A pilot suspected of people smuggling was arrested after a police air chase.
The six-seater plane was seized pending further inquiries
A Piper Cherokee six-seater dropped off nine suspected illegal immigrants from Turkey in two landings at Lamberhurst airstrip, Kent, on Friday morning.
Police swooped after the second landing but the plane took off. A police helicopter pursued it to an airstrip 10 miles away, where a man was arrested.
Eighteen people, including passengers and others who met them at the airstrip, are being held by police.
The plane is suspected of flying illegal immigrants into the UK from Belgium and France.
Officers said the plane first landed at Lamberhurst just before 0800 BST, and four people and a child were collected by a man who drove them to a restaurant in north London.
There the group was met by another man - all six adults were later arrested, a police spokesman said.
Police said the pilot then flew across the Channel from Lamberhurst to collect four more people, who he returned with at about 0945 BST.
Police arrested the passengers and two more drivers, but the pilot took off immediately.
The Piper PA-32-300 Cherokee was chased by helicopter to Headcorn airstrip, where a man was arrested and the plane seized.
Another five people were arrested at the restaurant during the day and £13,000 was retrieved, police added.
Detective Chief Inspector Alex Wood of the National Crime Squad said: "The route and method used differs from the norm and illustrates the resourcefulness of people smugglers."
Mr Wood said he believed the plane had carried out 10 trips of this kind and the pilot was paid £4,000 each time.
The passengers are thought to have each paid 10,000 euros (£7,100) for the whole journey from Turkey to the UK, he added.
Lord Brett, of the International Labour Organisation, told BBC London: "We are talking about people coming from Europe, which is a relatively short hop in terms of light aircraft and there are many, many airfields in Kent and Sussex which they can fly to.
"The fact it has been discovered now will probably act as a chastener for a little time, but unless the root causes of the problem are dealt with we will always find people prepared to make profit out of the misery of other people."