The year saw installation of two new chief ministers after over four months of internal strife among the members of the ruling Congress.
In one of the greatest tragedies the state witnessed in the past decades, popular chief minister Khandu was killed in the crash at Lobothang near Tawang, bordering China. The Eurocopter B3 craft ran by Pawan Hans Helicopter Services Limited, carrying him and four others went missing on April 30 shortly after take-off from Tawang.
After four days of massive search, the wreckage of the chopper along with five bodies were found at Lobothang.
56-year-old Khandu, who had served in the intelligence wing of the army, was the fifth chief minister of the state.
Earlier on April 19, a Pawan Hans Mi-17 chopper crashed while landing at Tawang helipad killing 17 people including three crew members while a pilot and other five survived with serious burn injuries.
At least 15 people died in a bridge collapse at Seppa in East Kameng district on October 29 when they were on a hunting spree to catch an insect locally known as Tari, a tribal delicacy.
Political upheavals started in the state immediately after the death of Khandu with two contenders hobnobbing for the coveted post. Immediately after Jarbom Gamlin was sworn-in as chief minister on May 5, the state witnessed a tense situation following a derogatory report published in two national dailies against the Nyishi community.
Various Nyishi organisations in the state led by Nyishi Elite Society (NES) and All Nyishi Students' Union (ANSU) waged war against the publication and demanded the state government pursue the case for a logical solution.
Aggrieved over the lackadaisical attitude of the Gamlin- led government, the organisations intensified their movement and launched a series of bandh calls and rallies on the issue which even claimed a life on October 11.
Offices of the Press Trust of India and a local daily were vandalised by unknown people in the milieu.
Dissident activities within the Congress started from the very first day after Gamlin taking over the reign of the state.Majority of the Congress legislators led by dissident leader Nabam Tuki made a bee-line to New Delhi, the hub of political power, placing demand for replacement of Gamlin for his alleged autocratic rule.
Constant pressure from the Congress legislators followed by volatile mass movement in the state by Nyishi organisations including torching of several vehicles besides damaging public property over the issue, the party high command was compelled to think for an alternative which led to the installation of Tuki as the seventh chief minister on November 1.
The oft-repeated claim of China over Arunachal territory re-surfaced during the year when two Arunachal sportsmen were prevented by immigration officials from boarding a flight to Beijing on January 12 as they had stapled visas issued by the Chinese Embassy on their passports.
Indian Weightlifting Federation's joint secretary Abraham K Techi and lifter Yukar Sibi were to visit the country at the invitation of Chinese Weightlifting Association president Menguang for the January 15-17 China weightlifting Grand Prix at Fujian province.
The denial of formal visas to the sportsmen sparked strong protest in the land-locked state with apex students' body – All Arunachal Pradesh Students' Union (AAPSU) burning effigies of Chinese Premier Hu Jiantao on several occasions. The students' body also banned sale of all Chinese products in the state during the year.
Insurgency-hit Tirap and Changlang districts witnessed a series of clashes between both the factions of the NSCN during the year.
In another significant development in both the districts, the proscribed NSCN-K during the year directed all the 12 elected representatives of those districts to withdraw support from the Dorjee Khandu ministry. The directive of the rebel group evoked strong reactions in the state with various organisations staging protests on several occasions.
The reported move of the Naga Peoples' Front (NPF), a Nagaland-based political party, to spread its wing to the state during the year also sparked strong protests.
The law and order in the state too remained grim with a series of abduction cases reported during the year.
A forest official, an FCI official and the managing director of Arunachal Pradesh Mineral Development and Trading Corporation Limited (APMDTCL) were kidnapped by insurgent groups. While the forest official was release, the body of the FCI official was recovered at Itanagar and the APMDTCL MD is still missing.
The year, however, saw two women of the state creating records in mountaineering. Anshu Jamsenpa (32) climbed to the top of the world for a record second time in 10 days. She unfurled the national flag and Arunachal logo at the summit of Mt. Everest (29035 ft) on May 21.
A mother of two children, she became the first woman in the world to make it to the summit of Mt. Everest twice in one climbing season. She had earlier made it to the summit on May 12.
Another girl Tine Mena also created a mountaineering record by scaling the world's highest peak on May 9 by just taking half packet of noodles as her food.
Lifter Hitlar Tagru also brought laurels to the state by winning three gold medals in the 6th National Youth Weightlifting Championship. The state also hosted the seventh National Youth (Boys and Girls) and 48th men and 24th women junior national weightlifting championship on November.
Longding became the seventeenth district of Arunachal after carving out of Tirap.