Not so.

The FAC's are switched off by using the switches on the overhead panel.

The sidesticks will work perfectly

You'll be in ALTN Law with protections lost. Direct Law with Gear Down. You will NOT be in mechanical back up.

If you were to turn off all ELACs and SEC's you will be in Mechanical Back Up.

Datum, as per your question regarding an engineer taking a revenue seat this simply is not the case if the aircraft is full we would occupy a cockpit jump seat, and I have done in numerous occasions.

International Business Times reports:
 

“....Signals from the black box of AirAsia Flight 8501 were detected Wednesday near where the plane's tail has been located in the Java Sea, but the pings were later lost, Indonesian Armed Forces Commander General Moeldoko said Thursday. Authorities reportedly said that the recovery of the tail section, where the flight recorders are typically located, is underway...".

I am still struggling to fully understand what we can see in the pictures.
The outside pictures quite obviously do show the fuselage skin forward of the aft pax door, and the VTP (you can see the "i-dot" of "Air").
For the internal picture I am still unsure what we can see.
No, it is an A300 picture...
The item on the left side looks like a bleed air duct wrapped in insulation material (APU bleed line), the milled part is round on the left edge, so it can not be part of the HTP spar box, it looks more like an upper VTP attachment frame, the fitting is too long to be the trim actuator fitting. On the left side it looks like a lot of wires and connectors.

And for the other Airbus discussion...
100% correct. The stabilizer trim will never do something without a pilot input (either to the computers or via sidestick or trim switch) triggering this action, however....
This is wrong.
This is wrong as well. Please have a look at the available FDR data first. What triggered the trim movement was several short nose up inputs during a time during which the main inputs were left-right. The 4 minutes of stick back (a shorter, but still extremely long time even full back) were applied after the trim had already reached the full nose up stop, when basically all was done already, and the nose was even dropping below the horizon, which can somehow explain why full nose up inputs were given at that time. This does not mean, the systems brought down this plane, of course it was the pilot doing unbelievable errors in understanding the situation and steering the plane ignoring all procedures and hand flying basics. But he was not acting as stupid as it sometimes is stated in an enormously simplified version of the event.

For the time being I can see no link between both cases, except that it happened over water with severe thunderstorm activity in the area. But this time it was early dusk, not pitch dark night. I find it highly unlikely that similar attitude deviations remain unnoticed if you have some outside reference. I find it highly unlikely that a climb was not noticed, when such climb was requested but explicitly disapproved by ATC.

If hoistop (post 1472) is correct, and the THS is full nose-up, then this would link it with both AF447 and XL Airways Perpignan crash. In both those cases the THS motored full nose up before the a/c switched to Alternate Law and the auto trim was disabled. In neither case (none of the cases?) did the pilots seem to realise the THS setting.

Those who seem to think reaching up & switching off ADR's FAC's etc in short order have obviously never been caught in a CB. The aeroplane is like a bucking bronco & pulling significant + - G. Getting your hands/ fingers anywhere near the appropriate switch is well at best a challenge or nigh impossible.

I sometimes wonder if the chaps at the front during these kinds of accidents weren't thinking " Holy moly this is a can of worms.....I know how to fly, I know what to do if I'm nose down or stalling......but what the hell is happening? ....I don't know what the truth is here, it's impossible to tell".
By that I mean that it's easy to sit here and feel like you would have behaved differently, and I would like to think that I would be able to fly a pitch and a power until I made sense of things....but would I? Would you? With the g force and the conflicting information I wonder if a mental overload situation is almost inevitable with certain types of failures in the bus.
All I know is that I'm grateful that I'm old enough to have done a fair whack of hand flying transport aircraft and that I'm on a 737 that is pretty basic. If not for those two things I don't know I would be any more able to keep my passengers safe than the folk on AF 447 or Air Asia 8501. It sure is interesting times.

Prop Duffer

No, balloon idea was reported by Channel News Asia in their blog, however attempts were suspended due to strong currents. More bodies in the water were unable to be retrieved because of currents and poor visibility.

I will be interested to see if there's any mention of the balloon idea in the day's official summary from Indonesian authorities. It is possibly to allow release from mud so that a crane can then be employed.

'Balloons' AKA salvage air bags
 

Air bags are commonly used for lifting wrecks <100t. EG. SHIP SALVAGE AIRBAGS

I thought the reference was to blimp type balloons, I know there are people trying to sell the idea but I don't know if they have anything operational. But you're probably right, this is probably about buoyancy devices.

Raising heavy things off the bottom with buoyancy floats is a very tricky business. One major problem is that while you may need a lot of lift to unstick it, once it starts rising, the air in the balloons or whatever expands. So just when you want things to go slow, the natural tendency is for things to speed up to the point of getting out of control.

But if they just wanted to raise the empennage 30 feet or so for divers to be able to get at the data recorder location, that might be doable on short notice. But even that would require experienced experts and equipment that probably doesn't exist in Indonesia.

(There is a very interesting story surrounding the recovery of the US submarine Squalus in 1939. The first time they tried to raise it, it went out of control on the way up and the bow was at least 30 feet in the air before it reversed direction and sank again, breaking all the cables and destroying most of the salvage equipment.)

Since not everyone reading this discussion is an Airbus pilot, or even a large jet pilot, it might be useful to make a brief comment about the flight control modes in the Airbus A320. The "Normal law" that is referred to is when the aircraft control computers are applying the maximum software protection to keep the aircraft both stable and within flight envelope safe limits. "Direct Law" offers protections but in a less aggressive way, and there are several "Alternate law" flight modes with little envelope protection. A reasonable summary is in the wiki page at Flight control modes - Wikipedia, the free encyclopedia. The control system will switch to lower protected flight modes if there are major failures in the current mode, but pilots can also elect to change mode. Current Airbus pilots may wish to add to this for more useful information regarding how this may be related to the current accident scenario.

Also there is a recent BBC report containing a video showing the current plan to retrieve the tail section using airbags as an assist at http://www.bbc.co.uk/news/world-asia-30723462

Markat,

Thanks. I've carried plenty of staff in jump seats too.

Was the flight full?

Why was an aircraft engineer needed to conduct a standard aircraft turnaround, or was the engineering support there to carry out non-routine maintenance also?

Did the maintenance action affect flight controls and/or air systems (pitot, static, aoa etc)?

Why was the POB mentioned by crew as 161, which differs to the POB discussed by Indonesian authorities /AirAsia and now the global media at 162?..

What was missed and why?..

All seems to be a non event. I think it may be significant

This may be a little unfair on the crew. They were well below the tops of the storms that they were in close proximity to. They could have been in IMC in surrounding small cells that may not show on weather radar. They could have been in a dark grey goldfish-bowl with severe turbulence and no visual reference. Add in lightning flashes from below and above and ECAM playing all the alert alarms, possibility that the aircraft dropped out of Normal Law unnoticed with everything else going on - and you have a recipe for complete cognitive overload.

Perhaps someone could use a military style full motion simulator that can give +/- relatively high G, but with modern aircraft cockpits - both A and B - and then put the HF engineers, pilot SMEs and designers in the cockpit and replay some known incidents like AFR447 etc., so that they understand the problems they can cause. There are times when letting multiple subsystems shout urgently to the crew is totally counterproductive.

CNN reports:
 

Sunday (Local time in Indonesia)

5:36 a.m. -- AirAsia Flight 8501 takes off from Surabaya International Airport in Indonesia.

6:12 a.m. -- Pilot asks air traffic control permission to avoid clouds by turning left and ascending to 38,000 feet.

6:16 a.m. -- Flight 8501 is still visible on radar.

6:18 a.m. -- The plane disappears from air traffic control's radar. (AirAsia reports a slightly different time, 6:24 a.m., for when contact with air traffic control was lost).

7:30 a.m. (8:30 a.m. Singapore time) -- This is when Flight 8501 was scheduled to land in Singapore.

7:55 a.m. (8:55 a.m. Singapore time) -- Flight 8501 is officially announced as "missing." Its last known position is in the Java Sea, between Belitung and Borneo.

This timeline has some additional important info. Still missing is what time the aircraft was observed to be climbing through FL363 out of control without an ATC clearance.


06:12

- QZ8501 requests left deviation from airway. Deviation approved.
- Pilot then requests climb to FL380
- ATC asks pilot to standby, due to nearby traffic and to coordinate with next sector (Singapore)

06:14

- ATC calls QZ8501 to approve climb to FL340
- No response received after 2 or 3 further attempts to contact
- ATC requests help from nearby aircraft to contact QZ8501

06:16

- ATC still cannot reach QZ8501
- Aircraft still observed on radar screen

06:17

- Radar contact lost
- Last reported altitude: FL290

There has been some discussion here about what some are calling 'Paint Scrapes', along the middle of the A .


If you look closer at the A, you will see that the lower part of the A is curved inwards, and so is the upper part of the A . This indicates that the whole side of the aircraft has been subjected to some pressure, caused by its impact with the water. The line of no-paint is actually a fold line.


The Aluminium will have actually deflected more than that, but sprung back to its present position, as elastic deformation has taken place.
So the paint surface will have been subjected to much more bend than is currently visible.


Anyone with a knowledge of the yield strength of the actual Aluminium used (possibly Duralumin.) would be able to give the exact figures of how far the panel would have moved, to recover to its present position.

Can someone with diving/SAR experience comment on the fact that underwater currents of 3-5 knots continue to hamper divers from entering the tail section of the aircraft or proceeding with salvage attempts/body recovery? (Although two bodies were successfully recovered today, others could not be.) It appears that whether the weather is adverse or favourable, the current is not going to change in a hurry. What is the best way forward in this situation?

I've dove open circuit to wrecks in varying currents. Max depth for me has been 100 meters. An OC diver can swim about 0.5 kts, with a good scooter, about 1 kt. The high current dives can be arranged by arm over arm with a planted anchor. Moving off the line in 3kts or greater will not allow return to the anchor line. The other technique for OC targeted dives is to be dropped off upcurrent. This saves your arms, but you might end up "flying" by the target at speed. If lucky, you can head for a protected wreck assembly that shields you from the current. Moving upcurrent is essentially not doable above 4 kt current. The issue is the bottom type. Even if sandy, 3kt currents cause "sand storms" at the bottom, limiting visibility.
Wreck diving in high current is brutal. I've had marker buoys 30 inch diameter be dragged all the way to the bottom, collapsed by water pressure, submerged by current.

Just wanted to add the fact that the aircraft was at cruise altitude for approx 30 mins with outside temps somewhere between -30/-40 and the water surface temperatures have been reported around 85 degrees F. These rapid temperature changes will impact the metal expansion/contraction along with the pressure difference between flight altitudes of 30,000 ft plus and 100ft on the sea bed that occurred within mins.

As someone with some ( quite a while ago) aircraft engineering and much more recent diving experience I would agree with a previous poster and say that the "scrape lines" people keep referring to do indeed look like seaweed rather than scrapes on the paint. That said, there is a significant buckle to the aluminium in those photos and suspect that this is due to the impact on the surface of the sea from altitude.


Regarding the body recovery. A 3-5 knot current is quite significant when diving. Great if you want to go long distances with little or no effort but a real bitch if you are trying to swim against (or across) it as they would need to do to get into an opening. There is a real danger that you will get bashed against jagged metal in this case and that is not something you want to happen when you are 100ft under the water.

Thanks for fleshing out the timeline. A couple of questions.
1. Is the part in italics a known fact, or a best estimate from information so far available? :confused: (That the overall case here is an upset seems a valid baseline).
2. Where in that timeline does the data point of FL 363 fit in? Was it in or around the 06:16 time in the timeline below or before that? I ask with the following possibility in mind: The crew hears the approval to climb to FL340 and initiates climb but is already a bit busy with controlling the aircraft as they are having significant trouble with the weather at this point.

Quote:

---

06:12
- QZ8501 requests left deviation from airway. Deviation approved.
- Pilot then requests climb to FL380
- ATC asks pilot to standby, due to nearby traffic and to coordinate with next sector (Singapore)
06:14
- ATC calls QZ8501 to approve climb to FL340
- No response received after 2 or 3 further attempts to contact
- ATC requests help from nearby aircraft to contact QZ8501
06:16
- ATC still cannot reach QZ8501
- Aircraft still observed on radar screen
06:17
- Radar contact lost
- Last reported altitude: FL290

---

scratches around letter A
 

I doubt that scratches are the result of deformations in elastic range.
Scratches are as large as pitch between two rivets, an elastic deformation of this size is not possible. Metal sheet would give for sure under buckling or shear stresses
I guess scratches are the result of impact dynamics.

The leaked photo of the radar screen does not have a time stamp so we can only guess what the time was as they were observed climbing through FL363. (out of control without an ATC clearance) Somebody knows the time but they have chosen not to tell us.

They probably never heard the clearance to FL340 at 06:14 as they were already fighting severe turbulence.

Roseland and others, please note that after geting better image I revised my post #1472. THS position could not be determined from that picture. Will try to get in an A-320 tail to have a look and compare.
"Baloon" for lifting is actually a device, used underwater to lift things off the bottom to the surface. It is shaped like something between parachute and hot air baloon and filled with air from the bottom. Cannot lift things out of the water, you need crane for this. This device will change shape, fluff in the stream of water and lose air, so not much use if currents are strong-could even act like parachute and drag the whole thing downstream.
hoistop

For those interested a very grainy video of this morning's dive efforts to inspect the tail section of the wreckage is available here. The letters PK come into view, but difficult to gain much more information from it.

LIVE BLOG: AirAsia flight QZ8501 crash, Day 12 - Channel NewsAsia

USA Today reports:
 

“.....Divers looking for the black boxes on Thursday were unable to make it past currents and 1-meter (3-foot) visibility, said Soelistyo.

He said efforts will be intensified Friday to lift up the tail — either by using lifting balloon or crane.

Ping-emitting beacons in the black boxes still have about 20 days of battery life, but high waves had prevented the deployment of ping locators, which are dragged by ships.

Six ships with ping locators were in the search area in the Java Sea, said Nurcahyo Utomo, an investigator of the National Commission for Transportation Safety.

Based on pictures taken by divers, he believed that the black boxes were still attached to their original location in the plane's tail.

"Once detected, we will try to find and lift up the black boxes as soon as possible," he said...."

Aside from the fact your use of the words "airbus conspiracy theorists" is overly judgemental with regard to a persons motivations, I concur with your thoughts. This is a different accident than AF447 and the Perpignan accident and it almost certainly happened differently.
We do have a few facts now. The trick is to recognize the difference between facts and speculation.
Some of us feel that the ability of an Airbus to auto-trim nose up after the activation of stall warning (in Alternate Law) needs further examination. I for one will be watching the data like a hawk to see If that is a factor in this accident.

Michael Phelps managed 47.51 seconds for 100m freestyle. That is fractionally over 4 knots, for 100m only, by a top class athlete in a heated indoor pool.


In human terms it's a powerful, dangerous current.

I am a diver. 3-5 knots is a TON of current. In 3 knots you would have to swim very hard just to hold position. 3 knots is actually over Vne for most divers with all the gear on. I have done a dive called "The Current" near MYEH where the current runs 5-8 knots. It is a total thrill ride and obviously the boat goes to meet you at the other end. You come up on obstacles FAST and trying to work around anything with sharp edges or places that could trap you in that current would be :eek:
In 5 knots it would take a fair amount of strength to just hang on to a line and you would be streaming from it horizontally like a flag.

The flying equivalent would be trying to hover a helicopter in winds at 120 knots gusting to 150.

@Blake777
Can someone with diving/SAR experience comment on the fact that underwater currents of 3-5 knots continue to hamper divers from entering the tail section of the aircraft or proceeding with salvage attempts/body recovery? (Although two bodies were successfully recovered today, others could not be.) It appears that whether the weather is adverse or favourable, the current is not going to change in a hurry. What is the best way forward in this situation?

Not a diver but can understand the difficulties in 3+ knot currents. What is puzzling me, despite the constant droning of the media over how swift these underwater currents are, we are treated with video (like the one graciously posted lower last page) that appears to show the opposite. Divers meticulously poring over the tail section, with silt in the flashlight beams not really moving much at all, their exhausted gases rising vertically, and normal breathing ... in a nutshell it appears to be more similar to a training dive in a pool somewhere. What gives?

It is entirely possible to have a surface current of 5 knots and 0 knots near the bottom. If that is the case, the easiest thing to do is grab the anchor line of the boat you are diving from and follow it to the bottom and reverse process to get back up.

Sites that are subject to strong currents are usually dived at slack tide - when the tide is changing direction - this period may only be minutes in duration. I'm not familiar with tides/currents in the crash site area but I'd hazard a guess that slack time is a limiting factor here. As has been stated before, complex recovery operations in 3-5 knots is not really viable.

A mental overload is almost inevitable in any type of aircraft if you are flying it in a condition you never did before, never thought about before and never trained in the sim...

If the diver would have switched off the autofocus, there might be actually something to see in the video... This way it is absolutely useless.

They maybe using scuba "safety stop anchors" to keep then in one place. I have dove in that region of the world and with currents as such. There have been many scuba accidents where the divers were swept out to sea by the currents such as these divers are facing. Another factor is the deep dive air mixture/required surface rest time (these divers typically use different air then a regular diver with those depths so that they can stay down longer) & fatigue for the divers such as cold temps at 100ft/sleep/stress/PTSD which is common for these rescue divers to have to deal with when retrieving bodies, so it is possible they are waiting for the right forecast conditions vs fatiguing their divers. There are 90 navy/commercial/certified rescue divers on this mission, that sounds like a lot of divers but it’s not when you are dealing with a complex mission & required surface rest time.

FWIW re photos-video underwater and Black boxes
 

Since we can see a few windows - that section is in front of the aft pressure bulkhead. Some of the fittings may be aft( immediately behind the pressure bulkead ) AFIK and willing to stand corrected, the black boxes are typically mounted in structure which is AFT of the bulkhead. Which may mean that the black boxes are NOT on that section or are as suspected buried in the mud.
If on a section detached from the bulkhead, the Boxes could well be a few miles away ??

This picture is of the area behind the bulkhead.

https://pbs.twimg.com/media/B6uuKqJCQAE-jnC.jpg

But it may be that the point where the plane broke apart is exactly where the recorders are.

Edit: - Just like AF447

I don't know whether this photo has been posted before, but I have only just seen this on a Twitter feed. It appears there is not much left of the tail section after if the letter ' Charlie' of the aicraft's registration.

http://i59.tinypic.com/3010m1g.jpg

Source: Twitter

It looks as though it broke away just between the rear doors and the last of the windows - roughly where the lavatories are, and around a 'fault line' in the structure according to this diagram:


http://www.spiritaero.com/assets/0/3...a7b050c731.jpg


though I doubt that is completely to scale.