A mysterious voice is haunting American Airlines’ in-flight announcements and nobody knows how

Here’s a little mystery for you: there are multiple reports of a mysterious voice grunting, moaning, and groaning on American Airlines’ in-flight announcement systems, sometimes lasting the duration of the flight — and nobody knows who’s responsible or how they did it.

Actor/producer Emerson Collins was the first to post video, from his Denver flight on September 6:

Here’s an MP3 of the audio with just the groans, moans, and grunts, with some of the background noise filtered out.

This is the only video evidence so far, but Emerson is one of several people who have experienced this on multiple different American Airlines flights. This thread from JonNYC collected several different reports from airline employees and insiders, on both Airbus A321 and Boeing 737-800 planes.

Other people have reported similar experiences, always on American Airlines, going as far back as July. Every known incident has gone through the greater Los Angeles area (including Santa Ana) or Dallas-Fort Worth. Here are all the incidents I’ve seen so far, in chronological order:

  • July – American Airlines, JFK to LAX. Bradley P. Allen wrote, “My wife and I experienced this during an AA flight in July. To be clear, it was just sounds like the moans and groans of someone in extreme pain. The crew said that it had happened before, and had no explanation. Occurred briefly 3 or 4 times early in the flight, then stopped.” (Additional flight details via the LA Times.)
  • August 5 – American Airlines 117. JFK to LAX. Wendy Wanderman wrote, “It happened on my flight August 5 from JFK to LAX and it was an older A321 that I was on. It was Flight 117. There was flight crew that was on the same plane a couple days earlier and the same thing happened. It was funny and unsettling.”
  • September 6 – American Airlines. Santa Ana, CA to Dallas-Fort Worth. Emerson Collins’ flight. “These sounds started over the intercom before takeoff and continued throughout the flight. They couldn’t stop it, and after landing still had no idea what it was… I filmed about fifteen minutes, then again during service. It was calmer for a while mid flight.”
  • Mid-September – American Airlines, Airbus A320. Orlando, FL to Dallas-Fort Worth. Doug Boehner wrote, “This happened to me last week. It wasn’t the whole flight, but periodically weird phrases and sounds. Then a huge ‘oh yeah’ when we landed. We thought the pilot left his mic open.”
  • September 18 – American Airlines 1631, Santa Ana, CA to Dallas-Fort Worth. Boeing 737-800. An anonymous report passed on by JonNYC, “Currently on AA1631 and someone keeps hacking into the PA and making moaning and screaming sounds 😨 the flight attendants are standing by their phones because it isn’t them and the captain just came on and told us they don’t think the flight systems are compromised so we will finish the flight to DFW. Sounded like a male voice and wouldn’t last more than 5-10 seconds before stopping. And has [intermittently] happened on and off all flight long.” (And here’s a second person on the same flight.)

Interestingly, JonNYC followed up with the person who reported the incident on September 18 and asked if it sounded like the same voice in the video. “Very very similar. Same voice! But ours was less aggressive. Although their volume might have been turned up more making it sound more aggressive. 100% positive same voice.

Official Response

View from the Wing’s Gary Leff asked American Airlines about the issue, and their official response is that it’s a mechanical issue with the PA amplifier. The LA Times followed up on Saturday, with slightly more information:

“Our maintenance team thoroughly inspected the aircraft and the PA system and determined the sounds were caused by a mechanical issue with the PA amplifier, which raises the volume of the PA system when the engines are running,” said Sarah Jantz, a spokesperson for American.

Jantz said the P.A. systems are hardwired with no external access and no Wi-Fi component. The airline’s maintenance team is reviewing the additional reports. Jantz did not respond to questions about how many reports it has received and whether the reports are from different aircrafts.

This explanation feels incomplete to me. How can an amplifier malfunction broadcast what sounds like a human voice without external access? On multiple flights and aircraft? They seem to be saying the source is artificial, but has anyone heard artificial noise that sounds this human?

Why This Is So Bizarre

By nature, passenger announcement systems on planes are hardwired, closed systems, making them incredibly difficult to hack. Professional reverse engineer/hardware hacker/security analyst Andrew Tierney (aka Cybergibbons) dug up the Airbus 321 documents in this thread.

“And on the A321 documents we have, the passenger announcement system and interphone even have their own handsets. Can’t see how IFE or WiFi would bridge,” Tierney wrote. “Also struggling to see how anyone could pull a prank like this.”

This report found by aviation watchdog JonNYC, posted by a flight attendant on an internal American Airlines message board, points to some sort of as-yet-undiscovered remote exploit.

We also know that, at least on Emerson Collins’ flight, there was no in-seat entertainment, eliminating that as a possible exploit vector.

Theories

So, how could this happen? There are a handful of theories, but they’re very speculative.

Medical Intercom

The first to emerge was this now-debunked theory came from “a former avionics guy” posting in r/aviation on Reddit:

The most likely culprit IMHO is the medical intercom. There are jacks mounted in the overhead bins at intervals down the full length of the airplane that have both receive, transmit and key controls. All somebody would need to do is plug a homemade dongle with a Bluetooth receiver into one of those, take a trip to the lav and start making noises into a paired mic.

The fact that the captain’s announcements are overriding (ducking) it but the flight attendants aren’t is also an indication it’s coming from that system.

If this was how it was done, there’s no reason the prankster would need to hide in the bathrooms: they could trigger a soundboard or prerecorded audio track from their seat.

However, this theory is likely a dead end. JonNYC reports that an anonymous insider confirmed they no longer exist on American Airlines flights. And even if they existed, the medical intercoms didn’t patch into the announcement system. They only allow flight crew to talk to medical staff on the ground.

Pre-Recorded Audio Message Bug

Another theory, also courtesy of JonNYC, is that there’s an issue with the pre-recorded audio messages (“PRAM”), which were replaced in the last 60 days, within the timeframe of all these incidents. Perhaps some test audio was added to the end of a message, maybe by an engineer who worked on it, and it’s accidentally playing that extra audio?

Artificial Noise

Finally, some firmly believe that it’s not a human voice at all, but artificial noise or audio feedback filtered through the announcement system.

Nick Anderegg, an engineer with a background in linguistics and phonology, says it’s the results of “random signal passed through a system that extracts human voices.”

Anderegg points to a sound heard at the 1:20 mark in Emerson’s video, a “sweep across every frequency,” as evidence that American Airlines’ explanation is accurate.

Personally, I struggle with this explanation. The wide variation of utterances heard during Emerson’s three-hour flight are so wildly different, from groans and grunts to moans and shouts, that it’s difficult to imagine it as anything else but human. It’s far from impossible, but I’d love to see anyone try to recreate these sounds with random noise or feedback.

Any Other Ideas?

Any other theories how this might be possible? I’d love to hear them, and I’ll keep this post updated. My favorite theory so far:

Photoillustration of an American Airlines jet headed towards a scared cartoon cloud

Comments

    Don’t these aircraft without IFE have prerecorded audio safety briefings? Someone in maintenance might have done this as a gag, putting the official briefing first and then a lot of silence/noise, then the joke noises. That’s how I’d do it anyway.

    I wonder if there is an intercom in the animal section. The vocalizations sounded more like a goat and a dog. AA carries animal cargo in a separate part of the plane. If they made stove changes to that area to make it more comfortable for the animals or make it easier to monitor them, that system may be malfunctioning.

    Something similar happened to us on August 5th, flying AA from DFW to Portland (PDX). This was the actual text I sent to family: “Well we are boarded on our second flight but I think it’s haunted.” AA 2496. Our experience was a little different though. It started during boarding. The call lights turned on for every seat, the cabin lights were constantly flashing, and the flight attendant’s phone sound was dinging. There were bursts of static/white noise and occasional high pitched or low pitched sounds. The flight attendants seemed perplexed. They couldn’t use the PA system to make any announcements. The door to the flight deck was open so it clearly was not the pilots. They called maintenance and maintenance said that the cabin wiring was completely separate from the rest of the plane’s electric. They reset it, and the craziness finally stopped. We took off (this caused about a 20-30 minute delay) and nothing happened for the rest of the flight.

    My money is on some yet-to- be-determined technology hidden in somebody’s checked or overhead bags. The fact that these are on predetermined routes, and from takeoff to landing, leads me to think it’s passive, and not reliant on real-time moaning and groaning.

    These actually do sound like line noise squelches but modulated/gated down to human vocal registers. Maybe there’s some sort of speech synthesizer built in to the system that’s getting feedback somehow?

    Reminds me of the Mouth Play audio plugin for Ableton. After having played around with that one, it strikes me how much the noises sound like the artificial things Mouth Play makes.

    As such, my theory is that the sound travels towards a live mic, through tubes that emulate the a/o sound of an open mouth. And as the article mentions, things that don’t sound like a human voice are cut out of the recording.

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