@Hawkeye, the helicopter only has to be parked in a private location and Assange driven to it under immunity as apparently cars do have immunity (He would need to be smuggled into a car, perhaps in diplomatic luggage) . A helicopter only has to fly for 12 miles off the coast into international waters and drop him off into a boat. Helicopter can return to land.
Potential routes as listed by an article.
"Could Ecuador give Assange a diplomatic passport?
Such passports are supposed to facilitate travel but do not confer immunity from the laws of other states.
Could Ecuador grant Assange diplomatic status?
This would be a bold move by Ecuador, and would ratchet up the crisis. Article 29 of the Vienna Convention states that those with diplomatic status are immune from prosecution. It reads: "The person of a diplomatic agent shall be inviolable. He shall not be liable to any form of arrest or detention. The receiving state shall treat him with due respect and shall take all appropriate steps to prevent any attack on his person, freedom or dignity."
But there is a countervailing obligation on Ecuador to respect the laws of the UK and not to interfere in Britain's internal affairs.
Joanne Foakes, a former Foreign Office lawyer now based at the international think tank Chatham House, said: "In principle, a state can freely appoint anyone as a member of its mission, apart from its head of mission. But if they were to seek to do so now, it would be an obvious device to evade the laws of the receiving state, the UK. In these circumstances the UK may feel justified in repudiating such an appointment."
Could embassy officials put Assange in a diplomatic vehicle and drive him to the airport?
Diplomatic vehicles are immune from searches from the receiving country, in this case the UK. But even if Assange managed to get into an embassy car without being arrested, he would at some stage have to get out to board a plane. At that point he will have lost the protection conferred by being technically on Ecuadorean soil, and would be back under UK jurisdiction and liable for arrest.
Could he be smuggled out – or placed in a crate or bag that has diplomatic protection?
As far-fetched as this sounds, it has been tried before in the UK.
In 1984 an attempt was made to abduct a Nigerian politician, Umaru Dikko, from Britain by placing him in a crate and attempting to ship him back to Nigeria. Those involved tried, but failed, to label the crate correctly as a diplomatic package or bag.
The Vienna Convention says: "The diplomatic bag shall not be opened or detained."
But such a package is not immune from scanning, or from thermal imaging, which would pick up body heat from inside any such package. In such circumstances, UK authorities may be entitled to open the package and seize the concealed Assange."