The plane approached I-285 from the south, flying so low that Blake Green thought the pilot might be practicing an aerial stunt.

Then the single-engine Piper banked suddenly, flew right over Green’s truck and disintegrated into the median wall of the Perimeter Highway. The four people aboard the aircraft died in that instant on Friday morning, and traffic on one of Atlanta’s busiest expressways backed up for miles in both directions.

Green said the huge blast and the gout of flame and the thick black smoke made it clear there were no survivors.

“I wish there was something we could have done to be able to get them out of there,” Green said. “But just as soon as they hit, there was nothing anybody could do. It sounded like a bomb going off. Black smoke went everywhere. A propeller shot off. It was bad.”

The Piper PA-32 six-seater aircraft had just topped off its fuel tank before taking off from DeKalb-Peachtree Airport around 10 a.m., authorities said.

Greg Byrd, his sons Phillip and Christopher, and Christopher’s fiancée Jackie Kulzer, were on their way from Asheville, N.C., to Oxford, Miss., for a graduation celebration at the University of Missisippi for Byrd’s youngest son, Robert. They had stopped in Atlanta to pick up Christoper and Jackie.

The crash prompted authorities to shut down the outer loop of the Perimeter at the crash site for three hours. The inner loop was closed for five hours.

Don McGhee was driving down Peachtree Industrial, preparing to turn onto I-285, when he saw the plane go down.

“As I’m looking at the plane, the plane is trying to pull up, pull up, pull up and BOOM!” McGhee said. “I heard that loud sound, and I knew instantly it was tragic.”

McGhee got onto I-285, stopped and ran to see if he could help.

“But it was gone by then,” McGhee said. “It was done.”

Bunny Lenhard was on her way to get a manicure when she suddenly saw the belly of an airplane overhead, almost on top of her.

“I looked up and ducked,” said the Sandy Springs woman. In her rear-view mirror a moment later, she saw the plane crash and burn.

She didn’t know how close the plane came to hitting her, but she figures she had to be one of the last vehicles the aircraft cleared before it smashed into the freeway.

“Everybody says this, but it really does feel very surreal … to the point of … did I really see that?” Lenhard said.

‘Nowhere else they could have gone’

Greg Feith, a former senior investigator with NTSB, said a roadway often offers the best chance a pilot has of making an emergency landing. That’s particularly true given that DeKalb-Peachtree is a small airport in a heavily populated area.

Private pilot Robert Young has flown in and out of DeKalb-Peachtree for years, and while he gives high marks to the airport and its staff, he said taking off from the private field is “sort of scary.”

“When you fly out of other smaller airports there’s all kinds of empty space around you,” said Young, a hobbyist who pilots a four-seater Cessna 172. “When you fly out of PDK you’re looking at buildings, traffic, the roof of a Walmart. You have to go outside the Perimeter before you find anyplace to put a plane down.”

Judging from the location of the airstrip and crash site, his assessment was that that plane lost power almost immediately and gave the pilot little time and few options.

“There’s nowhere else they could have gone,” Young said. “It looks like they went straight into that wall. It’s pretty much a straight line off the runway. Where else do you put it?”

The wreckage was taken to Atlanta Air Salvage, a storage facility in Griffin, to be reconstructed. That might take two weeks, with a public report coming in six months to a year.

Among a laundry list of items on its to-do list, the NTSB will be looking at the pilot’s experience and whether the aircraft was maintained properly.

‘It’s a miracle no cars were hit’

Each day, about 200,000 vehicles travel the top end of I-285.

“It’s literally a miracle that no other cars were hit or severely impacted,” said DeKalb County fire Capt. Eric Jackson.

Initially there were reports that drivers were turning around and traveling in the opposite direction on the interstate to reach an exit. Droves of vehicles were diverted onto the metro Atlanta region’s already overtaxed arterial road system.

At the peak of the closure, there were miles-long backups on the north and east sides of I-285, on the Downtown Connector I-75/85 in both directions, on I-85 southbound in from Gwinnett, and on GA. 400 around Sandy Springs.

As accidents go, it doesn’t get much worse or more complicated.

“This isn’t the first plane on a freeway crash we’ve had, we’ve had a number of them,” said Mark Arum, a member of WSB Radio’s Triple Team Traffic since 1997. “But this was by far the most severe. I’ve never seen a plane crash on the interstate that was this bad and had this much of an impact on traffic.”

The crash happened just after peak morning traffic had started to melt away. And all lanes of I-285 were reopened by 3:30 p.m. before evening rush hour commenced.

‘As methodically and carefully as possible’

As tragic and confused as the scene was, the fact that a plane was involved complicated the official response even more. In addition to the usual responses from local and state police, the medical examiner and the state Department of Transportation, investigators from the National Transportation Safety Board had to process the scene as well.

As is their procedure, the federal investigators embarked on a painstaking examination, documenting the position and condition of major components of the plane and determining which parts were missing or damaged. The process took hours, although it could have taken many hours more.

It’s the same process that takes place in a normal plane crash investigation, said NTSB spokesman Keith Holloway. Given that the crash was on the highway, however, the investigator has to work “as methodically and carefully as possible, but also as expeditiously, so it can be removed,” he said. “It’s the same as if it happened on a runway.”

The plane was too small to be equipped with a “black box,” but officials said they should still be able to figure out exactly what happened.

Doraville detained a truck driver whose vehicle was likely clipped by the plane just before it crashed. Police discovered that the man had an outstanding warrant for failure to appear in court from Douglas County on a charge of driving on a suspended license. He is being held at the Doraville city jail until Douglas county picks him up.

“This is pretty much being at the wrong place at the wrong time,” Callaway said. “His license is still suspended and he did receive a citation.”

* Staff writers Russell Grantham, Jennifer Brett, Steve Visser, David Markiewicz, John Spink and Eric Stirgus contributed to this story.