Ukraine’s air force spokesman Yuri Ihnat told Ukrainian television on Sunday it wasn’t immediately clear how long the probe would take.
According to the air force’s Telegram page, two L-39 training military aircraft collided on Friday during a combat mission over Ukraine's western Zhytomyr region.
Three pilots were killed, including Andriy Pilshchykov, a well-known pilot with the nickname “Juice” who was an outspoken advocate for Ukraine getting F-16 fighter jets.
President Volodymyr Zelenskyy in his nightly address on Saturday paid tribute to Pilshchykov, describing him as a “Ukrainian officer, one of those who helped our country a lot.”
Ukraine’s Vasilkiv tactical aviation brigade on Sunday identified the other two pilots killed in the collision as Viacheslav Minka and Serhiy Prokazin.
Russian forces, in the meantime, targeted central and northern regions of Ukraine with cruise missiles overnight.Ukraine’s air force on Sunday reported air defences successfully intercepted four of them.
In the Kyiv region surrounding the Ukrainian capital, the falling debris damaged a dozen private homes and wounded two people, Ukraine’s Interior Ministry said.
In Russia, the Defence Ministry reported bringing down two drones over the Bryansk and Kursk regions that border Ukraine.
The drones, the ministry said, were launched by “the Kyiv regime” in “yet another attempt at terrorist attacks” on Russian soil.
Kursk Gov. Roman Starovoit, however, reported that a drone slammed into a multistory residential building in the region's namesake capital.
It wasn’t immediately clear if it crashed after being shot down by air defences, like the Defence Ministry reported, or was targeting the building. Starovoit said no one was hurt, but a number of windows were shattered.
The DBR has opened an investigation that will determine whether the planes were in good condition and whether all rules were followed prior to the flight. Specialists also will examine the so-called black boxes that record data about the planes’ movements and pilot reactions.
"It is too early to discuss details. Certainly, all circumstances will be clarified," President Volodymyr Zelenskiy said in his nightly video address, noting that August 26 is Ukraine's Aviation Day.
Debris from a midair collision between two Ukrainian planes on a training mission over Ukraine's Zhytomyr region on August 25, which left three pilots dead.
Zelenskiy also said one of the pilots killed, Andriy Pilshchikov, who went by the call sign Juice, was a Ukrainian officer "who greatly helped our state."
He expressed condolences to all three pilots' friends and loved ones in a post on X, the social media platform formerly known as Twitter. "The investigation is ongoing, and the truth will be revealed. Ukraine will never forget all those who defended its free sky," he added.
The Ukrainian Air Force said earlier that Pilshchikov, who had become well known after giving numerous interviews to international media in which he called for modern fighter jets to be provided to Ukraine, was one of the pilots killed.
"We express our condolences to the families of the victims. This is a painful and irreparable loss for all of us," the Air Force said on Telegram.
Pilshchikov, a major in the Ukrainian Air Force, "dreamed" about F-16s in the Ukrainian sky, said Yuriy Ihnat, a spokesman for the Ukrainian Air Force.
A tragic loss. On August 25th, two L-39 military jets collided in the sky over the Zhytomyr region. Three pilots of the Ukrainian Air Force lost their lives. One of them was Captain Andrii Pilshchykov, a recipient of the Order of Courage, 3rd Class, known by the callsign 'JUICE'.… pic.twitter.com/Pg95JcfRBc
"Pilshchikov devoted his short but very bright life to combat aviation. He dreamed of F-16s in the Ukrainian sky! And he has done a tremendous job on this issue," said Ihnat on Facebook.
NATO countries Netherlands, Denmark, and Norway plan to send an undisclosed number of F-16 jets to Ukraine. Kyiv has said it needs the planes to bolster its dwindling fleet of Soviet-era jets as it carries on with a counteroffensive in the face of a significant Russian advantage over the skies of Ukraine.