There's been much discussion about US Airways Flight 1549 and the extraordinary circumstances that befell the Airbus A320-200 (N106US) and her compliment of 150 passengers and 5 crew. At least preliminarily, it appears a double bird strike disabled each of the CFM56-5B4/P engine forcing Captain C.B. Sullenberger III and his First Officer to ditch the jetliner in the Hudson River.
As the aircraft was making its 'final approach' to the Hudson, the crew was preparing the aircraft and its passengers for the water landing, including, some speculate, by activating the ditching system on the A320. The button, cleverly labeled 'ditching', is located on the 'Cabin Press' section of the overhead panel shown above.
So what does that infrequently used button actually do?
When pressed, it commands the aircraft operating system to close the outflow valve, emergency ram air inlet, avionics inlet, extract valve and flow control valve. In addition, it will immediately shutdown the cabin fans. The button itself has a guard over it to prevent accidental activation. The system is available on all A320 family, A340/A330 and A380 aircraft.
According to the A320 quick reference guide, the ditching procedure calls for Flaps 3 and a minimum approach speed of 150 kts. The system should be activated at 2000 feet AGL and Airbus recommends 11 degrees of pitch at the time of touchdown.
The ultimate purpose of the system is to seal the aircraft to prevent water from undermining the buoyancy of the aircraft to keep it afloat in the event that the airframe remains intact after impacting the water. Federal Aviation Regulation Part 25, Section 801 describes the safety requirements in the event of a ditching:
As the aircraft was making its 'final approach' to the Hudson, the crew was preparing the aircraft and its passengers for the water landing, including, some speculate, by activating the ditching system on the A320. The button, cleverly labeled 'ditching', is located on the 'Cabin Press' section of the overhead panel shown above.
So what does that infrequently used button actually do?
When pressed, it commands the aircraft operating system to close the outflow valve, emergency ram air inlet, avionics inlet, extract valve and flow control valve. In addition, it will immediately shutdown the cabin fans. The button itself has a guard over it to prevent accidental activation. The system is available on all A320 family, A340/A330 and A380 aircraft.
According to the A320 quick reference guide, the ditching procedure calls for Flaps 3 and a minimum approach speed of 150 kts. The system should be activated at 2000 feet AGL and Airbus recommends 11 degrees of pitch at the time of touchdown.
The ultimate purpose of the system is to seal the aircraft to prevent water from undermining the buoyancy of the aircraft to keep it afloat in the event that the airframe remains intact after impacting the water. Federal Aviation Regulation Part 25, Section 801 describes the safety requirements in the event of a ditching:
(d) It must be shown that, under reasonably probable water conditions, the flotation time and trim of the airplane will allow the occupants to leave the airplane and enter the liferafts required by ยง25.1415. If compliance with this provision is shown by buoyancy and trim computations, appropriate allowances must be made for probable structural damage and leakage. If the airplane has fuel tanks (with fuel jettisoning provisions) that can reasonably be expected to withstand a ditching without leakage, the jettisonable volume of fuel may be considered as buoyancy volume.It's not hard to imagine that this live test of the 'Ditching' system was a resounding success.
on January 17, 2009 8:19 PM | Reply
A Question for the heavy metal pilots on this blog: I heard some "hangar lore" that flocks of birds will dive or divide to avoid an aircraft using its weather radar. Have you heard this? Do you believe it? HAS ANYONE HERE (any heavy metal driver) had a bird strike with the weather radar in TX mode?
I'm doing a little survey. You can email to fderfler@gmail.com
on January 17, 2009 10:05 PM | Reply
This is an old tale. Back when radar first found its way onto airplanes the units were relatively inefficient and radiated a lot of power. (Standing in front of an airplane on the ground with its radar on was dangerous)
Supposedly birds were affected and pilots were told to take off and land with the units on to try and ward off birdstrikes.
Whether or not this was actually effective is open to some debate.
on January 17, 2009 11:34 PM | Reply
Is it at all possible to ditch a jet such as this on a flat stretch of land that is not water or a runway? What option would the pilot have had if the Hudson wasn't available? You pilots are just plain cool! What a respectable career!
on January 18, 2009 6:25 AM | Reply
Latest report says the Cactus 1549 crew didn't have time to flick the switch.
on January 18, 2009 6:37 AM | Reply
The ditch switch was not activated as reported by the NTSB interview.
on January 18, 2009 10:15 AM | Reply
This isn't a ditching question, but a question concerning A320 emergency power systems. Can anybody link me to some info concerning the A320 EPU or APU? I'm having some difficulty finding any technical information concerning this. Thanks.
on January 19, 2009 4:49 AM | Reply
On a lighter note, lets hope after this it doesnt become part of the certification procedure.
on January 19, 2009 7:50 AM | Reply
According to the AP, the crew never got around to activating the ditch switch. It's near the end of the checklist, and they were a little busy for some reason. I wonder if that switch would ever have an effect anyhow, since it's not likely you'd ever ditch and maintain fuselage integrity.
on January 20, 2009 9:47 AM | Reply
What's the bedroom switch for? Crew rest or did this particular plane have a bedroom?
on January 21, 2009 5:18 AM | Reply
I am a nigerian pilot and have flown a couple of thousands of hours on the F28,B737-200Adv,and the McDonald Dauglas DC 10-30 airplane, The US AIR Airbus 310 have performed an incredible task beyond comprehension.Where ever you put man and machine,no matter what design you may think have been perfected,doesn't fuction like that in reality. The safest thing in an airplane is a well trained pilot,but even at that, I am sure you will agree with me that it is a mirracle that these captain took a decission in a split of seconds,which was the major factor in survival in the ditching.Can you imagine what would have happened had the visibility and ceiling been bad?, NTSB will carry on with their investigation,but it is my candid opinion that the crew on this flight deserve comendation not only from US-AIR,but from Country and Aviation World in general.WELL DONE FOLKS.
on January 21, 2009 5:19 AM | Reply
I am a nigerian pilot and have flown a couple of thousands of hours on the F28,B737-200Adv,and the McDonald Dauglas DC 10-30 airplane, The US AIR Airbus 310 have performed an incredible task beyond comprehension.Where ever you put man and machine,no matter what design you may think have been perfected,doesn't fuction like that in reality. The safest thing in an airplane is a well trained pilot,but even at that, I am sure you will agree with me that it is a mirracle that these captain took a decission in a split of seconds,which was the major factor in survival in the ditching.Can you imagine what would have happened had the visibility and ceiling been bad?, NTSB will carry on with their investigation,but it is my candid opinion that the crew on this flight deserve comendation not only from US-AIR,but from Country and Aviation World in general.WELL DONE FOLKS- HAPPY LANDINGS.
on January 22, 2009 5:45 PM | Reply
Sierra Hotel! To the entire Flight Crew!
on January 26, 2009 3:14 AM | Reply
Not only Airbus types, but also the MD11 has a "ditching" button on the overhead panel. Would definitely not want to try it, however!
on January 26, 2009 7:10 AM | Reply
Credit where due, and if I'm ever in such a critical situation I hope I perform as well as the US Airways crew.
But there's a lot of talk about how unique the survivable ditching was, and how unusual it is to retain fuselage integrity. Any fuselage will leak, (rubber door seals etc.) even if the ditch switch is used.
Wing mounted engines are designed to come off, and flaps etc. probably will also. But in controlled ditchings (as opposed to crash landings, runway over-runs and or CFIW), fuselages usually survive.
Examples off the top of my head include National 727 at Pensacola, Aeroflot Tu-124 at St Petersburg (river), Tarom Tu-154 off Mauretania, JAL DC-8 San Francisco bay (eventually repaired and returned to service), Trans Arabian 707 Lake Victoria, Sudan 707 River Nile with gear down. I believe the DC-9 near the Virgin Islands, another JAL DC-8 and a 727 in Tokyo Bay also remained intact with high or 100% survival rates.
Any criticism of the failure to push the ditch button is inappropriate. We are reminded every six months in the simulator of how there never seems to be enough time to complete emergency checklists. In some situations you just do as much as you can and land it regardless.
on January 26, 2009 1:16 PM | Reply
I'm sorry law of gravity, but I haven't completed my emergency ditching checklist, you'll have to wait before you can pull this plane down to the water. :o)
on January 29, 2009 12:19 PM | Reply
FYI. In reference to the comment. It's not hard to imagine that this live test of the 'Ditching' system was a resounding success.
The Ditching button was not deployed on this otherwise text book water landing. Cheers.
on January 29, 2009 12:19 PM | Reply
FYI. In reference to the comment. It's not hard to imagine that this live test of the 'Ditching' system was a resounding success.
The Ditching button was not deployed on this otherwise text book water landing. Cheers.
on February 1, 2009 8:11 PM | Reply
Sully, you dragged the LH wing a tad low, which put the LH engine in the water first. Then it started scooping water before the RH engine, the LH eng tore off, then the resulting drag slewed the aircraft anticlockwise at right angles to the river direction.
Sully, you did a rapid 'wheelie' minus the wheels for us to see!
Anyway, we all survived and thanks, it could have been worse.
on March 11, 2009 5:36 PM | Reply
>Any criticism of the failure to push the ditch button is inappropriate.
It certainly is not.
A type rated pilot ditching an airplane equipped with a specialized ditching system (quite unusual) who fails to deploy that system will go to his grave wishing he had done so. The actual 'miracle' is this situation was the presence of a river to land in, and boats thereon to rescue passengers before the aircraft sank. Sully did a nice job, but he forgot a very important part and knows it. There are going to be some awkward moments in forthcoming civil cases.
on March 12, 2009 9:19 AM | Reply
A recent special on HD Theater (Discovery HD, I believe) reviews this scenario. It should be noted that the double power loss troubleshoot procedure was said to have been written for loss of power at primarily cruise altitude (read: above the ~3000ft that it happened in this case) but also is a THREE page checklist, of which pressing the button is the very LAST item on the list.
They noted that the co-pilot got as far through the checklist as possible, but that it was nearly impossible for them to get through the entire checklist from a strike at ~3000ft.
If you haven't seen that "documentary," please do so. It's quite informative. Capt. "Sully" should still be commended, as his split-second decision making saved lives even at risk of costing others.