[8][9] The flight was normal until 06:00 when an electronic centralised aircraft monitor (ECAM) memo was displayed, along with a master caution light, to indicate a fault with the rudder limiter system.

[7](pp14–15) At 06:11, the pilots turned fifteen degrees to the left to avoid inclement weather, and contacted Jakarta ATC to request a climb to FL 380 at 12,000 metres (38,000 ft) for the same reason.

(p17) Its last recorded position was over the Java Sea, Karimata Strait between the islands of Belitung and Kalimantan (3°22′15″S 109°41′28″E / 3.3708°S 109.6911°E / -3.3708; 109.6911 (AirAsia Flight 8501 last transponder signal)).

A memorial service was held alongside the presentation of the award, and was attended by the Consul General of Indonesia for Victoria and Tasmania, Dewi Savitri Wahab, 40 of the deceased's friends and representatives from the Indonesian Student Association in Australia (PPIA) Monash University branch.

[36] On 28 December 2015, the first anniversary of the crash, a private prayer service was held in a room in the Mahameru Building of the East Java Regional Police, Surabaya, and was attended by relatives of the victims, as well as by the Head Chief of the Search and Rescue Agency, Henry Bambang Soelistyo.

By 30 December naval and air units from Singapore, Malaysia and Australia had joined Indonesian authorities in patrolling designated search areas.

Singapore's Ministry of Transport provided specialist teams from the Air Accident and Investigation Bureau and underwater locator equipment.

[57] More than ninety vessels and aircraft from Indonesia, Singapore, Malaysia, Australia, South Korea, Japan, China, the United States, and Russia participated in the search.

[58][59][60] This fleet included three ships with underwater detectors and two fuel tankers seconded to ensure efficient operation of the vessels in the search area.

"[70][71][72] Another fisherman reported that, while moored on Sunday at Pulau Senggora, south of the town of Pangkalan Bun in Central Kalimantan, "Around 7 am, I heard a loud booming sound.

"[73][74] The fisherman's reports, delivered after he had returned home the next day, were credited with guiding the search-and-rescue team to the vicinity of the crash.

[73] The first items of wreckage were spotted by search aircraft on 30 December in the Karimata Strait, 10 km (6.2 mi; 5.4 nmi) from where the crew last contacted air traffic control,[75][76][77][78] and three bodies were recovered by the warship KRI Bung Tomo.

[85][86][87][needs update] The head of the Search and Rescue Agency also denied the existence of any sonar images of the wreckage (as well as the reported recovery of a body wearing a life vest).

On 2 January 2015, Basarnas reported evidence of a fuel slick on the water surface in the search area, but detection of the fuselage remained unconfirmed.

[citation needed] By March 2015, all large pieces of fuselage from the jet had been lifted from the seafloor and moved for investigative purposes.

[113] The loss of Flight 8501 also brought attention to the lack of weather radar at Indonesian air traffic control centres.

[114][115] According to the Toronto Star, "Indonesia’s aviation industry has been plagued with problems ... pilot shortages, shoddy maintenance and poor oversight have all been blamed following a string of deadly accidents in recent years.

"[110] The West Kotawaringin Regency administration in Central Kalimantan planned to build a memorial for the AirAsia flight that also doubles as a monument for aviation safety.

Central Kalimantan deputy governor Achmad Diran stated that the monument is also going to be the symbol of gratitude and appreciation for the efforts of the National Search and Rescue Agency.

West Kotawaringin regent Ujang Iskandar said that with the monument, "we hope that the families and the government will lay flowers every 28 December, and continue the dialogue on aviation safety in Indonesia.

"[116] On 22 March, Indonesia's search and rescue agency's head, Bambang Soelistyo, families of the victims and AirAsia officials visited the crash site to spread flowers and hold prayers.

[118] The family of the first officer, a French national, have filed a lawsuit against AirAsia in connection to the lack of permission to fly on that day, claiming the airline was "endangering the life of others".

[needs update] The head of Indonesia's Central Statistics Agency (CSA) Suryamin attributed the decrease to the revocation of a number of flight licences in the wake of the accident.

[131] Tatang Kurniadi, head of Indonesia's National Transportation Safety Committee, stated that sabotage was ruled out as a cause of the accident by the black boxes, and a preliminary report was supposedly submitted to the International Civil Aviation Organisation by early February.

[citation needed] After studying the wreckage of the Airbus A320-216 as well as the two black boxes and the cockpit recorder, Indonesia's National Transportation Safety Committee issued a report with their conclusions from the investigation on 1 December 2015.

The report stated that the sequence of events that led to the crash started with a malfunction in two of the plane's rudder travel limiter units (RTLU).

Investigators also found that, just moments earlier—on the fourth occurrence of the RTLU warning during the flight—the captain chose to ignore the procedure advised by the ECAM instructions, and, instead, left his seat and reset the circuit breaker of the entire FAC,[133][138] unintentionally disengaging multiple flight control systems, which would have to be turned on by the pilots after the circuit breakers are reset.

Without the FAC's computerized flight augmentation, pilots would have to "rely on manual flying skills that are often stretched during a sudden airborne emergency".

[141] When the crew was required to fly the Airbus A320 manually, there was an unexplained nine-second delay between the start of the roll and either pilot attempting to take control.

[143] The report did not specifically conclude that pilot error caused the crash[144] while detailing the chain of events leading to the loss of Flight 8501.