Three Americans tried to smuggle more than £1.7m of cannabis into Britain in their luggage.
The trio flew from Los Angeles to Heathrow Airport with the drugs last month, Isleworth Crown Court heard last week.
Barrington Walters, 24, from Los Angeles, California, and Mandy Silowka, 34, from Princeton, New Jersey, were caught with a total of almost 60kg of marijuana after landing at Heathrow from LAX on the same United Airlines flight on 17 January.
Border Force officers found 33kg of herbal cannabis in bags belonging to Walters and another 26.5kg in suitcases checked in by Silowka when they landed in the UK.
Another US national, Kiara Lanee Malone, 31, from St Louis, Missouri, was arrested after arriving at Heathrow from Los Angeles on 10 January, when 27.5kg of cannabis was found in her luggage.
National Crime Agency (NCA) investigators estimate the total amount of all the cannabis found in their luggage had a combined street value of more than £1.7m.
All three were found guilty of importing class B drugs.
Walter was jailed for 10 months and Silowka for a year after they were sentenced at Isleworth Crown Court last Thursday. Both had pleaded guilty at an earlier hearing.
On Friday, Malone pleaded guilty at the same court and was remanded in custody to be sentenced on 5 April.
She claimed she travelled to the UK to have cosmetic procedures and said she was given the bags by someone else and believed they only had clothes inside.
The convictions follow a string of recent arrests involving seizures made from flights from the US. Cannabis grown legally in parts of the US can attract a much higher price in the UK when sold to criminal gangs.
Andy Noyes, NCA Heathrow branch commander, said: "These cases serve as further warnings to those who think they can get away with smuggling drugs into the UK.
"No matter what you might get told by those organising these trips, you will get caught, and as these individuals will tell you, you will face jail time."
Another US national, Isabella Carrasco, 20, was arrested on Wednesday following a large cannabis seizure at Edinburgh Airport after she arrived on a flight from Los Angeles, via London.
Carrasco has been charged and will appear before Edinburgh Sheriff Court next week.
Her case is being investigated by the Organised Crime Partnership in Scotland, a joint team of NCA and Police Scotland officers.