Martin Johnson, 56, from Harlow, Essex, made the threats on an easyJet flight from Bristol to Malaga in April.
Bristol Crown Court heard he bought two bottles of duty free wine and drank one before boarding and the other on the aircraft.
The flight had to turn around and return to Bristol.
The court heard cabin crew found an empty wine bottle in the toilet and that someone had urinated all over the cubicle.
Johnson became abusive after they announced the flight would be returning to the departure city.
"If the pilot turns us around I am going to stab him and I am going to hit him," he said.
"I'm going to stab an air hostess and kill everybody on the plane."
Johnson, originally from Scotland, was arrested when the flight landed after it had turned back 25 minutes into its journey.
The court heard his behaviour caused disruption to many of the 153 passengers on board, whose holidays and travel were delayed, and it cost easyJet tens of thousands of pounds.
Representing himself, he denied he had threatened to stab anybody and said he was not violent.
Sentencing him, Judge Michael Longman said his behaviour would have caused "fear and alarm" to passengers.
"The vast majority of aircraft passengers are sensible and law abiding and when people act irresponsibly and idiotically like you did, sentences of imprisonment will always be required.
"I take into account there was no physical violence although the oral threats were bad enough.
"In the circumstances there must be a sentence of immediate imprisonment."
Johnson, also known as James Kelly, has been given a lifetime easyJet ban.

Police said the man was assaulted on Friday night in the car park of The White House, a Wetherspoon pub in the Leicestershire village of Scraptoft.
Emergency services were called to the pub at 22:10 BST and the man was taken to hospital where he died.
The 23-year-old man who was arrested is in police custody.
Tributes have been left near the door of the pub.
Police have appealed for anyone who witnessed the assault or events leading up to it to contact them.
A drunk aeroplane passenger who threatened to stab the pilot and everyone on board has been jailed for eight months.
[NEXT_CONCEPT]
A man has been arrested in connection with the death of a man who was assaulted in a pub car park.