This Hidden Danger Killed 68 People (American Eagle Flight 4184) - DISASTER BREAKDOWN

October 31st, 1994. Its Halloween. A small commuter plane was preparing to make its landing in the afternoon midwestern rain.

American Eagle Flight 4184 was a short flight from Indianapolis to Chicago. A journey of only 150 miles give or take. A total of 68 passengers and crew were on board the small ATR72 turboprop that afternoon.

The passengers may have been looking forward to arriving in Chicago but delays due to weather and air traffic congestion has been keeping them in the holding pattern south of Chicago. For flight attendant Amanda Holberg it was a special day, it was actually her first day on the job as a Flight Attendant. Flight 4184s destination was Chicago O’Hare international airport, one of the largest and busiest airports in the entire world.

It’s a complex and delicate act to keep air traffic moving in and out and dozens of aircraft arrive and depart from Chicago’s numerous runways every hour. Halloween 1994 was yet another busy day at the airport. Due to deteriorating weather conditions, management at the airport needed to change the traffic flow.

The poor weather forced them to close a number of the runways creating congestion. So a priority system was in place. Smaller planes like Flight 4184 were required to hold whilst larger planes with limited fuel quantities get priority.

Flight 4184 was already late in leaving Indianapolis; they had been on time earlier in the day but a lengthy delay on the ground thwarted their schedule. They were supposed to arrive back in Chicago at quarter past three that afternoon but faced even more delays when they eventually left Indianapolis at 2:55. Up on the flight deck of flight 4184 there were two young pilots at the controls.

29-year-old Captain Orlando Aguiar had about 8,000 total flight hours in experience. Around 1,500 of which was in this aircraft. He had extensive experience flying props for the airline getting his start in a First Officer’s position flying the British Short 360 planes.

The Captain was a well-loved pilot at his airline and was known for his relaxed approach on the flight deck. At home in his personal life his family was growing and though that day was supposed to be a day off, he choose to work more days to save money as he had a second child on the way. To his right was 30-year-old First Officer Jeffrey Gagliano.

As far as experience on the ATR goes, he’d actually spent more time on it that the captain with over 3 and a half thousand flight hours in the aircraft. Around 5000 in total. Jeff Gagliano, though he loved flying, if there was one thing he loved more, it was spending time on the Gagliano family ranch in Wisconsin.

He was actually thinking of giving up his flying career to pursue more work there instead. The previous weekend he helped his family run the ranch as it was busy due to Halloween related festivities. Mr Gagliano had a much younger 10-year-old sister who he promised to go Trick-or-Treating with on Halloween.

Sadly, he was rostered in to fly on Halloween instead. Like many pilots on the regional grind, October 31st, 1994, was a very busy day for them. Flight 4184 was only the second flight in their schedule and after arriving in Chicago they were to continue over to Dayton, Ohio returning to Chicago with another flight to Champaign, Illinois.

A busy day’s work and the delays weren’t helping matters. The plane the two men were flying was a French manufactured ATR72-200. The company ATR developed the plane as a joint venture between France and Italy.

The ATR72 and its smaller sister the ATR42 are a set of sleek turboprop plane popular in Europe. The ATR family first took to the skies in the late 1980s. This particular plane was actually brand new having only rolled off the production line earlier that year in March 1994.

In its short 6 month life it had managed to accumulate over 1,300 flight hours over 1,600 flights. The plane was almost constantly flown, buzzing in and out of Chicago throughout the year. Although the plane was not operated by American Eagle.

No American Eagle was only the branding. American Eagle is the American Airlines regional division of which a number of different airlines are contracted under. The plane actually operated to a company called Simmons Airlines.

This was also who the pilots worked for. Simmons though was acquired by the parent company of American Airlines AMR Corporation in 1988. This is actually a pretty common arrangement in the United States.

The larger carriers work with these smaller airlines to fulfil regional services. Because of this, these operators can carry the branding of American Airlines or Delta and have their planes painted to reflect as such. The plane has been in the air for nearly 15 minutes.

Flight 4184 was cruising at an altitude of just 14,000 feet. On frequency, a Pilot a small Beechcraft Baron General Aviation Aircraft transmits a message. They identify themselves and issue a report of “light icing” on their wings.

They made the report over the BOILER VOR at an altitude of 12,000 feet. So in the region of flight 4184. It’s cold and there are icing conditions enroute.

That’s okay though, the ATR72 like almost any airliner had been certified for operations in light to moderate icing conditions. It's 3:13, the pilots begin their descent down to an initial altitude of 10,000 feet. During the descent, the pilots notice themselves that they are in Icing conditions, that being in this case, in temperatures of less than 7 degrees Celsius in the presence of visible moisture.

So the pilots enabled the airplane’s Ice Protection, just like they normally would and didn’t think much of it. Five minutes later they report on frequency that they were now at this lower altitude of 10,000 feet. It was then at 3:18 that the Chicago Approach controller issued their holding instructions.

Up till this point the pilots had been following the V399 Airway. Having already passed the BOILER VOR, they were heading to their next waypoint BEBEE. Now they have been issued a holding instruction, this would bring them off of their flight path over to the LUCIT waypoint near the small rural town of Roselawn where they were to hold.

The pilots make the right turn over to LUCIT where they reported their position and entering the hold at 3:24 in the afternoon. By this time, the pilots have switched off the plane’s ice protection. From here the pilots will hold the plane in a pattern with legs of a few miles, complete a small circuit.

They’d do this, repeating the pattern until they could be cleared for an approach. This obviously meant further delays to their schedule. As such the pilots sent a message to Simmons Airlines via the Aircraft Communications and Reporting System, that’s ACARS.

After that there really wasn’t much for the pilots do, other than just wait. Now when investigators later retrieved the airplane’s black boxes and fired up the Cockpit Voice Recorder, the recording began from around 3:27 so shortly after the start of the hold. Right from the outset of the recording investigators heard something unusual.

. . Music.

The pilots had tuned one of their navigation radios into a local commercial radio station and according to one former American Eagle pilot, this was actually somewhat common. They put on some music to pass the time and even began chatting with the Flight Attendants, in what I’m sure is a highly relatable moment for many of us in our work lives. At 3:28 the First officer even says for a moment that he was distracted.

Moments later one of the Flight Attendants walks in and begins a very casual, joking conversation about their jobs. Its highly relaxed atmosphere, but the delays were on the minds of the crew. The Flight attendant here even says that at least two passengers have already missed connecting flights.

Over the next few minutes, the crew would be engaged in this conversation, that was until the pilots noticed a bit of a high angle of attack. Captain Aguiar comments on this. .

. “Man this this gets a high deck angle in these turns” he says. “We’re just wallowing in the air right now” Jeff responds.

“You want flaps 15? ” “I’ll be ready for that stall procedure here pretty soon” “Do you want kick ‘em in, it’ll bring the nose down” “Sure” Bringing the flaps out at a slower speed reduces the angle of attack and the nose drops. The pilots comment that the Flight Attendants would have noticed this change.

Five minutes later the controller issues an estimated time of 4pm as to when they could expect a further clearance, effectively meaning they’ll still be holding for a further twenty minutes. In the meantime, the crew return to conversations with the Flight Attendants. But there was a chime at 3:41 that sounded in the flight deck, to alert the pilots of icing.

In response the Ice protection was switched back on and the props were increased to a setting of 86%. This was an appropriate response for flying this plane in icing conditions. By this time, they had begun their third circuit in their holding pattern.

With them still not expecting further clearance for another 18 minutes the pilots send another ACARS message to their airline to update them on their situation. 3:48. The First Officer verbally comments, “I’m showing some ice now”.

The plane’s ice protection was activated and one minute later the Captain left his seat and made his way to the aft cabin to use the lavatory. The restroom was occupied by a passenger at the time so to pass that time, he talked with a flight attendant and picked up the intercom to inform the First Officer that he’ll be back as soon as he could. Five minutes later the Captain returned to the flight deck having used the restroom.

Moments later the First Officer would again advise the captain of ice accumulation. The Captain didn’t really acknowledge it, and this would be the last mention of ice from either of the pilots for the rest of the flight. There was a very brief TCAS alert on the flight deck.

Probably just picking up on nearby traffic but nothing really for the crew to worry about, it wasn’t even acknowledged by them at all. ATC shortly thereafter radioed in an update notifying them to expect further clearance in ten minutes time, so now they’d be looking at about 5 minutes past 4. 3:57, Flight 4184 was cleared for a further descent down to 8,000.

The plane was still in holding so the plane entered a nose down, 15-degree right turn. As they had previously extended the flaps, the increase in airspeed brought on by the descent triggered the Flap Overspeed Warning. .

. “I knew we’d do that” The Captain says. The First Officer responds, “I was trying to keep it at 180”.

Referring to Airspeed. Obviously as they were now in a flap overspeed scenario, the pilots chose to do the logical thing, retract the flaps. They select a position of 0 so fully retracted and the flaps are brought back in.

As a result the plane’s attitude changes to reflect the changing wing. Seconds later, an ominous repetitive thumping sound reverberating throughout the plane. Then without warning.

. . It was as if the flight controls, specifically the ailerons snapped to the right.

There was a massive, uncommanded deflection of the ailerons, resulting in a sudden roll. This as you can imagine severely disturbed the previously casual, cordial atmosphere on the plane. The ATR plane banks sharply over to the right to a maximum of 77 degrees, so a highly excessive roll that the plane should really never perform.

The autopilot disconnects due to the sudden change in the flight controls. The pilots don’t say a word, too stunned to speak they arrest the roll and bring it back to a relatively neutral position. It is believed that the pilots applied a great amount of force on the controls to bring the plane level, as suggested by the heavy breathing, expletive remarks on the voice recording.

The plane during this first upset, the nose drop greatly. For a period of about 5 seconds, it looked as if the plane returned to normal and the nose began to rise from a nose down attitude. This entire upset, occurred within a five second window.

From the onset at 3:57 and 33 seconds and 3:57 and 38 seconds. The plane rolled, the pilots quickly responded and arrested the plane and began recovery. Following this tiny window of time however, the plane violently rolls again to the right.

This time, the bank exceeded a rolling rate of 50 degrees per second. This time the pilots experienced a total loss of control. They simply couldn’t recover the plane by use of their control wheels.

It was as if some sort of force was applying great pressure on the controls, far beyond their own strength. What they had managed to do was apply nose up inputs on their flight controls. Flight 4184 inverts and the plane’s altitude begins to rapidly decrease.

The Indiana Countryside emerges from the clouds in full view of the pilots and passengers. At its maximum, the plane reached an extreme bank angle of 144 degrees, but at the same time with a 73 degree nose down attitude. Now below 5000 feet, the pilots arrest the roll and slowly begin to pull the plane out of the erratic dive.

They are slowly regaining control of their plane however, they sadly run of time. There wasn’t enough altitude left and American Eagle Flight 4184 crashed into a Soybean field just outside the rural town of Roselawn, Indiana. When investigators got to the site, the discovered that no one had survived and had actually declared the site a biohazard.

The aircraft was obliterated but there was no fire after the crash. The news quickly spread and within an hour media outlets began reporting on the incident. It made headlines in the local 5 o’clock news.

What followed was a lot of speculation into what caused 68 people to lose their lives that day. When it was found out that this was a small commuter plane flown by two young pilots a narrative of inexperience flight crews began to take hold. At the crash site investigators made a number of initial observations.

They could account for the four corners of the plane, the nose, tail, and wingtips. A clear sign to investigations the plane had crashed largely whole. Although the parts were found in a particular patter that suggested that an inflight breakup did occur but very low to the ground in those final seconds before the crash.

The Horizontal Stabilizer and Wingtips were torn off, whilst the nose was found further ahead with much of the other wreckage. The pattern of the main debris field in a sort of V shape, gave an indication on how the plane impacted the ground. The plane crashed at a shallow angle, and as investigators noted partly inverted.

Investigators retrieved the data from the flight recorders and data from local Air Traffic Control. ATC was cleared of any wrongdoing. Working with the available data they had at the time, the directly the aircraft accordingly.

As for the Flight crew, though investigators may have seen the actions of the pilots to have been perhaps unprofessional, chatting with flight attendants about non flight related subjects, having the radio on stuff like that, though perhaps unprofessional, it was concluded that this didn’t contribute in any way to the crash. This accident , it really can’t be overstated just how horrible it was. But we have some unanswered questions here.

It’s not normal for a plane to behave that way. Form the pilots perspective it just seemed to lose all sense of control, as if the flight controls had a life of their own. Very quickly, in a matter of days infact, investigations identified the culprit in this case.

Ice was present and was a causal factor in the crash. This obviously brings in to question the weather at the time of the accident. Let’s take a moment to look a bit deeper at the specifics about those weather conditions the plane flew into.

-break- Well it’s that time of the year where things start getting cold so maybe it’s a good time to talk about ice. It would be all well and good for me to stand here say that flight 4184 flew into icing conditions allowing ice to develop on the wings creating a disruption of airflow but that’s getting ahead of things. To really to understand this accident at the appropriate level and enable further understanding as to how ice could have contributed to a loss of control like the event seen on the accident flight, we first need to have an idea of what Flight 4184 actually flew into.

First of all lets breakdown the general weather conditions at the time. Now during the flight, no SIGMET (Significant Meteorological Report) had been issued, but the controller was clued into light icing in some regions and even had some pilot reports. So the controllers were aware of the presence of icing that day and were trying to sus out areas of potential icing risk.

Where flight 4184 was holding at the LUCIT waypoint, no significant weather had been reported at that time. But what actually was the weather like? Well my friend, lets dig through the meteorological records.

We have weather maps from the time where we see in the preceeding days a cold front had passed over the Midwest. This enabled an environment where a low pressure system could move in from the North from Canada bringing frigid air temperatures with it. This manifested on the day of the accident as a cold, wet, foggy, and windy Midwestern Day.

The high moisture content of the air was the result of the warmer regions to the south, so there was that confluence of weather systems. Taking weather observations from Chicago, Gary, Indianapolis, Layfayette and South Bend, we can paint a good general picture of the weather that day. Winds were blowing from North-Northeast, with gusts in excess of 50 knots, clouds were low with some stations reporting a base of just 1,000 feet, visibility was as low as 3 miles with rain showers all over the Midwest.

Temperature in Chicago, anyway, reached a high of 7 degrees Celsius that’s 44 Fahrenheit. That was reached at about midday, in the afternoon the temperature began to dip. As you climb in altitude, the air temperature does begin to drop further and, in this case, where flight 4184 was holding at 10,000 feet, the temperature was just below freezing.

In the sky, the clouds extended a high as 18,000 feet which you’ll note was actually even higher than the cruising altitude of flight 4184’s 14,000. So the big question presents itself, what was in those freezing clouds? Okay so this brings us onto the next part.

The thing Flight 4184 actually flew into and is so important to how this accident played out. What specifically was in these clouds? We need to talk about SLD.

Supercooled Large Drplets. SLD forms in clouds where the temperature is cold. The droplets are below freezing temperature and the moisture is in its purist form.

These clouds right where flight 4184 was holding, held just the try conditions for SLD. These Supercooled Large Drplets are typically larger than other droplets and pose a great hazard for aircraft because they create ice that exceeds typical icing conditions that planes are certified for. Therefore should always be avoided.

Don’t get this wrong though, these might be called “Large Drplets”, but these things are still tiny. At best 2mm in length though I have heard from some sources that 5mm is their potential. Regardless, pretty small.

But it’s that first word. . .

Supercooled, what does that mean? I want you to think about basic science here for a moment. We all know that water has a freezing point of 0 degrees Celsius, 32 degrees Fahrenheit.

At this temperature you can expect water to freeze and become ice. Simple enough. But what if I told you that there exists a state of water where though its temperature is below freezing, it remains a liquid.

That is what we mean by the term “Supercooled” That’s what it is. A liquid that exists as a liquid below its freezing point. So why does that happen?

For water to freeze it requires an additional process called nucleation. A term in thermodynamics that we can best be summarized for our accident analysis today, as the starting point of a transition from a liquid to a solid. So it’s basically the center of the freezing where the molecules become attracted and bind themselves together to form a solid, in this case ice.

But as it turns out, the line between ice and water isn’t so straight forward. There does exists a small window where water can be cooled slightly below its freezing point for a period of time and not become ice because nucleation has not yet taken hold. I mean it will if you give it enough it time but that’s not the point.

We have freezing water that’s not frozen. If there is one thing that supercooled water needs its purity. That’s because nucleation can be tripped by small fragments of dirt or debris anything that can give it that little bit of energy to trigger the process.

You can see it best in this video. We have supercooled water, below freezing as a liquid but when its disturbed it becomes ice, it’s fascinating. This brings us back to Flight 4184.

We have droplets of this supercooled moisture coming from these frigid clouds and where is the nucleation point for it to turn into ice. The plane itself! The Supercooled droplets hit the plane, triggered nucleation, and quickly froze on its surface.

Resulting in an accumulation of ice on the plane’s wings. And that is how the ice got on the plane. -break- We have now established how Ice accumulated on the wings of the ATR72.

However there are further questions to answer here. In this segment we’re going to familiarize ourselves with the Ice protection systems of the aircraft which will lead nicely how the ice accumulation crippled the performance of the plane to the point of loss of control. This ultimately gets us to the heart of this accident.

First of all, planes can fly safely in cold weather. It happens all the time. A lot of work has gone into making aviation safe in cold, winter, icing weather.

Whether that be from de-icing equipment on the ground to onboard anti ice protection systems. We have known for a long time the negative effects that ice has on aerodynamic performance. There are guidelines in place that pilots and airlines should adhere to, to guarantee safe operation in this type of weather.

Plane’s may fly into ice and even collect some on its surface but again there are guidelines for what is and is not acceptable and every plane needs to be certified for ice operations. Okay so we know ice is not ideal, it does present a problem for airliners. Ice disrupts what is otherwise the smooth air flow over the wings.

That airflow is necessary for the wings to function as needed and sustain the necessary lift output to keep the plane aloft. Disrupting that process with ice with its unevenness, its irregularities, creates a lot of drag, could lead to airflow separation, reducing the lift output. Ice buildup also adds extra weight.

This all means the plane will require more energy to maintain level flight. In severe icing if it becomes necessary, pilots will lower the nose, descend to maintain airspeed. That is why planes have anti-ice and deicing tools on board.

The ATR 72 is no different in that regard. So let’s take a moment to familiarize ourselves with this aircraft’s anti-ice and de-icing tools. There are increments to the ATR’s Ice Protection, Level 1, Level 2, and Level 3.

Level 1 ice protection is always switched on and serves to heat the pilot windshield and keep the sensitive external probes clear of ice. Electrical heat supplied by the plane’s battery fulfils this function. Things get a bit more interesting when looking at Level 2 and 3 Ice Protection, which should be activated by a pilot during icing conditions.

Level 2 is engine and structural anti-ice prevention, and Level 3 is actual de-icing, physically removing ice from the plane. Exploring Level 3 Ice Protection further, the ATR72 and other planes like it have a very distinctive feature on the leading edges of the wings and stabilizer. These long black areas, these are called de-icing boots.

A pneumatic system injects air into the boots, which inflate, and breaks off any ice that has accumulated on the leading edges. I think one question that a normie might have here is, “if these systems protect against ice, and ice is unfavorable for flight, why not just keep the ice protection systems on all the time”. I think for people who are not familiar with intricacies of airplanes, this is a valid question to ask.

At the end of the day, for these systems to work, the require some sort of air source. Whether it be for the propeller anti-ice, air frame anti-ice or the deicing boots, the source of that is bleed air. That being air that has been siphoned off from the air intake process, taken away from the engines for uses elsewhere on the plane.

Engaging the anti-ice leads to a slight decrease in engine performance. So where necessary, pilots switch these systems off to get the most from their engines. Additionally, the heated bleed air could result in eventual damage if excessively used.

Let’s get back to those de-icing boots. It’s an instant fix but a problem as already presented itself here. As we have already established, flight 4184 flew into rain and was in the presence of Supercooled Large Drplets that froze when they came in contact with the plane.

Now if we go back to the diagram, one of the properties of Super Cooled Large Drplets, means it can slide back over the wing to the region beyond the deicing boot. Normally ice accumulates on the leading edge but SLD-ice covers a larger area that the de-icing boots can’t reach. The pilots had lowered the nose during their holding phase by extending the flaps.

Though the intention here was to provide a more comfortable experience to the passengers, this also exposed the supper surface of the wing to more SLD. Though the ATRs ice protection was doing a good job of protecting the wing’s leading edges, that doesn’t mean the rest of wing was getting treated and ice built up behind the deicing boots, in fact this supercooled condition could result in a ridge of ice aft of the boot. Basically, what was allowed to happen here was though the pilots had engaged Ice Protection, ice was still building up on the wings.

Also because the ATR72 is a high wing aircraft, they had no way to see it from the flight deck. None of this however fully explains the loss of control, we’ll get to that. But it was at this point of my research that this book turned up at my door.

This is “Unheeded Warning” Written by a man by the name of Stephen Frederick. Look at all my notes. Stephen Frederick was a former American Eagle ATR72 pilot.

He was actually close friends with First officer Gagliano who was sadly lost in the accident, the two were hired together by Simmons Airlines. For the author, the effect of this accident was personal. In this book, Mr Frederick tells his experience of this accident and the fallout that came afterward.

He wrote of how he was working nightshifts at the time and was actually asleep when news broke of the disaster. He was woken up by a panicked telephone call from his Mom as she had just seen the report on CNN. Former Pilot Stephen Frederick knew a thing or two already about the ATR72s icing problems.

He had previous experience at the controls of an ATR72 experiencing flight control difficulties in a snowstorm. The previous year during the Thanksgiving Holiday of ’93. He was flying an approach into a cold, icy Marquette, Michigan.

It was snowing and as he was just a few hundred feet from the ground he felt what he described as “a powerful rhythmic vibration” and felt the control wheel wanting to oscillate, almost as if there was some external force acting on the flight controls. After applying maximum prop speed, aborting the landing, leaving the snow storm, and diverting elsewhere this American Eagle Pilot just knew that ice could be fatal. When he received news of Flight 4184, he took upon himself to investigate this further.

It wasn’t just him; other pilots began to speak up with concerns about the ATR aircraft’s performance in icing. He reports how pilot morale was shattered after the accident. Now as it turns out, the tragedy of flight 4184 was just the latest in a string of incidents involving the ATR misbehaving in ice.

Multiple pilots at American Eagle endured incidents and ice is believed to have claimed lives years before the Roselawn Disaster. In 1987, a brand new ATR 42, the small sister of the 72, crashed north of Milan near lake Como in Italy. Resulting in the deaths of 37 people.

It was ice related but the cause was disputed. ATR said pilot error was to blame. Air Crash Investigators pointed to Ice and the performance problem involving ice accumulation we’ve already discussed.

The pilots lost control, didn’t recover, and crashed. Though multiple other anomalies were reported by pilots, ATR, the plane’s manufacturer made no changes at that time to address it. Now ATR, when they unveiled the plane in the 1980s, developed it with a sleek design with high performance in mind.

Like any aircraft manufacturer they know the value of efficiency and the ATR family was designed to increase Aerodynamic performance, decreasing drag whilst optimizing for lift. Sounds like sweet deal. But despite this design, pilots would complain and issue reports of significant ice accumulation.

Now this wasn’t such a big problem for many European Carriers even those in colder climates. For example, take the Finnish National Airline, Finnair. Finnair has been a long time customer of the ATR family going back to 1986 and continues to fly them to this day.

They have successfully flown the ATRs without incident. However, put the ATR in an environment like Chicago, one of busiest airports in the entire world, suddenly ATR pilots now have to operate within tight margins. As Stephen Frederick put it, the flight envelope was narrowed as pilots were required to adhere to more restrictions around Chicago.

Something that only got worse as time went on, working against the performance of this aircraft in icing conditions. At American Eagle alone, there were at least a dozen icing related incidents and mishaps, prompting concerns from pilots. But don’t take this the wrong way, this plane the ATR is objectively a good plane.

Perhaps it needs to be mentioned, any plane suffers performance problems in ice not just the ATR. But here we finally reach the bottom of the mystery. It basically suffered from a quirk of the wing’s design.

Remember that air flow separation, lets revisit that. We talked about how ice got on the plane, built up and how the deicing boots failed to clear the wings of ice. .

. Well carrying on from that, on the accident flight, this effectively created a performance shadow where the ailerons are located on the trailing edge of the wings. That void means that the ailerons are now susceptible to something called an Aileron Hinge Moment Reversal.

An area of low pressure had been created over the trailing edge of the wing. So what happens, naturally the aileron is influenced by the volatile air now in this region and the aileron lifts, its pulled up. On Flight 4184, this occurred on the right wing.

The right aileron was lifted up from this force. And what do you know, this is our uncommanded aileron deflection. This led to the loss of control on Flight 4184.

Critically leading up to this moment, seconds before disaster struck the pilots retracted the flaps back to zero. The effect of this was an increase in the angle of attack, which only made the plane vulnerable to that break of the wing’s much needed airflow. The environment for this disaster was set as by that point, ice had accumulation on the wings reached a critical level, airflow separated at a higher angle of attack inducing aileron hinge reversal.

When the ailerons deflected with the force they did, it was excessive to the point the pilots had to apply all the strength they could to recover the plane, and they did for a brief moment until it happened the second time. The ATR family does not have hydraulic powered primary flight controls. The control wheels on the flight deck are directly connected to the flight control surfaces via a complicated series of cables and pulleys.

When an ATR pilot acts on the control wheel, they get an immediate response back from the plane. Problem here is, that process also works in reverse. The pilots felt every bit of those uncommanded deflections coming through to the control wheel.

That volatile air lifts the aileron, the control wheel moves in response and only the strength of the pilot can counteract it. -break- Okay, so this was something that ATR pilots in the American North sort of just put up with. The planes would vibrate, experience rolling anomalies and pilots reported inconsistencies in their ailerons and it was something that was just sort of accepted by Pilots of Simmons Airlines and American Eagle.

The ATR had developed a negative reputation associated to ice amongst pilots at the airline, to the point that some even refused the upgrade from the smaller Short 360 despite the increase in pay. Pilots at Simmons Airlines/American Eagle grew ever more concerned. It wasn’t a problem that for the airline, could just go away.

They had dozens and dozens of these things in the fleet. The ATR fleet was a $2 and a half billion dollar investment. So the airline attempted to drum up support for the plane and increase morale, but it wasn’t happening.

Many pilots saw right through the company’s attempt to gloss over the problem and in ways, the airline made this worse. There were notices given to the pilots requiring them to adhere to new airspeed margins whilst holding and to bring the flaps in at lower airspeeds. It was all very confusing to the pilots who found that these recommendations from their airline were in conflict with basic pilot sensibilities.

They were now required to fly really slow with 0 flaps. Some changed their approach to flying, others continued with their tried and true methods, and even still there were those who swore by never going below 210 knots in icing which was actually higher than what ATR recommended. There was even a point where Simmons reportedly asked its pilots to attempt to differentiate between raindrops and avoid areas that could contain supercooled and freezing rain.

Ignoring the fact that differentiating raindrops while flying through the air is difficult. Supercooled Large Drplets was something that few pilots at the time were clued into. It was only after Roselawn that extensive experiments with the help of NASA did our understanding of this phenomenon grow.

We can now even detect and forecast SLD conditions. None of this though helped to cool the atmosphere of the American Eagle crew rooms. Pilots got into arguments; numerous pilots refused to fly the ATRs leading to cancellations of flights.

As Stephen Frederick reports, “people began throwing things and slamming doors in the crew lounge”. It was a tense time at the airline. Everyone was keen to know what the investigation would find but a lot of these pilots kind of already new the score.

Weeks passed with little done from the airline or manufacturer to address the concerns of pilots. A number of American Eagle pilots then took this to the public. About three weeks after the accident, just after Thanksgiving, during the very busy travel season, something began to show up throughout the airport terminals.

Notices, flyers, warning passengers of this danger. They appeared in the airport shops, bathrooms, phone kiosks, on tables and chairs and even distributed directly to passengers. Pilots were protesting, directly confronting the flying public to tell them “Hey we don’t think this plane is safe on a cloudy rainy day”.

Stephen Frederick was one of those pilots handing out these leaflets. This is what it said. .

. “WARNING! American Eagle Passengers.

Despite all of our warnings and past experiences, 68 people died needlessly on October 31st, 1994, in the crash of American Eagle Flight 4184 in a soybean field between Indianapolis and Chicago. This accident did NOT have to happen and the FAA, American Eagle management, the Airline Pilots Association and ATR (manufacturer of the ATR aircraft you will be flying in on your trip today) could have prevented it. American Eagle (Simmons Airlines) has had between 8 and 12 REPORTED incidents (and many many unreported incidents) related to the LOSS OF CONTROL or IMMINENT LOSS OF CONTROL due to ICE on wings and tail surfaces over the past 8 years.

Only luck saved these aircraft, several of which were recovered by the flight crews just SEVERAL HUNDRED FEET ABOVE THE GROUND. The pilots of these aircraft have pleaded with the company and FAA to review the certification of these aircraft in light of each and every ICE incident that occurred over the years. MONEY has been a motivating factor in denying any in-depth investigation, and now 68 people have paid the ultimate price.

The pilot group of this airline are irate, and we need your help! Please review the information on the reverse side of this flyer and help pass this along to the press, attorneys and congress. It may take congressional hearings to make these aircraft safe during icing conditions.

The FAA, ALPA and the company have successfully swept past incidents under the carpet in the interest of PROFIT. Much more information is available! We the American Eagle pilots, are highly trained professionals and will do all we can to make your flight a pleasant and safe experience.

If the weather is clear this winter, sit back and relax because this is a good aircraft. If the weather is cloudy, snowy or cool and rainy, think about alternate transportation methods because the majority of us will refuse to fly these aircraft until the icing problems are fixed. Even with the threats of management hanging over our heads, we will exercise our rights as the “ultimate authority” of the flight and protect your safety.

Thank you”. So things were going from bad to worse at the airline. As far as American Eagle, American Airlines and its then Parent company AMR corporation was concerned, this was only the beginning.

The media took notice. On November 30th, 1994, the Chicago Tribune Newspaper ran the story of pilots refusing to fly the ATR right there on the front page. That very same day, an editor at the Chicago Tribune contacted our whistleblower Stephen Frederick as the story had captured the interest of producers over at the American Broadcasting Company.

They wanted to run a segment on the American Eagle story on Good Morning America. So the following day Mr Frederick appeared in silhouette for a televised interview, he was supposed to be anonymous. However there appeared to be a breakdown of communication between him and the producers.

When asked as how he’s like to be addressed, thinking they just meant for communication off air, he replied “Steve”. Problem is that was how he was introduced on television. He wrote about this moment, saying he knew from that instant when the host introduced him as “Steve” that he was finished at the airline, his cover was blown.

Though the whistle had been blown and the public were now aware of the ATRs ice predicament, tension was high at the Simmons Airlines and American Eagle. Some pilots supported the media coverage, others didn’t. Regardless, this public awareness campaign regarding the ATR was having an effect.

The public opinion on the aircraft soured. In response, Simmons put together a counter campaign in the following days. However on December 9th, the Federal Aviation Administration grounded the ATR in known or forecasted icing conditions.

It was devastating to the airline’s operations during the winter. It didn’t last though and by February restrictions were loosened and the plane was back in the cold sky again. Stephen Frederick was suspended from the airline.

-break- In this video we have covered the disaster of American Eagle Flight 4184. We’ve looked into the weather the aircraft was flown into. We’ve looked at the impact that ice had at that critical moment and even established how Aileron Hinge Reversal created an uncontrollable nightmare for the pilots, subsequently leading to loss of control and ultimately the crash that killed 68 people.

If there is one thing that needs to be remembered, it’s that this disaster did not have to happen. This specific issue with this plane had been known about for years, yet nothing was done. The plane’s manufacturer never took steps to improve the plane’s performance and American Eagle continued to fly the plane in icy weather despite pilot concerns.

The National Transportation Safety Board agreed with those American Eagle pilots that ice and the aircraft’s susceptibility to it was causal in the accident. French investigators at the Bureau of Enquiry and Analysis for Civil Aviation Safety (that is the BEA for short). They disagreed somewhat with the NTSBs findings.

Everyone was in agreement at least that there was a massive aileron deflection, it’s just that European investigators weren’t convinced ice was necessarily the culprit. They drew attention to the flaps. They said that they were flying at excessive airspeed with the flaps set to 15 degrees which could induce significant loads on aircraft.

They also highlighted that the pilots were engaged in non-pertinent conversations and French investigators put the accident down to pilot error. The NTSB refuted these points and stands by its findings. In the aftermath investigators found that the Federal Aviation Administration’s own certification process for aircraft in icing conditions was inadequate and recommended changes to properly certify these planes.

The NTSB also pointed fingers at ATR inadequate response to a string of known icing related incidents. No changes were made to the plane despite warnings. In fact, engineers at ATR had known about the plane’s problems in icing.

But the plane was certified anyway with procedures which they believed were adequate with dealing with the problem. They attributed incidents with the plane, as a sort of failing to follow their guidance. It was only after this accident that substantial changes were made.

The de-icing boots were extended to cover a greater area of the wing. New ice procedures were brought in, and pilot training was adjusted. The Federal Aviation Administration issued air worthiness directives aimed at smaller turboprops with specific reference to the hazards posed by Supercooled moisture.

In the years after, American Eagle took all of the ATRs south to warmer climates. Many of them operated in the Caribbean. You know, regions where icing is not much of a great concern.

Because of the Roselawn accident and the hard lessons learned, the skies are now much safer for all of us. Patreon Outro Hello, hello everyone. I guess it is that time.

The end of the video. If you found this one interesting be sure to drop a like down below, subscribe and let me know what you thought. I look forward to reading all of your comments.

If you can get a hold of a copy, I would actually recommend giving unheeded warning a read, that’s the book written by that Former American Eagle Pilot, Stephen Fredrick. It was an interesting read and insightful to here the account of someone pretty close to what we’ve discussed today. The book is not that common to my knowledge so if you do find a copy, pick it up.

It even includes a whole section looking into the background of many of passengers , a lot of stories there. Speaking of books and actually have in my hand, another book about an air disaster that is going to be very useful for a video that is coming in December. Its not the next video but maybe 2 to 3 videos from now that is going to be a big one that.

. . well, I don’t want to say too much yet, but you’ll wanna stay tuned for it.

All I will say is that it involves going out on location. Something I have done before but definitely not to this extent. Something else I want to bring up with you today is what’s going to be happening in the New Year.

January is going to be a pretty slow month production wise for videos. The reason being is that I have to travel for surgery, and I’m required to be in recovery in a hospital for two weeks. Thought I’d let you know this that’s going to be mid-January.

I will make sure that there’s a video in place to go out just before I leave but when I return, it’ll be with possibly the most requested video I’ve ever had. If you would like to follow more on that, you can always come on over to my twitter where I post many personal updates. Anyway, with all of that said, I must take a moment to thank my amazing Patrons over on Patreon for continuing to support the channel, you’ll see their names on the screen right now so if you see your name here a massive thanks to you.

Shoutout this to Clover Phoenix and Landon who pledged at the mid tiers, thank you so much. Big thanks to those who pledged at the highest tier in recent weeks, Andrew Oliva, Addison Gonzales and June Darius. I really appreciate that, you guys never had to be so generous but I really appreciate it, legends.

Total Legends. If you yourself would like to support the channel further and help make these longer videos possible, you can always join the Disaster Breakdown Patreon from just £1 per month and the link to that will be in the pinned comment below. All patrons get early access to all new videos, two days before they go out publicly on YouTube.

Okay I’m going to shut up now because this might be the longest outro segment ever. So thank you all so much for watching, have a great day and I will see you next time. Goodbye!