AA 737 Pressurization

[repariit]

An AA 737 at FL280 lost pressurization causing several pax and cabin crew to faint. The crew deployed oxygen. AC diverted and landed. I wonder what the cabin altitude was?

[Alber Ratman]

FL 280 then?:E

Outflow valve problem? rapid decompression? ANYBODY KNOW?

I'm all ears!;)

On a professional technical interest mind, not for reconsumpion..:hmm:

Thread starter has an American sense of humour.. I can tell!:E

Watch out for the Cyber Men.. "DELETE, DELETE!":p

[misd-agin]

Any official reports to back up "several pax and crew fainting"?

Report mentions the flight "lost partial cabin pressure", which is rather undefined right now.


AMR Flight Is Diverted to Ohio After Six Sickened by Partial Pressure Loss - Bloomberg (http://www.bloomberg.com/news/2011-04-01/american-airlines-says-partial-pressure-loss-sickens-six-people-on-flight.html?cmpid=msnmoney)

An American Airlines (http://www.aa.com/) jet lost partial cabin pressure in flight, sickening six people on board, and made an emergency landing in Ohio.
Flight 547 had climbed to 28,000 feet from Washington (http://topics.bloomberg.com/washington/)’s Reagan National airport en route to Chicago (http://topics.bloomberg.com/chicago/) when two attendants reported feeling dizzy, Tim Smith (http://topics.bloomberg.com/tim-smith/), an American spokesman, said today. The captain deployed oxygen masks as a precaution as four passengers also reported feeling ill or faint, Smith said.
“We believe this is a cabin pressurization issue, which can have multiple causes,” Smith said in an interview. Three passengers and one attendant on the twin-engine Boeing Co. 737-800 jet went to a hospital to be checked out, Smith said.
Pilots are trained to respond to any unexpected change in onboard pressure by descending as quickly as possible to about 10,000 feet, said Bill Waldock, a professor of safety science at Embry-Riddle Aeronautical University in Prescott, Arizona (http://topics.bloomberg.com/arizona/). Supplemental oxygen isn’t required at that altitude.
Flight 547 landed without incident at Dayton, Ohio (http://topics.bloomberg.com/ohio/), at 8:20 a.m., about an hour and 10 minutes after takeoff, Smith said. It carried 126 passengers and six crew, he said.
The plane’s Washington departure was delayed by about 30 minutes after mechanics for Fort Worth (http://topics.bloomberg.com/fort-worth/), Texas-based American conducted an unspecified inspection, Smith said. He couldn’t confirm whether the pressurization system was involved.
Gradual Leaks

Partial depressurizations happen “once or twice a month” on commercial airliners as leaks develop gradually around seals or in the pressurization system, Waldock said. The pressure loss may be so minor that it doesn’t require a diversion and emergency landing, he said.
“If it happens slowly, it feels kind of euphoric, like you’ve had a couple drinks” of alcohol, he said. “Most people recover pretty fast. Oxygen from the cabin masks is going to help a lot. It feeds in oxygen that’s mixed with outside air and it’ll help people breathe easier.”
An American MD-80 flown to Dayton picked up the passengers and departed for Chicago O’Hare at 12:57 p.m. local time. Mechanics flew on the plane to Dayton to check out the affected 737-800.

[Alber Ratman]

Forget the oxygen / air mix.. Mask supply is 100% O2, either from a cylinder or from a generator..:E

[aterpster]

Did they do away with cabin warning horns?

[heavy.airbourne]

aterpster: Not all airlines use cabin warning horns, installed or not

Alber Ratman: for passengers, the oxygen is mixed with cabin air in the oxy mask (steady flow w/bottles, (quickly) decreasing flow w/generators), don't use with smoke in the cabin.
Flight deck masks are set do 100%, initially, but should and can be set to mix with ambient air (steady pressure), to save oxygen, e.g. for prolongued crossing of high terrain.

[captjns]

Incident: American B738 near Dayton on Apr 1st 2011, medical emergencies (http://avherald.com/h?article=43a42f9d&opt=0)


Reading the report it appears there may have been a slow leak and not a R/D... almost indicative of no air to the packs.

Below is for supposition purposes only and nothing else.

Are "No Bleeds Takeoff" accomplished from DCA for performance enhancement?

If so, is it possible the APU was inadvertently switched off while performing the after start flows.

Despite briefing the "No Bleed Takeoff" procedure, I've seen eager F/Os still reach for the APU, switch (merely out of habit) many a time and hd to reminding them not 'UH UH UH... don't touch the switch.

DCA departures can be rather busy for crews with close attention being required after takeoff to avoid restricted airspace thus leading to distractions relating to attention to the jet itself.

It has happened in the past and it will happen again as reconfiguring the engine bleeds and isolation valve switch on the A/C Panel.

[aterpster]

heavy.airborne:
aterpster: Not all airlines use cabin warning horns, installed or not
It's been a long time, but I seem to recall on the 767 it was a high-alert EICAS message with an audible alert.

Here are the certification requirements:

FAR 25.841(b)

(5) Instruments at the pilot or flight engineer station to show the pressure differential, the cabin pressure altitude, and the rate of change of the cabin pressure altitude.

(6) Warning indication at the pilot or flight engineer station to indicate when the safe or preset pressure differential and cabin pressure altitude limits are exceeded. Appropriate warning markings on the cabin pressure differential indicator meet the warning requirement for pressure differential limits and an aural or visual signal (in addition to cabin altitude indicating means) meets the warning requirement for cabin pressure altitude limits if it warns the flight crew when the cabin pressure altitude exceeds 10,000 feet.

[heavy.airbourne]

:ooh: aterpster: Just misunderstood, no warning horn in the cabin, but an aural warning on flightdeck with cabin alt greater than 14.000' (or similar).

[captjns]

Negative heavy.airbourne... Takeoff Configuration / Cabin Altitude Warning Horn in the cockpit sounds at cabin pressure of 10,000.

O2 Masks in the back drop at 14,000 cabin pressure altitude.

[heavy.airbourne]

Seems to be different on many a type. Last flight on B732 in '89, looks like I'm out of the loop. :(

[Denti]

NGs nowadays have an additional cabin altitude warning light above the PFD and another one for take off config warning since it is the same horn. Anyway, primary field of view and a bright red light should help in discovering something's wrong.