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Quoting Planesailing (Thread starter): (I believe yesterday was the first). |
Quoting Planesailing (Thread starter): bearing in mind the number of commercial aircraft that have sucessfully survived a controlled landing on water (I believe yesterday was the first). |
Quoting N14AZ (Reply 2): No, it was not the first succesful ditching: http://en.wikipedia.org/wiki/Ditching |
Quoting Planesailing (Thread starter): Is this switch well known of and included in a pilots training (is it on an emergency check list for example)? |
Quoting Planesailing (Thread starter): What has made Airbus include this and Boeing not? |
Quoting PhilSquares (Reply 4): It is in the Dual Engine Failure (ditching) checklist in the QRH. I am somewhat confused on why you would even infer the switch and it's function would not be part of the training? |
Quoting PhilSquares (Reply 4): Again, why do you think Boeing or only Airbus has this? In fact, every aircraft I have ever flown has either a ditching switch or a procedure in the QRH that would accomplish the same thing. |
Quoting Planesailing (Reply 5): Probably as I am not a pilot. Therefore, to learn, I have asked the question. |
Quoting Planesailing (Reply 5): Probably as I am not a pilot. Therefore, to learn, I have asked the question. I referred to it only being on Airbus aircraft as in the news article which I posted in the initial post it stated that only Airbus had this. |
Quoting PhilSquares (Reply 7): First of all, the Newsday is about the same as the Sun. I would also be cautious about taking anything technical as the truth when it comes from a news paper. To be honest, I pretty much ignore any news article regarding aviation, especially a subject like this, unless it comes from a technical publication. |
Quoting PhilSquares (Reply 7): In a nutshell, the Newsday piece is wrong. |
Quoting DTW757 (Reply 9): I also just heard on the media that the "ditching switch" is an advantage of the A320. Apparently Boeing doesn't have this? |
Quoting Planesailing (Reply 8): Looking at your profile you list yourself as a captain. In that case, could you enlighten us a little further regarding this ditching situation? |
Quoting Planesailing (Reply 8): Does Boeing also have this said suggested button, or is it a procedure that the captain must go through to get to the same end result of preparing the aircraft? |
Quoting Buckfifty (Reply 10): Not sure about the A320, but in the 330/340, we have a ditching pushbutton that closes all the holes in the fuselage (outflow valves, vent extract, ram inlet, PFCV and the cargo isol valves). Basically, anything below the waterline of the aircraft will be sealed to keep the water out. We use this switch all the time when we're deicing, to keep the deicing fumes from entering the aircraft. |
Quoting PhilSquares (Reply 11): On the 320, pressing the ditching button (located on the overhead panel) closes the outflow valve, the emergency ram air inlet, avionics ventilation inlet and extract valves and the pack control flow valves. (FCOM Vol 1.21.20 Page 7) Basically, it seals all the valves which are below the waterline so the aircraft will have some integrity. Every aircraft I have flown has a "ditch" switch. I can't remember about the 727 though. |
Quoting Planesailing (Reply 12): Whereabouts is it located? |
Quoting PhilSquares (Reply 13): It's located on the third row from the most fwd position, just to the right of center. It is on the anti-ice, window heat, cabin press area. It's the switch labeled "DITCHING" |
Quoting Planesailing (Thread starter): Is this switch well known of and included in a pilots training (is it on an emergency check list for example)? |
Quoting Planesailing (Thread starter): What has made Airbus include this and Boeing not? |
Quoting Planesailing (Thread starter): Is it included in all Airbus aircraft of just the A320 series? |
Quoting EstorilM (Reply 17): first of all, would all of these items be actuated in the event of a total electrical loss (as is presumably what happened yesterday..?) |
Quoting EstorilM (Reply 17): RAT was gravity-deployed AND automatic |
Quoting EstorilM (Reply 17): on what door that button closes |
Quoting Zeke (Reply 16): The only "Boeing" aircraft I know of with a "Ditching" switch would be the McDonnell Douglas aircraft like the MD-11. In all the Boeing procedure I have seen are like this for the 777, but no "Ditching" switch. "PACK SWITCHES (Both) . . . . . . . . . . . . . . . . . . . . . . . . .OFF [Ensures airplane is depressurized for opening passenger entry doors.] OUTFLOW VALVE SWITCHES (Both) . . . . . . . . . . . . . MAN OUTFLOW VALVE MANUAL SWITCHES (Both) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CLOSE Position outflow valves fully closed." They do not have a single switch that closes everything below the water line, the ditching switch on the Airbus closes not only the outflow valve(s), it closes the emergency ram air inlet, avionics ventilation overboard valve, cargo compartment isolation valves, pack flow control valves and the cabin fans stop. |
Quoting EstorilM (Reply 17): Wow so this raises another set of questions - first of all, would all of these items be actuated in the event of a total electrical loss (as is presumably what happened yesterday..?) Second, I thought the RAT was gravity-deployed AND automatic? Can you elaborate on what door that button closes, and what the checklist would be in this situation? Obviously maintaining control of the AC is your highest priority, however the drag (in the air/on water) from the RAT is undesirable. |
Quoting EstorilM (Reply 17): Second, I thought the RAT was gravity-deployed AND automatic? Can you elaborate on what door that button closes, and what the checklist would be in this situation? Obviously maintaining control of the AC is your highest priority, however the drag (in the air/on water) from the RAT is undesirable |
Quoting A10WARTHOG (Reply 20): |
Quoting Planesailing (Reply 19): The Airbus runs on fly by wire and a total engine failure would mean a lack of electrical supply. I always understood in this situation that the RAT deployed. Is there another way of obtaining the electricity, such as using the APU for example? Many thanks for all your input. |
Quoting Zeke (Reply 18): It would have been automatic with the loss of AC bus 1 and AC bus 2, I think it also has some form of assistance to deploy, the RAT is on the port side wing body faring. |
Quoting Planesailing (Reply 19): Would I be correct in saying in this incidence the Airbus offers the better system? |
Quoting Planesailing (Reply 19): Does the Airbus system make the aircraft more watertight? |
Quoting Planesailing (Reply 19): When we say the water line, where precisely does this mean up to? Would it be along the base of the windows? |
Quoting Planesailing (Reply 19): The Airbus runs on fly by wire and a total engine failure would mean a lack of electrical supply. |
Quoting Planesailing (Reply 19): Is there another way of obtaining the electricity, such as using the APU for example? |
Quoting EstorilM (Reply 21): I seriously doubt the thought of getting the APU started even entered their heads. |
Quoting EstorilM (Reply 21): I understand that the AC has batteries, however I thought these were low current (not to mention DC) for a few select items. |
Quoting EstorilM (Reply 21): For example, if the RAT failed to deploy and both engines had ceased to windmill (or at least to a low enough RPM, failing to provide hydraulic pressure) the plane would basically be impossible to fly, right? |
Quoting Zeke (Reply 18): The button does not close the RAT, it closes the emergency ram air inlet. That is a scoop that is used to force "ram" air into the cabin for emergencies like smoke removal, or if both air conditioning packs fail. it is very much like the air vents you have on cars that will provide external air into your car with the windows close and air conditioning off. |
Quoting Phatty3374 (Reply 23): |
Quoting Zeke (Reply 22): The APU has the same generator the engine has, it generates enough power to power the entire aircraft, which is very common on the ground before engine start. |
Quoting Zeke (Reply 22): See above, an inverter is in the circuit to convert it into A/C, they should last the best past of 30 min from memory. |
Quoting A10WARTHOG (Reply 25): I do not know about the A320, but on the 777 if you lose power the APU auto starts and the rat deploys. |
Quoting EstorilM (Reply 24): I swear I came across a document yesterday which showed the actual power outputs of the main engines, apu, rat, and batteries.. and the APU was significantly lower than the main engine generators. |
Quoting Phatty3374 (Reply 23): the RAT deploys and supplies the actuators with enough power to move basic control surfaces ailerons, elevators, etc.; |
Quoting Phatty3374 (Reply 23): for a water landing the RAT and ram air inlet are not deployed because the "ditch" button has been pressed and batteries provide actuators with enough electricity(?) |
Quoting Phatty3374 (Reply 23): APU is on (probably not enough time to start it up in a situation like yesterday, also would require lots of electricity?) |
Quoting EstorilM (Reply 24): the APU was significantly lower than the main engine generators. |
Quoting EstorilM (Reply 24): There wouldn't be enough current to energize any control surfaces or anything though. |
Quoting EstorilM (Reply 26): Just kidding, I stand corrected - both the main generators and APU are rated at 90kVA max, with the RAT rated at 5kVA. |
Quoting EstorilM (Reply 26): How would that work, with all the selector switches and everything? It automatically opens fuel supplies, alters power/air distribution, etc etc? I mean it would make sense, but I'm just wondering how many selectors that process would have to override. |
Quoting Zeke (Reply 28): The control surfaces move by hydraulics, not electricity. |
Quoting PhilSquares (Reply 4): Quoting Planesailing (Thread starter): What has made Airbus include this and Boeing not? Again, why do you think Boeing or only Airbus has this? In fact, every aircraft I have ever flown has either a ditching switch or a procedure in the QRH that would accomplish the same thing. |
Quoting Buckfifty (Reply 10): Not sure about the A320, but in the 330/340, we have a ditching pushbutton that closes all the holes in the fuselage (outflow valves, vent extract, ram inlet, PFCV and the cargo isol valves). Basically, anything below the waterline of the aircraft will be sealed to keep the water out. |
Quoting PhilSquares (Reply 11): As previously mentioned, Boeings have a similar switch that does the same thing. The procedure would normally be accomplished by the PM. |
Quoting Planesailing (Reply 19): Would I be correct in saying in this incidence the Airbus offers the better system? Presumably when a pilot is in such an emergency situation, the use of one switch over having to run through and check three is much better. |
Quoting Zeke (Reply 22): Quoting Planesailing (Reply 19): Would I be correct in saying in this incidence the Airbus offers the better system? Cannot say better or worse, just different. |
Quoting Zeke (Reply 22): Quoting EstorilM (Reply 21): For example, if the RAT failed to deploy and both engines had ceased to windmill (or at least to a low enough RPM, failing to provide hydraulic pressure) the plane would basically be impossible to fly, right? Still have mechanical backup on the rudder and stab trim, I have landed the 320 in the sim just using that (with engine power). |
Quoting EstorilM (Reply 30): This is slightly unrelated, but do you know how the braking system works on the Airbus AC as far as backups are concerned? For example, I guess you've only got the residual pressure to operate the hydraulic brakes below 150kts? I heard/read something about Airbus experimenting with electronic brakes, but this might have been on the A380 or A350/future designs. |
Quoting PGNCS (Reply 32): Certainly this switch exists on the A-320 series aircraft. Certainly all airliners have a ditching procedure, but I have never seen a Boeing with a ditching switch. None of the 727, 737, 757, 767, or 744's I have flown have this switch or an analogous one. Please enlighten us. |
Quoting Planesailing (Thread starter): Is it included in all Airbus aircraft of just the A320 series? |
Quoting CosmicCruiser (Reply 37): Here's what it does on the MD-11: not just airbus |
Quoting Zeke (Reply 16): The only "Boeing" aircraft I know of with a "Ditching" switch would be the McDonnell Douglas aircraft like the MD-11. |
Quoting Planesailing (Reply 19): Would I be correct in saying in this incidence the Airbus offers the better system? Presumably when a pilot is in such an emergency situation, the use of one switch over having to run through and check three is much better. Does the Airbus system make the aircraft more watertight? |
Quoting PGNCS (Reply 32): Zeke is tactful; in this case I am not: yes, the Airbus offers a superior system in this regard. |
Quoting EstorilM (Reply 24): Quoting Zeke (Reply 22): See above, an inverter is in the circuit to convert it into A/C, they should last the best past of 30 min from memory. This would be for instrumentation, emergency lighting/deployment features, etc? There wouldn't be enough current to energize any control surfaces or anything though. |
Quoting EstorilM (Reply 26): Quoting A10WARTHOG (Reply 25): I do not know about the A320, but on the 777 if you lose power the APU auto starts and the rat deploys. How would that work, with all the selector switches and everything? It automatically opens fuel supplies, alters power/air distribution, etc etc? I mean it would make sense, but I'm just wondering how many selectors that process would have to override. |
Quoting Tdscanuck (Reply 39): Although the Airbus system is certainly simpler to use in the very very rare situation that you need it, it also adds some complexity and wiring which increases your maintenance burden. Given that the net effect of Boeing's QRH procedure is the same as Airbus's ditching switch, I don't think it's obvious how that trade actually works out. Trade studies get ugly when one of the probabilities is really really low. |
Quoting Rwessel (Reply 40): It's been pointed out that this is also a useful function when being deiced, to ensure that the airplane is well buttoned up to prevent you from pumping vapors from the deicing fluid through the cabin and making people sick (as has happened several times in the recent past). It might with other fumes as well - like when someone spools up the 727 with water injection just ahead of you... So that seems like a handy function in far more cases than actual ditchings (and perhaps the control is misnamed). |
Quoting Rwessel (Reply 40): It's been pointed out that this is also a useful function when being deiced, to ensure that the airplane is well buttoned up to prevent you from pumping vapors from the deicing fluid through the cabin and making people sick (as has happened several times in the recent past). It might with other fumes as well - like when someone spools up the 727 with water injection just ahead of you... |
Quoting Tdscanuck (Reply 39): Although the Airbus system is certainly simpler to use in the very very rare situation that you need it, it also adds some complexity and wiring which increases your maintenance burden. Given that the net effect of Boeing's QRH procedure is the same as Airbus's ditching switch, I don't think it's obvious how that trade actually works out. |
Quoting Tdscanuck (Reply 39): Yes. It's fairly simple on the 777 because almost all the selectors are just feeding input bits to the computer system, so overriding them is just a matter of software code |
Quoting Tdscanuck (Reply 42): This certainly sounds like a function that is more likely to buy it's way on the aircraft. It might be a "free" benefit that the engineers could get onboard by calling it a ditching button when "deicing cabin comfort" wouldn't cut it. |
Quoting Zeke (Reply 43): Arr yes, the ditching button "function that is more likely to buy it's way on the" A320, but was a deliberate design consideration on the MD-11. |
Quoting Pihero (Reply 44): Apart from some gems, I haven't seen any post about the fact that the trailing edge flaps were deployed, suggesting that the crew had at their disposal either /or both green and yellow systems and that control of the airplane wasn't such a problem. |
Quoting Zeke (Reply 43): Arr yes, the ditching button "function that is more likely to buy it's way on the" A320, but was a deliberate design consideration on the MD-11. |
Quoting Pihero (Reply 44): Quoting Tdscanuck (Reply 39): Yes. It's fairly simple on the 777 because almost all the selectors are just feeding input bits to the computer system, so overriding them is just a matter of software code And of course, the B system doesn't add any "maintenance burden", right ? |
Quoting Pihero (Reply 44): Apart from some gems, I haven't seen any post about the fact that the trailing edge flaps were deployed, suggesting that the crew had at their disposal either /or both green and yellow systems and that control of the airplane wasn't such a problem. |
Quoting BuckFifty (Reply 45): the crew would not have shut them down for obvious reasons, and assuming that the engines haven't completely seized, they would have supplied enough hydraulic pressure to power the flaps. |
Quoting Tdscanuck (Reply 46): I don't know Airbus architecture as well as Boeing, but I don't believe the A320 uses a completely centralized function computer equivalent to AIMS. |
Quoting Tdscanuck (Reply 46): but where was it said that control of the airplane was a problem? |
Quoting Tdscanuck (Reply 46): They should have had windmilling engines, RAT, and/or accumulator. |
Quoting BuckFifty (Reply 45): But the crew would not have shut them down for obvious reasons, and assuming that the engines haven't completely seized, they would have supplied enough hydraulic pressure to power the flaps. |
Quoting Tdscanuck (Reply 46): Did the MD-11 use it for the same function (sealing during deicing) that the Airbus pilots say is the, by far, more common use of the ditching button? |