As basketball fans around the world remember Kobe Bryant’s life and grapple with his death, investigations are still underway to determine what caused his helicopter to crash in Calabasas, California.

Recent developments revealed that the pilot who manned the NBA legend’s helicopter was allowed to fly under foggy conditions on Sunday morning. Spokesman Josh Rubenstein told CNN that visibility was so low around the area that the Los Angeles Police Department had grounded its helicopters.

The Sikorsky S-76B helicopter crashed into a rough hillside. None of the nine people on board the chopper survived — including Bryant’s teenage daughter Gianna. As of this writing, the cause of the crash has not been confirmed.

In the audio recording obtained by CNN, an exchange between the pilot and the controller was heard. “Maintain special VFR at or below 2,500,” the pilot said to the controller.

Later on during the flight, the pilot asked for a “flight following” service which indicates regular contact between controllers and an aircraft.

The controller in charge told the pilot “2 echo X-ray, you’re still too low level for flight following at this time.” This meant that the chopper was flying too low to be detected on air traffic control radar.

Conditions have also made it difficult for investigators to determine the cause of the crash. Los Angeles County Sheriff Alex Villanueva told reporters, “It’s a logistical nightmare in a sense because the crash site itself is not easily accessible.”

Retrieval operations to recover bodies from the crash site could possibly take days according to officials.