The helicopter pilot flying Kobe Bryant, the basketball star’s daughter and six other passengers Sunday grappled with poor weather, asking at one point for special permission to fly by sight in worse than normal visibility, but he displayed no signs of concern in his communications with air traffic controllers.

Shortly after he got special clearance to continue through controlled airspace, he veered from Highway 101 below and crashed into the Calabasas, Calif., hills. All nine onboard were killed.

On Monday, the investigation got underway, with a team from the National Transportation Safety Board arriving at a crash site guarded against curious eyes by sheriff’s deputies on horseback, as the sports world continued to mourn one of its greats.

The poor weather will be one dimension of the crash investigation — and investigators asked the public to send them photos showing conditions at the time — but the pilot’s record and the helicopter’s maintenance history will also be part of the review.

“We are not just focusing on weather,” NTSB board member Jennifer Homendy said. “We look at man, machine and the environment, and weather is just a small portion of that.”

In air traffic control records reviewed by The Washington Post, the pilot requested permission to fly under the special conditions near Burbank Airport. Homendy said the pilot circled for 12 minutes until the approval came.

On the records reviewed by The Post, the Burbank controller responds that it will be a few moments and asks the pilot to hold. Seconds later, the controller tells the pilot that he can plan to transition to the north side of Van Nuys Airport. He tells the pilot several departures are coming off a runway and to “expect to follow the I-5 north and cross that way.”

“No problem,” the pilot responds, according to audio captured by the website LiveATC.

Ara Zobayan, the pilot at the controls, was experienced at flying in the area and served as Bryant’s pilot for a number of years, according to the director of a Los Angeles aviation trade group. Zobayan had held a commercial license since 2007 and was qualified to fly in bad weather under regulations known as instrument flight rules, according to FAA records. He was also qualified to teach people to fly in those conditions, indicating that he had significant experience.

Nevertheless, Jeff Guzzetti, a former crash investigator for the Federal Aviation Administration, said the weather could have been a factor in the crash and pointed to numerous incidents in which pilots have been caught off guard.

Guzzetti said it appears the weather worsened as the pilot tried to follow special visual flight rules (VFR), which meant he had to fly lower to keep clear of the clouds and be able to see the ground below. He said a question for investigators now will be, “Why did this flight occur when the weather was so poor?”

As investigators began to search the debris field on the hillside and understand the fatal crash, a stunned sports world expressed its grief. There were six NBA games scheduled Monday, but the Lakers had the night off. The team returned to Los Angeles from a road trip Sunday, and officials and players, including superstar LeBron James, looked upset coming off the plane.

“There were lots of tears, disbelief and shock,” said a person who was on the plane, who was not authorized to speak publicly. “Everyone was reading Twitter and hoping the first reports weren’t true.”

Players and team officials have made no public comments — even the team’s official Twitter account had gone dark — but behind the scenes, preparations were underway to honor Bryant, one of the game’s most visible and celebrated stars. The Lakers had been scheduled to host the crosstown Clippers on Tuesday night at Staples Center, where Bryant has two numbers — 8 and 24 — hanging from the rafters. But late Monday, the league said the game was postponed out of respect to the team.

Fans and league officials continued discussions on how best to honor Bryant’s legacy, with some fans rallying around the idea of changing the NBA’s logo to a silhouette of the former Lakers great.

The scope of the tragedy also came into sharper focus Monday as the other victims were identified. The group had been on their way to a basketball tournament where Bryant was to coach the Mambas girls’ basketball team and his daughter, Gianna, 13, was scheduled to play.

Christina Mauser, 38, was one of Bryant’s assistant coaches for the Mambas. John Altobelli, 56, was an accomplished baseball coach at Orange Coast College and was on the flight with his wife, Keri Altobelli, and 13-year-old daughter, Alyssa, a teammate of Gianna. Payton Chester, a 13-year-old from San Juan Capistrano, Calif., was also a basketball player. She was on the flight with her mother, Sarah Chester.

“They were just great people,” Catherine George, Payton’s grandmother, told NBC News. “They had a fortunate life and got to travel and spend time together a lot. Sarah was the heart of that family. She died doing what she loves.”

The group had been heading from John Wayne Airport toward Thousand Oaks.

Flight path data collected by flight-tracking service Flightradar24 shows the helicopter cut across the broad coastal plain of central Los Angeles before going north around the basin of the San Fernando Valley and finally attempting to get across the rising terrain leading to Thousand Oaks.

After the pilot’s request, the tower responded that he should head northwest and “follow the 5 Freeway. Maintain special VFR, special VFR conditions at or below 2500 [feet].”

The pilot repeats back the instructions: “Maintain special VFR at or below 2500 [feet], [follow] I-5 northbound.”

The controller said, “Number2EchoX roger, and you’re cleared . . . ”

The pilot responded: “Copy that. We’ll maintain Special VFR, Copter 2Echox.”

Though the controller gave the clearance, FAA spokesman Ian Gregor said that a pilot remains responsible for determining whether it is safe to fly and for determining visibility.

Stephen Streiker, a flight instructor who lived in Los Angeles for eight years, said the helicopter flew into an area that rises quickly in elevation in about two miles. With low clouds, he said, a pilot would be squeezed into an ever-decreasing pocket of clear airspace.

The preliminary data suggests the helicopter, which crashed about 40 minutes after takeoff, briefly climbed to a top altitude of above 2,500 feet and then descended at a high speed before the crash.

Shortly before the helicopter crashed, the Flightradar24 data shows it veering sharply to the left. John Cox, a veteran aviation safety consultant and crash investigator, said it’s too soon to know why that might have been.

“It’s a matter of being patient and letting the system work,” Cox said.

The NTSB investigative team flew to California on Sunday night, and the board typically releases preliminary findings within a few days. But a final report with conclusions about the causes of a crash could take a year or more.

Homendy said the NTSB was working with the FAA, the manufacturer of the helicopter and its engines, and the company that operated the flight. The helicopter didn’t have a black box and wasn’t required to. The FBI was helping manage the crash site, which Homendy said stretched some 600 feet, with chunks of the helicopter lying along the hillside.

“It was a pretty devastating accident scene,” Homendy said, adding that she expected the team to be on site for about five days.

As the investigation was getting underway, the Los Angeles County Medical Examiner-Coroner Department said it was continuing to recover bodies. Three of the dead were recovered Sunday before it got too dark, the office said.

The helicopter was a Sikorsky S-76B built in 1991. The S-76 is the first model the company developed for commercial use rather than military missions, initially for transporting offshore-oil-rig workers before becoming a popular option for wealthy people.

Experts say the model has a good safety record, although variants have been involved in several high-profile crashes. In 2002, an S-76 went down in the North Sea, killing 11 people. Investigators found a rotor blade failure led to the tragedy, and the FAA issued a safety directive ordering the review and removal of the rotor blades. Three years later, another S-76 went down in Estonia, killing 14 people aboard. After that crash, the NTSB called for greater scrutiny of the helicopter’s main rotor parts and urged the FAA to direct operators to emphasize preflight checks.

Lockheed Martin, which owns the Sikorsky brand, issued a statement saying the company was ready to help with the investigation and would share any “actionable findings” with its customers.

The S-76B carrying Bryant on Sunday was owned by Island Express Holding Corp., according to FAA records.

Chuck Street, director of the Los Angeles Area Helicopter Operators Association, said Island Express’s sister company, Island Express Helicopters, is among a handful of smaller firms that provide helicopter rides in the area, operating a fleet of six aircraft. The vast majority of its business involves carrying passengers out to Catalina Island off the coast south of the city, Street said.

The crash is not the first deadly incident involving the company. One of its helicopters, an Aerospatiale AS-350-D, crashed in 2008, killing the pilot, another company employee and one passenger and injuring three others. The NTSB determined that crash was caused by loss of engine power due to a fatigue fracture of a turbine blade.

And in 1985, the company was involved in another deadly crash, according to a Los Angeles Times report from the time.

Representatives of Island Express could not be reached Monday.

Street said he met with Zobayan regularly, describing him as well-trained and cautious and “more than competent” to navigate the weather in the area Sunday. Bryant had flown with Zobayan “dozens and dozens of times,” Street said.

The death of the pilot, who a former employer said was inspired to learn to fly after riding in a helicopter tour of the Grand Canyon more than two decades ago, has shaken the close-knit community of pilots in Los Angeles. Street said those who knew him are “just devastated.”

Ben Golliver in Los Angeles and Matt Bonesteel in Washington contributed to this report.