When and where was the first plane hijacking?

The first recorded aircraft hijack was on February 21, 1931, in Arequipa, Peru. Byron Rickards flying a Ford Tri-motor was approached on the ground by armed revolutionaries. He refused to fly them anywhere and after a ten day stand-off Rickards was informed that the revolution was successful and he could go in return for giving one of their number a lift to Lima. Most hijackings have not been so farcical.

Guinness lists this incident as the first hijack of an aircraft.

The first recorded aircraft hijack was on 21 February 1931, in Arequipa, Peru, when Byron Rickards (USA) was flying a Ford Tri-motor from Lima, Peru to Arequipa. Once landed, he was surrounded by soldiers and told he had just become the prisoner of a revolutionary organisation, but was later released on 2 March of the same year.

http://www.guinnessworldrecords.com/world-records/first-hijack-of-an-aircraft/

The Peru hijacking only involved the pilot's being captured when he was on the ground. According to this site:-

"July 16, 1948. A Catalina seaplane, operated by Cathay Pacific and christened "Miss Macao", departed from Macao and was bound for Hong Kong. A little while after take-off, three armed men entered the cockpit, and one of them asked the pilot to give him the controls. Pilot's refusal cost him his life, as well as the life of the other passengers. The pilot's wounded body fell on the control stick, making the plane dive into the sea. Out of the 27 occupants, only one survived and ironically, it was the leader of the terrorist group, which hijacked the ill-fated plane."

http://www.hindustantimes.com/india/plane-hijacking-reality-of-aviation-life/story-2sQ5N5SncVMXyWdkP0PoIP.html

In addition to the above, Wikipedia lists many notable hijackings.

https://en.wikipedia.org/wiki/List_of_aircraft_hijackings

The oldest one listed there was on September 25, 1932 and involved a Panair do Brasil Sikorsky S-38.