Ryanair B738 near Zurich on Feb 6th 2012, loss of cabin pressure
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Certain I briefly saw the thread yesterday after it was moved. Had been attached to another Ryanair one. Cant remember the title, or under what forum (something to do with specific airlines/bases?), just that it was up to about 2000 comments. Not sure what was going on there
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And what about the "alleged" incident in BCN where an AA aircraft had its stab touched by a RYR winglet at the holding point, Capt was "allegedly"notified via an Engineer sitting at the overwing who alerted the CC, but nonetheless said nothing to the Tower ,or the AA aircraft, flew 2 sectors & then p1ssed off home without writing anything in the tech-log, but having had a quick look at the wing before leaving ( as this is 3rd hand, I will add again "allegedly" )
"Allegedly" the AA had a fair bit of damage on arrival, having traversed the Atlantic.
If true, strange how the person concerned, with (allegedly) one previous off runway misdemeanour to her name, has suffered only a seat change. (must give REALLY good head
)
"Allegedly" the AA had a fair bit of damage on arrival, having traversed the Atlantic.
If true, strange how the person concerned, with (allegedly) one previous off runway misdemeanour to her name, has suffered only a seat change. (must give REALLY good head
)
Last edited by captplaystation; 7th Feb 2012 at 13:24.
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Just spoke to my cousin who was a pax on the this flight. It ws en route stansted. She said the masks dropped when over the Alps and the Flt Crew over the PA said " mayday emergency landing"! She was petrified and assumed a crash landing in the mountains.
She smelt burning but thinking back, the 73 has chemical oxy generators for pax ox. They did an emergency descent and diverted to FRA. She was extremely relieved to hear they weren't crash landing! Shame about the misleading announcement.
The Ox masks can be a bit of a pain (flight crew), poss inadvertent transmission on the PA. Defo not a time that I'd be considering talking to the pax!
Al'ls well that ends well and she's not too worried about her return flt on wed now.
She smelt burning but thinking back, the 73 has chemical oxy generators for pax ox. They did an emergency descent and diverted to FRA. She was extremely relieved to hear they weren't crash landing! Shame about the misleading announcement.
The Ox masks can be a bit of a pain (flight crew), poss inadvertent transmission on the PA. Defo not a time that I'd be considering talking to the pax!
Al'ls well that ends well and she's not too worried about her return flt on wed now.
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Hmm, not convinced this is the same Ryan flight. I though hers was more recently but failed to ask. It was Bergamo Standsted so very likely the same flight with some eroors in previous reports. She also said the newspaper write ups, no surprise here, were total crap.
With almost 5000'/min rate it takes a little more than 4 minutes to get down from F360 to 14000'; it's not such a long time to... "Aviate, navigate, communicate" & "Dive and drive"!!!
<<When you call 'MAYDAY', if you can get some sort of ATC clearance before you plummet, so much the better. It would be pointless doing the drill perfectly and then slamming into another aircraft beneath you on the way down. The TCAS telling you 'CLIMB . . . CLIMB' won’t be much use at this point. The question is: 'how long do I spend trying to get an emergency descent clearance?' And of course no-one can give you an answer – you must use your judgement as to when to start down if ATC can’t help. However, remember you've got 12 minutes of passenger and cabin crew oxygen available and considerably more for the pilots. If you stay aloft a short time while you get a clearance and then descend at current IAS (in case of damage) you'll still have plenty of time to get down to breathable air before the oxygen runs out.
One of the difficulties in this scenario is communication with cabin crew – they can't talk to you with their masks on, so it's one way traffic only. Having done the QRH checklist you could do a combined PA for both the cabin crew and the pax, along the lines of: '. . . we've lost cabin pressure, so everyone make sure you've got your oxygen masks on . . . cabin crew stand by for further instructions . . .'. At the end of the descent your PA could be '. . . cabin manager, take off your mask and report to the flight deck . . .' Or if for some reason you need to talk to the cabin manager during the descent, you could tell him on the PA to don a portable bottle and report to the flight deck. He can then listen to what you say over the speaker.>>
The 12 minutes refers to the B757/767 but I would expect other aircraft to have similar oxygen endurance.
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The pressurisation system is it's weakness
Discorde: Above 30,000ft. cabin altitude the human body needs pressurised O2 to function correctly. This is supplied to the pilots through their equipment but is not afforded to the passengers who only have free-flow O2. Therefore I would suggest that extended periods at very high cabin altitudes (ie. 30,000+ ) is not a good idea. I am sure that certification requirements assume a response time scale.
Good point, Meikleour. It's a judgement call, or risk analysis if you like. There are competing demands - the need to restore normal breathing capability and the need to avoid other traffic during the descent. Additionally, a violent decompression might signify aircraft damage, which requires restricting IAS, and hence reducing descent rate.
Above 30,000 feet, if you descend at current IAS (with speedbrake deployed) you'll initially maintain a highish Mach No & descent rate. Both of these parameters will reduce as altitude reduces. But by then atmospheric oxygen partial pressure is increasing. This procedure will bring you down to breathable air reasonably quickly.
Above 30,000 feet, if you descend at current IAS (with speedbrake deployed) you'll initially maintain a highish Mach No & descent rate. Both of these parameters will reduce as altitude reduces. But by then atmospheric oxygen partial pressure is increasing. This procedure will bring you down to breathable air reasonably quickly.
Hi Discorde: I was not trying to open a debate about damage/no damage descent techniques I was merely trying to draw attention to an area that in my experience is scantily covered during training. Namely the risk to passenger health at excessive cabin altitudes. Once below 30,000ft. the risk is vastly reduced. I am sure that you will remember that a certain three- engined product from Hatfield did not even have a pax dropdown system fitted! Cue here to review response time!
This factor is more common now with so many aircraft operating at F390/F410 today.
This factor is more common now with so many aircraft operating at F390/F410 today.
De Havilland's tri-motor was always more enthusiastic about descending than climbing, particularly with reverse pulled on 1 & 3. So no need for drop-down oxygen!
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Emergency Descent Cabin Altitude Requirements
The FARs call out two basic requirements for maximum cabin altitude:
1. Never above 40K feet.
2. Time above 25K feet shall be less than 2 minutes.
The first one is usually met by assuming a "reasonable hole size" - about the size of a single cabin window. With airplane ceilings at about 43K feet, it does not take much of a descent to satisfy #1.
The second requirement above is the tricky one. The airplane must essentially be able to descend to 25K feet true altitude in two minutes or less. The proceedure is speedbrakes up, idle thrust, push over to accelerate to near Mmo. Transitioning from Mmo to Vmo is a bit of a challenge as it requires pulling the nose up several degrees. Descent along a line of constant Mach number involves accelerating in terms of true airspeed. Descent along a line of constant Vcas involves decelerating in terms of true airspeed. Fortunately the Vmo/Mmo corner altitude is not much above 25K feet for most models so once you are down to the point where you reach Vmo you are almost down to 25K.
Another consideration is that while emergency descent rate is slowest when heavily loaded, a heavy airplane will be cruising at a slightly lower altitude than a lighter one and thus does not have as far to go to get to 25K feet.
1. Never above 40K feet.
2. Time above 25K feet shall be less than 2 minutes.
The first one is usually met by assuming a "reasonable hole size" - about the size of a single cabin window. With airplane ceilings at about 43K feet, it does not take much of a descent to satisfy #1.
The second requirement above is the tricky one. The airplane must essentially be able to descend to 25K feet true altitude in two minutes or less. The proceedure is speedbrakes up, idle thrust, push over to accelerate to near Mmo. Transitioning from Mmo to Vmo is a bit of a challenge as it requires pulling the nose up several degrees. Descent along a line of constant Mach number involves accelerating in terms of true airspeed. Descent along a line of constant Vcas involves decelerating in terms of true airspeed. Fortunately the Vmo/Mmo corner altitude is not much above 25K feet for most models so once you are down to the point where you reach Vmo you are almost down to 25K.
Another consideration is that while emergency descent rate is slowest when heavily loaded, a heavy airplane will be cruising at a slightly lower altitude than a lighter one and thus does not have as far to go to get to 25K feet.
Thanks for your input FCeng84. The difficulty with the '25k within two minutes' requirement is the congested airspace in many regions of the world. In the worst case scenario rapid descent before or without ATC authorisation could lead to collision, which would clearly be more hazardous than hypoxia amongst some pax. TCAS in RA mode might give inappropriate commands and in TA mode might not give sufficient data to avoid conflict at very high descent rates. Unless there has been a change in policy, the 757/767 QRH also requires restricting airspeed if airframe damage is suspected (my highlighting).
Perhaps I'm reading these replies wrong, and call me picky, but why are so many people (Pennellino, PENKO, JW411 and even I-2021) talking about descending to FL100? It's 10000 feet people! PENKO perhaps it's your licence which needs looking at 
DOVES what are you on about with 14000'? That's the cabin altitude the masks automatically drop down if the altitude inside raises that high. It's not the altitude you descend to during an emergency decent.
DOVES what are you on about with 14000'? That's the cabin altitude the masks automatically drop down if the altitude inside raises that high. It's not the altitude you descend to during an emergency decent.
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Discorde,
Just a quick thanks for the link to "How to do well in the Sim", never seen that before & a quick glance suggests it is a thought provoking & well thought out piece, Cheers for that
Just a quick thanks for the link to "How to do well in the Sim", never seen that before & a quick glance suggests it is a thought provoking & well thought out piece, Cheers for that
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Interim Report : http://www.bfu-web.de/cln_030/nn_119...737_Lugano.pdf
Very good maintenance
Ryanair blablabla
Very good maintenance
Ryanair blablabla
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How expeditious does the descent need to be after loss of cabin pressure? There will be at least 10 minutes' worth of oxygen for pax and crew (and probably more for the pilots). A quote from 'How To Do Well In The Sim':
