"Be advised there's something on final [descent] here we don't, we thought maybe it was a drone, uh, but there's, uh, definitely, uh, something on final here," a pilot for Southwest Airlines approaching Newark airport told air traffic control on Tuesday night.

When the air traffic controller asked, "And you say something on final, I'm not sure what you mean. Like an object or something?" the pilot responded, "Yes sir, an object and it definitely looks like a drone. It was pretty close. I'd say within, uh, I would say, a quarter mile at most off our right."

The sighting, coupled with another pilot's report, prompted the Federal Aviation Administration to call a brief stoppage on all arriving flights at Newark Liberty International Airport. But a spokesperson for the world's biggest drone manufacturer was "deeply skeptical" that the pilots actually saw a drone.

"At approximately 5 p.m. Tuesday, we received two reports from incoming flights into Newark that a drone was sighted at about 3,500 feet above Teterboro, New Jersey," an FAA spokesperson told Gothamist. "At that point, flights arriving into Newark were held for a short duration. With no further drone sightings, arrivals resumed."

Adam Lisberg, the spokesman for DJI, which currently has about 74% of the drone market, counters that it's "highly unlikely that someone could fly a drone at 3,500 feet in altitude... outside on a below freezing day."

Lisberg also doubts whether two separate pilots—one for Southwest Flight 476 and the other for United Flight 2335, who said the drone was 30 feet off the right wing—could have actually seen a drone while flying at extremely fast speeds. "A drone, it could be the size of a dinner plate or even smaller than that," he told ABC 7. "If I were driving at 150 miles an hour, I don't think I could spot something the size of a drone sitting by the side of the road. I think it's even harder to do that in an airplane."

While there have been incidents where drones have collided with aircraft—in December 2017, a Staten Island man's drone collided into a Black Hawk helicopter at just under 300 feet—Lisberg said, "It's far more likely it was a balloon or a bat or a plastic bag—all of which have been mistaken for drones in the past."

The drone spokesman also cited a study that found pilots are unable to accurately determine the distance between the aircraft and drones, claiming drones were actually much closer than they really were. "This is not a knock on the pilots," Lisberg said. "It’s past the limits of human perception."

Last month, Gatwick Airport near London, England, cancelled about 1,000 flights over three days before the Christmas holiday because of alleged drone sightings; the mystery is still ongoing and investigators are offering a 50,000-pound reward for information leading to an arrest. During the Newark drone panic—one passenger said his pilot said they were circling because of "drone activity" and other flights' pilots commented they were low on fuel—Lisberg touted DJI's AeroScope technology that can locate all DJI drones within range, as well as the drones' pilots. DJI does work with some airports on drone-spotting, but the most high-profile instance of AeroScope being used to find rogue drones has been at the Albuquerque Balloon Fiesta last October—450 drones illegally crossed into balloon-only, restricted airspace.

There are mounting concerns about the threat posed by drones to airplane traffic (aside from homeland security worries or the possibility that one will fall from the sky, hit someone poolside, and explode into flames). John Halinski, former deputy administrator of the federal Transportation Security Administration, told the NY Times, "This is a really disturbing trend. It is a real problem because drones are multiplying every day. They really pose a threat in a number of ways to civil aviation."

The Port Authority, which oversees Newark, JFK and LaGuardia Airports, said in a statement provided to the Times that "the presence of drone activity near major airports is a serious threat to public safety and can cause significant disruption to flight operations, impacting thousands of passengers." However, the agency did not disclose its approach to handling drones. The Times added, "Last week, the Port Authority said it held a meeting with local, state and federal agencies 'to review and enhance protocols for the rapid detection and interdiction of drones.'"

Drone enthusiast and Gothamist co-founder Jake Dobkin, who recently passed his FAA licensing exam for unmanned aircraft systems, agrees it would be very difficult to operate a drone at 3,500 feet. "Most consumer drones have altitude limits built into the controller apps—for instance, the default on DJI's app is 360 feet above ground level," he said. "You can override it to fly up to about 1,600 feet, but there's no way to go higher than that, at least not without hacking the system."

Further, there are practical challenges. "A drone can rise about 10 feet per second, so to get up to say 3,500 feet, you're talking about flying straight up for six minutes," estimated Dobkin. "Then good luck trying to control the drone—it's very likely you'd lose the radio connection, especially in congested signal areas like the NYC area. Even if you maintained it, you'd be fighting really high winds and cold temperatures, both probably well outside the safe operating limits of a consumer drone." (In November, wind caused a drone to hit the side of a midtown office building, leading to the arrest of its pilot.)

"Now, of course there are professional drones that can fly higher and longer than consumer drones, but they're very expensive, and the pilots who fly them are generally licensed with the FAA and not nearly stupid enough to risk their $15,000 drone, loss of license, and massive fine by flying into Class B airspace without permission," Dobkin opined.

The FAA spokesperson said that small drones would not be detectable on radar. "Individuals who operate drones unsafely can face fines from the FAA of up to $1,437 per violation, while businesses that fly unsafely can face fines of up to $32,666 per violation," the spokesperson described. "On top of that, people who fly drones unsafely can face federal criminal penalties including fines of up to $250,000 and/or imprisonment for up to three years."

Boeing has been experimenting with lasers to fight drones, as has China. Also, the Netherlands has trained eagles (!) to attack illegal drones:

So what was it that shut down Newark airport Tuesday night if it was not a drone? That remains a mystery, along with the mystery of just what exactly those other pilots spotted at 40,000 feet over the Arizona desert .