On Monday morning, a DHL cargo plane crashed as it came in to land at Lithuania’s Vilnius (VNO) airport, killing one person on board and injuring three others.
After departing from Leipzig, Germany, the Boeing 737 made a “forced landing” one kilometre from the airport, splitting into pieces upon impact and sliding more than 100m, leaving a trail of burning wreckage.
Germany’s foreign minister suggested the incident could have been a hybrid attack in “volatile times”, apparently referring to suspected acts of sabotage by Russia against Ukraine’s EU allies.
German authorities are already investigating several fires caused by incendiary devices hidden inside parcels at a warehouse in Leipzig for delivery by DHL earlier this year.
Lithuanian officials said there was no indication of sabotage so far but the probe into the crash continues.
Here, i looks at some of the unanswered questions surrounding the incident.
Was there an emergency transmission from the Boeing crew?
The Boeing 737-400 jet – operated by airline Swiftair on behalf of DHL, a German logistics group – left Leipzig at 2.08am GMT, crashing north of Vilnius airport’s runway at 3.30am.
A surveillance video showed it descending normally as it approached the airport before sunrise, then exploding into a huge ball of fire behind a building.
A Lithuanian police spokesperson said one person onboard, a Spanish citizen, was killed, and three others – Spanish, German and Lithuanian citizens – were injured.
Lithuanian officials said there had been no signs of anything unusual from the pilots during radio contact with the aircraft.
Minutes before the crash, the pilot greeted air traffic controllers on the ground and established the correct runway for landing.
But as the plane made its final approach, comms went silent and attempts to contact the crew were unanswered.
“In the recording of the conversation between the pilots and the tower, the pilots until the very last second did not tell the tower of any extraordinary event,” said Marius Baranauskas, head of the Lithuanian National Aviation Authority on Monday.
“We need to examine the black boxes to know what was happening in the aircraft.”
On Tuesday afternoon, the Lithuanian Justice Ministry said the black boxes, containing flight data and voice recorders, had been found.
Investigators are preparing to examine the material, the government later added in a statement.
Why did the DHL plane flip onto its side on final approach?
In footage of the incident, the plane is seen turning quickly on its side moments before crashing in a residential area, near a road.
The same movement was described by witness Kotryna Ciupailaite, who saw the plane flying over her car as she drove to work.
“The right wing of the plane turned down before it crashed as if it was trying to turn,” she said. “There was something shiny coming out of the right side of the plane, like sparks or a flame, before it hit the ground.”
What is Germany saying about the DHL crash?
The crash comes amid heightened suspicion among Western security officials that Russia is carrying out sabotage against their nations in retaliation for their support for Ukraine.
After expressing sympathy for the victims, German foreign minister Annalena Baerbock said a hybrid attack could not be ruled out.
“We and our Lithuanian partners must now seriously ask ourselves whether this was an accident or, after last week, another hybrid incident,” she said. “That shows what volatile times we are living in in the middle of Europe.
She was apparently referring to damage to two data cables under the Baltic Sea, one of which ends in Germany, which German officials believe was caused by sabotage.
Have there been previous attacks at the DHL warehouse?
German investigators are already looking into several fires caused by incendiary devices hidden inside DHL parcels at a warehouse in Leipzig, a major freight hub.
In August, authorities warned businesses that dangerous parcels might be in circulation, after freight sent by private individuals in several European countries caught fire while in transit.
The head of Germany’s domestic intelligence agency told a parliamentary committee that on one occasion in July, a plane crash had only narrowly been avoided when an air freight parcel caught fire before being loaded on board.
At the same parliamentary hearing, Thomas Haldenwang pointed to a significant increase in Russian espionage and sabotage activities in Germany.
British police are investigating a fire at a DHL warehouse in Birmingham in July caused by a package catching alight, which Polish officials have linked to Russian-backed saboteurs.
Polish authorities have made four arrests concerning the incident after parcels “containing explosives” were allegedly sent via courier companies to the UK and other EU countries.
Prosecutor Katarzyna Calow-Jaszewska said the group’s goal was allegedly “to test the transfer channel for such parcels, which were ultimately to be sent to the United States of America and Canada”.