A cargo jet that never should have run out of runway did exactly that Sunday, and now federal investigators are zeroing in on a single, critical question: did the plane touch down too far down the strip to ever stop safely in time?

What Investigators Are Examining

Video of Sunday's landing appears to show the Boeing 767 remaining airborne well past the point where it should have touched down, floating deeper into the runway before finally making contact. Aviation experts say investigators will work to pinpoint exactly where the plane landed — and if it touched down beyond the standard landing zone, why the pilots didn't simply abort the attempt and circle back for another try.

A Wide Net of Contributing Factors

Beyond the touchdown point itself, investigators will scrutinize the plane's speed and braking performance, prevailing weather and wind conditions, the aircraft's mechanical condition, and any other factors that might have contributed to the deadly runway overrun. The National Transportation Safety Board has dispatched a team to Miami, led by Chairwoman Jennifer Homendy, who is expected to deliver the agency's first public briefing on the investigation Monday.

How the Crash Unfolded

The aircraft overran the runway around 2 p.m. Sunday after arriving from San Juan, Puerto Rico, barreling across a road commonly used by warehouse workers and nearby businesses surrounding the airport. Five people died in the crash, three suffered critical injuries, and two others were hospitalized with less severe injuries, officials said.

A Scene of Chaos and Smoke

The crash sent thick black smoke pouring into the sky, according to Miami-Dade Fire Rescue Chief Ray Jadallah, who said the pilot and copilot became trapped inside the cockpit while some vehicle occupants were also trapped in their cars. Crews additionally had to extricate a person pinned beneath a vehicle. It wasn't immediately clear whether the pilots were among those killed.

Why the Landing Zone Matters So Much

Aviation experts note that a typical landing zone falls within the first 3,000 feet of a runway. If the cargo jet touched down beyond that window, aviation safety expert Steve Arroyo said, standard protocol should have called for an aborted landing followed by a go-around for a second attempt.

A Troubling Pattern in the Video

Mary Schiavo, a pilot and former Inspector General of the Transportation Department, said footage posted online shows the Amazon-branded plane floating above the runway for an extended stretch without the nose flaring upward — a maneuver typically used to force the main landing gear down onto the pavement.

At the time of the crash, rain wasn't falling, but dark storm clouds loomed overhead and strong winds had been reported. Schiavo suggested that a tail wind could have played a role in pushing the plane further down the runway than intended.

"A tail wind would certainly add to your troubles if you've already given up a good chunk of the runway by not touching down and landing right away," Schiavo said.

A Safety System Miami Didn't Need

Miami International Airport isn't equipped with the arresting systems the FAA has installed at more than 120 airports nationwide, designed specifically to safely stop planes that overrun the end of a runway. Those beds of lightweight, crushable material have been credited by the FAA with helping save at least 497 lives aboard planes that ran off runways elsewhere.

Why Miami Was Exempt

According to Mike O'Donnell, the FAA's former director of airport safety and accident investigations, Miami's airport appears to be in full compliance with federal regulations and wasn't required to install an arresting system, since it maintains a 1,000-foot safety buffer at the end of its runways. That particular safety requirement traces back to American Airlines Flight 1420, which overran a runway at Little Rock National Airport in Arkansas in 1999, killing nine people.

The Aircraft Itself

Images from the scene showed the Prime Air-branded plane coming to rest beside a roadway near two semitrucks, resting on its belly and remaining largely intact despite the fire that followed the crash.

A Well-Traveled Aircraft With a Long History

The flight was operated by 21 Air, a cargo carrier based in North Carolina. The 32-year-old Boeing 767 was originally built to carry passengers and flew for several airlines over more than two decades before being converted into a cargo plane in 2015, according to flight-tracking site Flightradar24.

Schiavo said the NTSB will also closely scrutinize the aircraft's maintenance history — particularly given its past foreign ownership, which reportedly included a Russian company at one point.

Ripple Effects Across Miami's Airport

The crash halted flights at the busy travel hub for much of Sunday afternoon, and disruptions continued to hamper air travel into Monday. Miami International Airport confirmed that two of its four runways remained closed Monday morning, with operations expected to be affected throughout the day, since aircraft and flight crews scheduled to arrive were delayed by Sunday's crash-related cancellations.

Amazon's Response

Amazon issued a statement confirming it would cooperate fully with any investigation into the crash. "We're heartbroken to learn that five people lost their lives in today's incident at Miami International Airport," the company said. "Our deepest sympathies go out to the families, loved ones, and all those affected by this devastating loss."

Echoes of a Previous Cargo Crash

This isn't the first fatal cargo plane crash to draw scrutiny in recent memory. Last year, a UPS plane crashed after losing an engine while accelerating down the runway at Louisville's Muhammad Ali International Airport. That crash killed all three pilots aboard, along with 12 people on the ground, and left 23 others injured.