And once flames erupted, did everything go as it should to safely get the 101 people off the plane?
Those are among the major questions Friday, one day after a fuel leak reported on Dynamic International Airways Flight 405 was followed by flames, billowing black smoke and a rush to evacuate. What was supposed to be a trip to Caracas, Venezuela, very quickly and alarmingly turned into doing whatever it took to get safely onto the South Florida airport's tarmac.
Twenty-one people, including a child and trauma patient, were taken to Fort Lauderdale's Broward Health Medical Center after the incident, Broward County Sheriff's Office spokesman Mike Jachles tweeted. Two of them were still there Friday morning in stable condition, hospital spokeswoman Amy Erez told CNN.
Thankfully, there have been no deaths, though Mary Schiavo, a CNN aviation analyst and former inspector general for the U.S. Department of Transportation, said it could have been a lot worse.
"Had they reached a speed of 160 mph ... on that runway, they would have had to lifted off," she told CNN's "New Day," lauding the pilot of a plane behind Flight 405 who alerted air traffic control to the leak. "And they would have been a danger to not only ... everyone on the plane (who) could have been lost, but the people over whose heads they were flying.
"This was a few seconds away from a disaster."
Still, the episode was calamitous enough. But did it have to have been?
Analyst: Problems with evacuation
That's the task facing a four-person National Transportation Safety Board team that's been dispatched to look into the fire, the agency tweeted. By Friday morning, those investigators were meeting with airport officials and Dynamic International Airways representatives, Fort Lauderdale airport spokesman Greg Meyer said.
The NTSB team will look at maintenance records, talk with crew and passengers who were on the aircraft, review the contents of "black boxes" and do other digging to try to get to the bottom of what happened, said Kent George, the airport's director.
"They are very, very thorough in what they look at," George said. "And they look at the entire operating system of the entire aircraft."
One focus will be pinpointing the source of the leak, including how it got there and who might have had a role in it.
"I think the NTSB is going to be looking at maintenance on this one, and where it last was, and who last touched it in the maintenance shop," Schiavo said Friday.
Then there is what part the Dynamic crew played. As Schiavo pointed out, one of the first things you're taught in flight school is to walk around a plane and check for "obvious leaks." Assuming this happened and nothing was found, then what happened?
"It could have been a scenario where the engine disintegrated, and that caused the shrapnel to come out of it and the fuel line to be cut, and that would ... cause the fire," CNN aviation analyst Miles O'Brien said Friday morning. "Or the fuel line problem initially (could have) caused the fire."
After reviewing video from the incident, O'Brien also questioned the evacuation process.
"No. 1, the forward left slide was deployed. That ... shouldn't be the procedure (because) that's the side where the fire is," he said. "You don't want people evacuating into that acrid smoke and near the fire."
O'Brien further pointed out that the door over the right wing was opened but that an emergency slide there didn't deploy, as it should have.
Airlines, regulators have responsibility
Then there are questions about Dynamic International Airways.
On its website, the airline said
"the actions of the cabin crew were exemplary and according to their safety training." Still, no initial explanation was given for the fire beyond "flight crew as well as airport personnel noticed engine problem during taxiing and acted according to emergency procedures."
According to an FAA database, the plane that caught fire was built in 1986.
The Greensboro, North Carolina-based Dynamic -- which serves New York, Fort Lauderdale, Venezuela and Guyana, according to its website -- is much younger than that. And it's had issues before, including reportedly filing for bankruptcy this summer.
"An airline in financial trouble is supposed to be put under a special watch," Schiavo said. "... The FAA has to watch these kinds of airlines closely, but it doesn't appear that they were."
Whether or not that's the case, O'Brien noted that government agencies can do only so much, especially with so many airplanes flying in and out of the United States, many of which had undergone maintenance in other countries.
"They have to rely on the airlines to essentially do the right thing. It's a partnership," he said. "And frankly, they don't have the resources to be there looking over their shoulder every step of the way."
Passenger: 'I was terrified'
As the investigation continues, the Fort Lauderdale airport, which had 219 flights delayed and 43 canceled because of the incident, appeared to be back to normal Friday. But memories of what happened around 12:30 p.m. the previous day lingered.
Audio from the air traffic control tower caught one of the pilots saying, "The left engine looks like it's leaking a lot of fuel. There is fluid leaking out of the left engine."
Less than 30 seconds later, as the tower was contacting the ramp so the Dynamic jet could return, a pilot said, "Engine's on fire. Engine's on fire."
The first sign of trouble for Dynamic passenger Andres Gallegos was "a loud bang."
"I ... turned around, saw lights and flames (and) ran to the front of the aircraft," he told reporters.
Daniela Magro admits she started "freaking out," though she wasn't alone.
"I was terrified about what was going on," she said. "I had people in front of me, and I started pushing."
Thankfully, none of the flames got into the plane's main cabin, said George, the Fort Lauderdale airport's director. But up to 50 gallons of jet fuel did leak onto the taxiway, damaging asphalt that should be fixed by early Saturday, he said.
Operations should not be significantly affected going forward, George said, crediting the minimal disruption and the fact casualties weren't worse the "phenomenal" efforts of first responders.
"You saw within 4 minutes the response and complete knockdown of the fire," George said. "Operation-wise and safety-wise, it couldn't have worked any better."