While conspiracy theories fill the void, the Northeast Philly crash has left aviation experts baffled

As Med Jets 056 taxied for takeoff, the red-and-white symbol of the Rod of Asclepius painted on its tail fin marked the aircraft’s purpose: lifesaving.

The sleek and swift Learjet 55 — operated by the Mexican air ambulance service Jet Rescue — was topped off with fuel, assigned a runway at Northeast Philadelphia Airport, and cleared to go airborne. It was taking a sick child and her mother back home to Mexico, after a stop in Springfield, Mo.

But what went wrong last Friday night to turn the heavily used jet into a deadly rocket less than a minute after takeoff is a mystery that has left experts puzzled.

As it slammed into a Philadelphia sidewalk at more than 278 mph, dashcams, cell phones, and doorbell cameras captured its fiery explosion. Footage of the crash and the mayhem it created immediately went viral on social media, leading to wild speculation and conspiracy theories — spread with the help of phony videos and even AI-generated air traffic control recordings.

Terrorism. Sabotage. Worse.

“This is screaming ‘cartel hit’ to me.”

“It looks like a missile hit it”

“It has something to do with undetectable sophisticated signal jamming”

The baffling circumstances surrounding the crash itself didn’t help.

Among those who know the conditions that actually could trigger a fatal Learjet crash is Domingo Olivares, 49, a former commercial airline pilot who has logged over 6,800 hours in command of a Learjet 55.

That’s the same model as the crashed jet, which killed all six people onboard and a person on the ground, and injured two dozen more in homes and cars around Roosevelt Mall.

Olivares has experienced bird strikes and trained for other dangerous scenarios, including lost engines and stuck flaps. The jet’s sudden loss of control less than a minute after takeoff puzzles him.

“It’s pretty strange,” Olivares said. “They were talking normal to the tower when they switched to takeoff … then nothing.”

A Learjet 55 is an older model relied on for its lower cost and ability to fly long distances high and fast. It is always flown with a pilot and copilot with identical controls. Its flight systems are more manual than those of many modern jets, which rely increasingly on computers and electronic “fly-by-wire” controls.

Normally, about 400 feet off the ground, the landing gear would be retracted. Between 700 and 1,000 feet, the jet’s twin engines should have created enough speed to bring in the flaps, which produce more lift for takeoff. By around 1,000 feet, the pilots would have engaged autopilot, Olivares said, and, by 1,500 feet, radioed for instructions to safely leave the area.

“Runway 2-4 clear for takeoff. Medevac Med Service 0-5-6 contact Philly Departure 123.8,” said an air traffic controller to the pilots, using their call sign to instruct them to change radio frequency to the regional tower at Philadelphia International Airport, which is responsible for all flights moving in and out of the region.

Calmly, the pilot responded, “One two three point eight. … 056 Medevac, thank you, good day.”

» READ MORE: How the plane crash in Northeast Philly unfolded

Some Learjet pilots preprogram the channel so that with a press of a button on the yoke they are communicating on the new frequency. That communication didn’t happen.

The plane transmitted data automatically at 1,350 feet while it was traveling at 187 knots, or 215 mph, and still climbing. At that point, Olivares said, the jet would no longer be in takeoff mode; the pilots would be focused on cruising at higher speeds.

But, clearly, something was terribly wrong.

Olivares has flown similar aircraft in and out of that airport. It’s relatively straightforward on takeoff: Throttle up, reach altitude, engage autopilot.

“It’s not difficult,” he said. “I don’t understand what happened.”

Among the rumors that filled the void as the National Transportation Safety Board began investigating the crash was that pilot Alan Montoya Perales, 46, and copilot Josue de Jesus Juarez Juarez, 43, were not licensed to fly a Learjet in the United States, because they lacked flight certifications from the Federal Aviation Administration.

“The pilots were qualified to fly the LJ-55,” says Jet Rescue spokesperson Shai Gold. “All relevant documentation to that effect was provided to the NTSB.” Gold said Montoya Perales had 8,700 hours of relevant flight experience, and his copilot had 2,600 hours.

Although the Learjet 55 they flew had a lengthy history, with nine owners since its construction in 1982, that is not unusual for private jets.

Gold said the plane’s previous flight from Miami to Philadelphia was “uneventful.”

“There was no indication of mechanical problems or otherwise system issues,” he said. “If there would have been an issue, it wouldn’t have flown.”

Factors common in other air crashes seem unlikely.

The dark skies above the airport at 6 p.m. Friday were wet and roiling with cloud cover. Within a few hours of the crash, a pilot at Philadelphia International and an airfield in Millville, N.J., reported turbulent conditions to the federal Aviation Weather Center’s database.

But while two other pilots at Northeast Philadelphia Airport reported overcast conditions and a cloud ceiling as low as 500 feet a few hours before the crash, neither reported severe turbulence. No weather records identified any nearby lightning.

Olivares said another common hazard, a bird strike, was rare in a night flight.

» READ MORE: In the Northeast Philly neighborhood where a plane went down, ‘nothing ... will ever be normal again’

What has puzzled many observers is the jet’s steep angle of descent from a relatively low altitude. The high speed coming down suggests that the engines were intact and still providing thrust, while the near-45-degree angle suggests the pilots either did not or could not pull out of a dangerous nosedive.

A stuck stabilizer on the tail, Olivares said, could have forced the nose down. But he would have expected the pilots to slow the plane.

“If you have that problem, with the nose down, you have to reduce the speed and reduce the speed by hand,” Olivares said of how pilots must pull back the yokes to correct a Learjet’s dive. “This is cable control. You have to use force.”

Jeff Guzzetti, a former NTSB investigator, said that pilots train endlessly to avoid this exact scenario during a bird strike or a more catastrophic failure, such as total engine loss.

“This did not have the earmarks of someone making an emergency landing,” said Guzzetti, who runs an aviation consultancy. “There was still engine power.”

Sixteen seconds after the plane transmitted its location, it sent out another reading: climbing to 1,650 feet and 218 knots (251 mph). But its heading veered slightly right before arcing back to the left, as it quickly lost altitude and gained speed.

“Maybe … maybe, it’s a thrust reverse,” Olivares wondered.

Jet engines are capable of switching the direction of their thrust to help slow planes during landings. If one engine were to spontaneously reverse thrust during a takeoff, especially lower to the ground, it could send the plane veering in one direction.

In 1991, a Boeing 767 broke up shortly after takeoff when a thrust reverser inadvertently engaged, leading to the deaths of all 223 people aboard. The Lauda Air crash remains the worst air disaster in Thai history.

But if that was the problem, the Learjet has a way to disconnect an engine’s reversed power, Olivares said, although in the Philadelphia crash, “you don’t have too much time because you’re too close to the ground.”

Other mishaps, like a jammed flap, can have similar effects in the right conditions. But Guzzetti added that such spontaneous mechanical faults were extremely rare.

“Even those systems are pretty bulletproof,” he said. “And then you have to ask why it would happen. Was it inadequate maintenance? Was it inadequate training? Was it a design flaw?”

The former NTSB investigator wondered if the low visibility that night, made more hazardous by overcast and lightly choppy weather conditions, could have exacerbated a phenomenon called somatogravic illusion.

That’s when rapid acceleration or deceleration, or other changes in gravity, can cause pilots to falsely believe a plane is pitching up or down when it is not.

“When you look at those four things — the low cloud ceiling, nighttime conditions, high velocity descent, less than a minute after takeoff — that could be consistent with spatial disorientation,” he said. “That’s the aviation term for how a pilot can lose their sense of right side up.”

Add in other distractions, like changing radio frequencies, and even experienced pilots have lost their bearings while relying solely on their instruments to navigate, Guzzetti said.

In 2015, Flydubai Flight 981 was in a holding pattern around a Russian airport in moderately stormy conditions at night when it also started descending at 45 degrees and slammed into a runway, killing all 66 people aboard. Pilot error was partly blamed; the pilots lost bearing and reacted too strongly to wind shear.

But, like other experts, Olivares and Guzzetti will wait for the NTSB’s findings to learn what actually happened the night of Jan. 31.

Both said it falls to investigators to pore over every recovered section of the obliterated plane, its engines, its maintenance records, and the cockpit voice recorder recovered eight feet deep in the hole where the jet cratered.

“The voice recorder,” Olivares said, “that’s the key to understanding what happened.”

Staff Writer Rodrigo Torrejón contributed to this article.