Latvian authorities are searching for a rogue drone that went missing mid-flight - causing air traffic problems.
The country's aviation authority has restricted flights below 19,500 feet in the region while they hunt for it.
While officials say it is likely the 26kg (57lb) drone has landed, it had been fuelled for nearly four days of flight.
The public is urged to call a search and rescue centre if they see or hear it.
The non-military drone is understood to belong to a local unmanned aerial vehicle (UAV) manufacturer.
During a test flight, the firm lost communications with the drone and lost track of its location, Latvian media reports.
It is about 3.5 metres long and 5.5 metres wide (11.5 feet by 18 feet) and has an airspeed of up to 70km/h (43mph).
It was last seen flying at about 200 metres (650 ft). The transport ministry and military were alerted, and a hunt for the drone began, while the aviation authority issued a warning.
The drone took off on Saturday, but was fully fuelled for 90 hours - or 3.75 days - of flight.
Assuming it is still airborne, that fuel is scheduled to run out at 19:10 local time on Tuesday (17:10 BST).
On Monday evening, the aviation authority said that the possibility the drone was no longer in the air was becoming increasingly likely, but that multiple planes were still searching.
Numerous members of the public have reported sightings - but none have been confirmed. There have also been no reports of any UFOs (unidentified flying objects) from neighbouring airspace.
Despite lower air traffic across Europe due to the coronavirus pandemic, the errant UAV has caused some problems, closing airspace over Riga International Airport and forcing the redirection of a flight from China to Tallinn.