese state media outlets reported the cockpit crew were smoking in violation of aviation regulations, and caused the loss of cabin pressure and drop in altitude when they mistook two switches as air recycling fans and turned them off.
I'm much less concerned about the smoking in the cockpit and more concerned that they appeared to be pushing buttons randomly to find out what they do!

Last edited by akaSylvia; 12th Jul 2018 at 14:53. Reason: fixed quote
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Old 12th Jul 2018, 17:14
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From the FR24 data it looks like the B-738 initially climbed to 10700 meters (FL351). They then did the Rapid D high dive down to 3300 (or perhaps 3000) meters (FL108) and then climbed back up to 7500 meters (FL246) and then 8100 meters (FL266) before starting the descent into Dalian.




Pictures of the rubber jungle and 'air safety expert' analysis in this SCMP article:
https://www.scmp.com/news/hong-kong/...-25000-feet-10

It's been a while but I've sure seen pilots try some odd pack and recirc fan tricks to try to hide smoking in the cockpit on larger planes. However, these days if you try any non-standard systems configurations a fault message goes back to headquarters and you'll get a message to call flight ops when you land.

Originally Posted by akaSylvia View Post
I'm much less concerned about the smoking in the cockpit and more concerned that they appeared to be pushing buttons randomly to find out what they do!


These knobology failures are nothing new, for example:

American Trans Air had a decompression incident on the 727 in the 1990s where the cabin altitude warning horn went off on climbout and the captain noticed that one of the packs was off. He told the FE to do something about that pack. The FE complied and turned the other pack off as well. Captain and FE passed out yelling at each other, the FO got his mask on and saved the day.


In 1987 a Delta captain somehow confused square buttons with round knobs and shut off both engines on a 767 out of LAX. He got the motors started and they pressed on to CVG where salt spray was rinsed off the plane prior to the next leg to LGA. The square buttons were subsequently relocated far away from the round knobs to prevent a reoccurrence. The captain was relocated away from the Delta flight deck as well.
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Old 12th Jul 2018, 22:27
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I-FORD. That makes sense. Never had to do it, so don't know the facts. However, operating turboprops many years ago, with no pax oxygen, we were limited to FL 230 with pax, FL 250 without. On an unpressurised Turboprop, under UK regs, flight above FL 100 was limited to 20 min, and a maximum of FL 120.
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Old 13th Jul 2018, 00:14
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Possibly both packs turned off by mistake, cabin altitude alert warning followed by mask deployment and emergency descent. Error realised, packs turned back on, cabin pressurises and flight continues.

Non ETOPS so no 2 engine depressurised figures figures in the flight plan. A climb back to normal cruising altitude should only be considered if fuel critical, no diversion airport available and the cause of the pressurisation failure was a crew error not a system problem.

In some areas of China the terrain is so high that additional passenger oxygen has to be carried on certain routes as a descent to 10 000' may not be possible.

If a suitable airport was available a diversion would be the preferred option. Emergency descents often leave passengers requiring medical attention.
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Old 13th Jul 2018, 07:05
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Originally Posted by krismiler View Post

In some areas of China the terrain is so high that additional passenger oxygen has to be carried on certain routes as a descent to 10 000' may not be possible.

.
Folks,
In China, some airports are so high the crew has to wear supplemental oxygen on the ground during a turnaround.
Tootle pip!!
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Old 13th Jul 2018, 10:44
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Originally Posted by TURIN View Post
'The death zone'? Really, where do they find these 'experts'.
the Death Zone

That's exactly what mountaineers do call it.
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Old 13th Jul 2018, 10:57
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Originally Posted by LeadSled View Post
Folks,
In China, some airports are so high the crew has to wear supplemental oxygen on the ground during a turnaround.
Tootle pip!!
True, but there would be no such harrowing terrain to be found on a VHHH-ZYTL leg.

Having done a stretch as a vagrant jobseeker in the Middle Kingdom, I've often wondered aloud what it would take to make the locals stop smoking in the cockpit. I hadn't imagined quite so dramatic a scenario, but if the initial rumours of the cause are true, this just might do the trick.
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Old 13th Jul 2018, 11:16
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So it seems like alcohol addiction is not the only substance addiction creating flight safety issues. Yet the world (of aviation culture and of law) is rightly hard on drinking and flying, but smoking and flying gets a pass.

Apart from apparently causing a tendency to try to remove the air supply from the aircraft in flight, what if the e-cig catches fire or explodes? It's not going to do the flight crew or the cockpit any favours to have the e-cig explode in the user's face and blast fragments around the cockpit at high speed.

(Occasionally gory compilations of exploding e-cigs can be found on youtube, not linked here because the preview is quite grim)
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Old 13th Jul 2018, 15:04
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news.sina.com.cn/o/2018-07-12/doc-ihfefkqr2429480.shtml
news.sina.com.cn/c/2018-07-13/doc-ihfhfwmu9113462.shtml

From the sources above:
2018年7月10日,国航CA106航班执行香港至大连航班任务。在巡航阶段,飞机出现座舱高度警告,机组人工释放了旅客氧气 面罩,并实施紧急下降,于北京时间22:31分在大连机场安全落地,机上153名旅客, 9名机组成员,无人员受伤,飞机没有受损。
"July 10, 2018, flight AirChina CA106 was en route from Hong Kong to Dalian. During the cruise, there was a cabin altitude warning, and the crew has manually released the passenger oxygen masks and performed an emergency descent. The plane landed safely at Dalian airport at 22:31 Beijing Time, there were no injuries among all the 153 passengers and 9 crew members. The plane was also intact".

知情人士爆料,7月10日国航CA106航班机组在飞行途中抽烟,误把两个组件当成再循环风扇关掉导致座舱释压,飞机宣布May day紧急下降;机组在发现问题后,打开组件增压并在氧气不符合适航条件下又重新上升到7500米高度继续飞往目的地。
According to sources, the crew of CA106 on July 10th was smoking during flight, and mistakenly turned off two components that they thought were recirculation fans, which led to pressure-release from the cabin. The plane declared "Mayday" and performed an emergency descent. Once the crew has identified the problem, they turned the component back on, and ascended to 7500 meters to the destination under the oxygen condition that's not suitable for cruising.

“机舱温度升高,整个空调系统好像停了。”一位乘客王先生说。当时机舱内广播通知:“飞机可能失密,正在紧急下降,请保持安静, 系好安全带。”
"The temperature was raising in the cabin, and the entire A/C system seemed to be turned off" - A passenger Mr. Wang said. The cabin announcement: "it's possible that the plan has lost its seal, and we are performing an emergency descent, please stay calm and fasten your seatbelt."

Another source:
news.sina.com.cn/o/2018-07-13/doc-ihfhfwmu5229093.shtml
经过初步调查,系副驾驶因吸电子烟,为防止烟雾烟味弥漫到客舱,在未通知机长的情况下,实际上想关循环风扇,错误地关闭了相邻空 调组件,导致客舱氧气不足,客舱高度告警。
According to preliminary investigation, it's caused by the co-pilot smoking e-cigarette. To keep the smoke and smell away from the passenger cabin, the co-pilot, without informing the captain, with the intention of turning off the recirculation fan, but mistakenly turned off the A/C component located next to it, which led to insufficient oxygen in the cabin and cabin altitude warning.
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Old 13th Jul 2018, 15:31
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Also some aircraft have oxygen tanks in stead of chemical generators. If it is a tank, you can schut it off again and if there is enoughpressure left, you are good to go.
With all that high terrain there they probably have tanks and to cope with winter operation they probably are larger as well.
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Old 13th Jul 2018, 16:01
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Air China

All 73S after the 200 have oxygen generators for the pax and tank for the flightdeck
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Old 13th Jul 2018, 16:31
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Emergency descent caused by copilot vaping

According to the BBC, per the CAAC, the emergency descent was caused by the copilot vaping, then trying to prevent the smoke going into the passenger cabin by turning off a fan, but he accidentally turned off the AC instead, the 02 level then dropped, etc., etc.: https://www.bbc.com/news/world-asia-china-44818617

Unbelievable.
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