Identified as Louis Pedro Verdasca dos Santos Costa, the 38-year-old man is said to have locked himself inside the cockpit of the aircraft and refused to open the door which is bullet and explosive proof.
Speaking to Sky News an unnamed source described the incident as “a very difficult and complex situation” and said “in the end the fire brigade had to be called to the plane and carried out a long and very protracted operation to get into the cockpit from outside.
“Eventually, they managed to gain access to the cockpit and police were able to storm in and arrested the intruder.”
The source said it was a “terrifying situation”, adding: “Here is a man who not only has managed to go air-side at one of the world’s busiest airports but he has successfully got to a Boeing 747 jet liner and found it open and was able to climb aboard.
“Then he has got onto the flight deck and barricaded himself in using the plane’s own anti-terrorist equipment.”
Authorities confirmed the incident but did not class it as an act of terror.
Police confirmed there was an incident at Heathrow on a stationary aircraft, and said it is not believed to be terror-related.
British Airways said it had no comment to make on the incident “as a man has been charged and will be appearing in court.”
A statement issued by Heathrow Airport said: “Safety and security are always our main priority and we take incidents involving either very seriously indeed.
“Individuals illegally entering the air-side environment potentially endanger their own lives and those of others. We are working with the police following an incident on Saturday.
“We keep security under constant review.”
The Portuguese man, who according to the British press lives on Stonehill Road in Hounslow, East London, was charged on Saturday, 5 March with offences including unlawfully being airside, and unlawfully being on an aircraft.
He was remanded in police custody and due to appear in court, at the earliest, during the course of this week.