“Based on the available data and a close correlation of thunderstorm activity at the last received location, it appears that weather was a factor, or was a compounding factor. The most likely hazard, if weather was a factor, appears to be icing. This is only an assessment of best available meteorological information, and is not a final determination on the cause of the incident.”
Tim Vasquez / Weather Graphics
Aircraft was seen on radar at FL363 and 353kts ground speed… later on, mode-S data showed it was at FL240 at -11000fpm and just over 60kts ground speed.
The climb rates of over 6000fpm and even up to 9000fpm were recorded on the Mode-S. Sources also said that at times the aircraft exceeded -24000fpm (yes, 3 zeroes)…
The other thing is that the climb, peak, descend and disintegration/disappearance (ie: FL320 to FL360 over, to FL240 where it disappeared) took just under 1 minute and 10 seconds or so.
Aircraft turned left throughout the drama, except for the end where it tracked east varying plus minus 5 degrees… through the very fast descent rates prior to disappearance.
Now, AF447 had peaks of +9500, and -16500fpm… this -24000fpm baffles me at the moment…
The slow ground speed is the confusing part. Flat spin or a nose up fall should still result in higher ground speed even at those descent rates.
Current suspicions are:
1. an AF447 style accident with higher nose up angle (which makes little sense in terms of pilot action)
2. loss of control due to one reason or another.
3. Structural failure of some sort.
Thunderclouds were in their majority behind the aircraft.
The Jakarta Post, Jakarta – Hans Nicholas Jong
After two days of fruitless effort, the search and rescue operation discovered on Tuesday debris and bodies from AirAsia flight QZ8501 in the Karimata Strait, the waters that separate Belitung Island and Kalimantan.
The first discovery was made in the afternoon when a C-295 transport aircraft discovered floating debris in the strait.
Shortly after, an Air Force Hercules C-130 found an object casting a shadow in the ocean, thought to resemble an airplane.
Rescue workers on the aircraft also found three bodies thought to be victims of the crash at 1:25 p.m., while the Indonesian Navy warship, KRI Bung Tomo, discovered an emergency exit door at 1:50 p.m.
All of the discoveries were made within sector V, one of 13 sectors in the search and rescue area, measuring 150-by-200-square nautical miles.
“Now we are focusing our recovery process in sector V,” National Search and Rescue Agency (Basarnas) chief Air Chief Marshall Henry Bambang Soelistyo told a press conference at his office in Kemayoran, Central Jakarta, on Tuesday.
As night fell on the strait, Basarnas had recovered three bodies, he said.
“They are on KRI Bung Tomo. Two are female and one is male. They were recovered at 5:50 p.m.,” Bambang said.
Basarnas decided to halt the recovery operation after finding the three bodies because the tide was rising.
“When the tide recedes tonight, we can continue the recovery using lights from the ships. But now the tide is still 3 meters high,” said Bambang.
Basarnas also retrieved some items from the aircraft, including an aspirator assembly, a small blue suitcase and a reservoir slide craft.
AirAsia had confirmed the aspirator assembly and the reservoir slide craft belonged to the airplane, according to Bambang.
Basarnas is being assisted in the search and rescue operation by the Indonesian Navy.
“In the vicinity of the debris, we have KRI Yos Sudarso, KRI Bung Tomo, Basarnas ship KN 224. Later tonight, other ships will arrive, including KRI Banda Aceh, three Singaporean ships, KRI Pulau Romang and KRI Pulau Rengat,” Bambang said.
Also expected to join the rescue operation are sonar-equipped ships from the Agency for the Assessment and Application of Technology (BPPT) and the Indonesian Survey Association (ASI).
Earlier on Tuesday, Reuters reported that 40 bodies had been recovered from the sea. The news agency quoted Col. Manahan Simorangkir, a spokesman for the Navy for the report.
The misreporting prompted Indonesian Military (TNI) Commander Gen. Moeldoko to issue a statement saying that all information regarding the rescue operation would come from Basarnas, which was in charge of the whole search and rescue operation.
Moeldoko also stated that all military assets, including ships delivering logistics such as fuel, would be under Basarnas.
“We will deploy helicopters to take the bodies [from the sea to the ships],” he told reporters on Tuesday.
Moeldoko said that the Navy also had 47 divers, 11 of whom had been deployed on Tuesday to help Basarnas’ 10 divers.
The bodies and jet wreckage, once they could be retrieved, would be transported to Pangkalan Bun in Central Kalimantan.
“There, we have prepared coffins. Then the bodies will be transported on Hercules aircraft to Surabaya. […] The bodies will be identified there and returned to their families,” Moeldoko said.
In Surabaya, President Joko “Jokowi” Widodo said that the recovery operation would solely be focused on retrieving the bodies.
“I have given orders to focus on the recovery of both passengers and crew. Right now, just focus on the recovery,” Jokowi said in a press briefing at Juanda International Airport.
“There is a recent development however that relates to Airbus A320 series aircraft. A December 10, 2014, Airworthiness Directive (AD 2014-25-51) describes how control of the aircraft could be lost in flight as a consequence of icing of the angle-of-attack probes and an interaction with the airplane’s stall protection function.
Those probes act like small weather vanes on the side of the aircraft and measure the angle at which the airplane moves through the air — the angle of attack. If the angle is too high the air can no longer flow smoothly around the wings, resulting in an aerodynamic stall. The acceptable range of angles of attack is fairly small, and gets considerably smaller at higher speeds, such as cruise speed.”
“Simply put, depending on the position of the angle-of-attack probes when freezing occurs and the subsequent speed of the aircraft, the system may be fooled into thinking that the aircraft is approaching a stalled condition — even when it isn’t. In response, the airplane’s stall protections pitch the aircraft’s nose down to recover. This erroneous pitch down cannot be overridden by the pilots unless an emergency procedure in the Airworthiness Directive is followed. All pilots flying this model airplane should be aware of this.”
“The procedure instructs the pilots to shut down two of the three air data computers to render the usual stall protection inoperative and allow recovery of the aircraft…”
Bill Palmer, Airbus A330 captain, author of “Understanding Air France 447
“In total we have recovered 30 bodies; 10 bodies have been flown to Surabaya [East Java], four are in Pangakalan Bun, seven are on [naval vessel] KRI Bung Tomo, one on [Malaysian naval vessel] KD Pahang and eight bodies are in Surabaya,” Bambang told the press on Friday evening at Basarnas headquarters in Central Jakarta.“We have also recovered debris from the plane, but I won’t go into detail.” The team also detected the presence of aviation turbine fuel (avtur) in the search area. He said the joint Search and Rescue (SAR) team was being challenged by bad weather in the operation, such as strong winds and high waves.
JAKARTA: Two big objects were found in the search for Indonesia AirAsia flight QZ8501 on Saturday, Indonesia’s search and rescue agency chief said.
The two objects are about 30m under water and located near an oil slick spotted Friday, said Basarnas chief Bambang Sulistyo.
The first object measured 9.4 meters by 4.8 meters by 0.4 meters (30 feet by 15 feet by 1.3 feet), while the second is 7.2 meters by 0.5 meters (24 feet by 1.6 feet), he said.
“With the discovery of an oil spill and two big parts of the aircraft, I can assure you these are the parts of the AirAsia plane we have been looking for,” he said.
“We are lowering a ROV (remotely operated underwater vehicle) underwater to get an actual picture of the objects detected on the sea floor. All are at the depth of 30m,” Soelistyo said, adding that a strong current was making it difficult to operate the ROV.
Three vessels sent out to a sea area where the oil slick was spotted located the “two objects…that are close to each other,” said Soelistyo.
“…As you can see, the lines are well correlated until the final squawk, where the reported airspeed is 469 kts and the average ground track speed is calculated at 264 kts.
This points strongly to Pitot tube icing, and the aircraft stalling as it attempted to climb.
I have uploaded the raw data here: Google Drive…”
Interesting Internet Chatter
Q: I noticed all the cargo was in bay #3 near the wings. Any chance of a sudden shift in CoG owing to a failure in the nets caused by heavy turbulence resulting in a loss of control? Similar to US 5481?
A: I had the same thought, but the numbers don’t bear this out. The 1.3 tonnes of baggage could move at most 8 meters aft, shifting the CG of the 60+ tonne aircraft by about 1/6 of a meter, a tiny amount that is well within the range of acceptable trim. It would certainly not result in a rocket climb.
Q: Does the 6k-9k fpm ascent rate work against the on-board-explosive theory? I have a hard time seeing how an explosion would be followed by a climb rate 3-4x greater than can be commanded.
A: Please think for just a minute of the balance of an airplane
– Forward of CoG : the cockpit / the front cabin / the equipment bay / the forward cargo hold / the engines and part of the fuel.
– Aft of CoG : the aft cabin / the aft cargo hold (s) / the tailplane and fin / the APU. The tailplane has generally an upward moment ( hence a nose-down effect ) to balance the wing lift in flight.
Hence the loss of the tailplane can be associated with a pitch up moment.
Q: If I read Pihero’s explanation about weight distribution right, CoG would move backward leading to a nose up attitude. Since the wings certainly provide much more lift than the stabilizers
A: Normally the horizontal stabilizer will produce downforce, not lift. More precisely, lift in the downwards direction.
Q: That requires a downward force on the tail, and would result in a nose down motion if the tail is los
A: You are of course very right. Typical brainfart for thinking too fast. On modern airplanes, we can move the CoG far enough for the tailplane to generate lift (a la A330, for instance ) Not generalised and not on the 320.
Mandala499’s above post depicts an altogether different scenario : fast climb to 36 000 ft +, followed by a rapid – very rapid descent, a continuous heading variation to the left.
FWIW, LTC8K6 had already given the climb rate : 8600 ft/min a long time ago.
Mandala499 goes on saying that the whole SSR event lasted 1 minute and 10 sec, descent rates reaching 24 000 ft/min.
We can now derive that :
FL 320 to FL 360 = 4300 ft in less than 30 sec –> vertical speed of 8600 ft/min
time left from 36 300 ft to 24 000 ft = 40 sec –> 12 300 ft in 40 sec –> vertical speed 18 450 ft/min average, or 182 kt
Recorded ground speed : 60 kt says Mandala499. That means, the fall was on a trajectory just 20° from the vertical.
182 kt is not terminal velocity, so it’s not a dive… more a falling leaf-type of situation… which means a major structural damage : wing (left wing probably) and flight controls.
Therefore there are two probable causes left:
1/- A freaky, violent encounter with a monster updraft which is not backed by study of the ITCZ weather in the zone at the time of the accident…
2/- An explosion / sudden violent fire… We might well be seeing the effects of a bomb here.