Col Roberts, 51, from Passfield, Hampshire, had to be restrained by five passengers and handcuffed with plastic ties. But after hearing that he had no recollection of his behaviour
and was being treated for post-traumatic stress disorder after witnessing scenes after the tsunami in southern Thailand, the jury cleared him of the charges.
Speaking outside court after the verdict, his lawyer, Look Chih Wang, said: "Colonel Roberts has been found not guilty of this offence because he was not in fact drunk. His behaviour was due to a temporary abnormality of function caused by long-term chronic stress, tsunami-related post-traumatic stress, sleep deprivation and a combination of the anti-depressant Seroxat and alcohol.
"Colonel Roberts has been advised by his doctor that he could drink in moderation whilst taking Seroxat and has maintained his innocence throughout these proceedings. The Crown Prosecution Service have been in possession of the defence expert's reports in this case for many months. It is therefore perhaps surprising that this matter was ever brought to trial."
But he said his client wanted to apologise for his behaviour and the alleged remarks and stress that they were in no way representative of his views or beliefs.
Col Roberts, who helped identify British victims of the tsunami, had been on his way back to London to brief colleagues when the incident occurred. The court heard the former army helicopter pilot had been seen drinking whisky at the airport and had gone on to consume at least two small bottles of wine, three Black Label whiskies and port on the plane.
When the crew and passengers tried to restrain him he allegedly threatened to kill them and shouted: "You are a fucking wanker, you're fucking dead. Do you know who I am? I'm the head of the British government in Thailand and you're treating me like this."
In his defence, Col Roberts said he began suffering from depression after the death of close friends in the Chinook helicopter crash on the Mull of Kintyre in 1994. Nine days before the flight on February 17 2005, he began suffering vivid "daymares" and his doctor had upped his dosage of Seroxat. But Col Roberts said he miscalculated the dose. He blacked out as the flight passed over Vienna and remembered nothing until he came to in a police cell.
He said he been "shocked and amazed" when police described his behaviour. "It was extraordinarily disgraceful and must have been hugely upsetting to passengers. I can't offer any explanation for this at all, I'm absolutely shocked, I honestly don't remember any of that at all."
He said he had since learned that Seroxat could result in a "hyper-manic state" and was no longer taking it.
After hearing that Col Roberts had suffered adverse effects when mixing alcohol with antidepressants on a previous occasion, Judge Usha Karu rejected a defence application for costs.
The judge said the diplomat had "brought the matter on himself".