Timeline of flight QZ8501
6.36am (Singapore time; 5.36am Surabaya time)
AirAsia Indonesia Flight QZ8501 takes off from Surabaya's Juanda International Airport. It was scheduled to take off at 6.20am Singapore time. It goes to 32,000 feet and is meant to take the expected flight path M635.
7.12am (Singapore time)
In the plane's last contact with air traffic control, the pilot requests to divert from the flight path to avoid poor weather. It also requests to climb to 38,000 feet. Air traffic control agrees.
7.16am (Singapore time)
Indonesian air traffic control is still able to detect the plane on radar.
7.17am (Singapore time)
This is when the plane loses contact with air traffic control, said Mr Djoko Murjatmodjo, the director-general of aviation at Indonesia's ministry of transportation.
8.08am (Singapore time)
Incerfa - also known as the Uncertainty Phase, when the time of last contact between an aircraft and air traffic control exceeds 30 minutes - is activated.
8.28am (Singapore time)
The next phase, Alerfa, also known as Alert Phase, is activated.
8.55am (Singapore time)
The aircraft is considered to be in Detresfa, or Distress Phase, and is officially considered missing. During this phase, search operations are activated.
1.48pm (Singapore time)
Indonesia news portal Detik.com reports Indonesian Transport Minister Ignasius Jonan as saying that search operations are being focused on an area off East Belitung. Unconfirmed reports of the plane crashing in the area emerge.
3.58pm (Singapore time)
AirAsia boss Tony Fernandes tweets that he is flying to Surabaya, where the passengers' next-of-kin have gathered at Juanda Airport. In Singapore, next-of-kin are briefed in a holding room at Changi Airport Terminal 2.
4.29pm (Singapore time)
The Civil Aviation Authority of Singapore says Indonesia has accepted Singapore's offer to assist in search-and-rescue operations. Singapore launches one C-130 aircraft for the search.
6.30pm (Singapore time)
The C-130 reaches the search area.
7.25pm (Singapore time)
Indonesia announces it is halting search-and-rescue operations for the night due to poor light and weather conditions. Operations are expected to resume early today. The Singapore air force will send two C-130s for the search today.