Summary:In episode 59 of Take to the Sky: the Air Disaster Podcast, we explore Crossair Flight 498, which crashed shortly after takeoff on January 10, 2000 outside Zurich, Switzerland. The investigation finds a combination of variables that led to the crash and a cockpit of confusion: we think you'll be as surprised by the twists and turns this story takes as we were!
Listen, Review, and Subscribe on:
Sources consulted for this story:
- Crossair Flight 498, Wikipedia
- Air Disasters, Lost in Translation. Episode 5, Season 3. Smithsonian Channel
- Crossair Flight 498 CVR Transcript. Tailstrike.com
- Crossair Flight 498 Accident Report, Federal Department of the Environment
- Transport, Energy and Communications
- Thomas Stocker, AIN Online. Avionics confusion had hand in Crossair Saab 340 accident
- Interface Design & Crossair Flight 498
- Crossair – SAAB – SAAB 340B (HB-AKK) flight CRX498
- Dave English and Michael Kuzel, University of Arizona. Reliability of Eyewitness Reports to an Aviation Accident (2014)
- Jeremy Hsu, Live Science. 2009. The Real Reason Cell Phone Use Is Banned on Airlines
- John Blau, Network World. Study: Mobile phones still threat in aircraft
- Kieran McCarthy for The Register. Mobile phone brings down Slovenian airplane
Read the Story!Expand the text below to read more about this episode.
How a Cockpit of Confusion Led to the Crash of Crossair 498
In episode 59 of Take to the Sky: the Air Disaster Podcast, we explore Crossair Flight 498, which crashed shortly after takeoff on January 10, 2000 outside Zurich, Switzerland. The investigation finds a combination of variables that led to the crash and a cockpit of confusion: failure to engage autopilot, making an incorrect turn, language barriers between the flight crew, and a cockpit display that led to confusion about the plane’s bank angle.
Crossair Flight 498 Disappears from Radar Shortly After Takeoff
It is shortly before 6 PM on the evening of January 10, 2000, and Crossair Flight 498 is waiting to takeoff from Zurich International Airport for an hour-long flight to Dresden, Germany. Flight 498 is a popular commuter route, frequented by area business travelers.
Flight 498 is a Saab 340B, which is a Swedish-made twin-engine turboprop commuter plane with 33 seats. The aircraft is known for short-haul flights between cities, and to pilots, the aircraft is known for having a comprehensive autopilot system which ensures the plane flies accurately. The Saab 340B is also known for being easy to control and for offering a smooth ride to passengers.
The three-person crew on Flight 498 is made up of Captain Pavel Gruzin, 41, and First Officer Rastislav Kolesár, 35, and one flight attendant. Captain Gruzin had 8,100 hours of flying time, with 1,900 in the Saab 340 type. He was described by others as being a role model and teacher, as a superior with an influence on the selection of crew members and their evaluation and career opportunities. First Officer Kolesár had about 1,800 total hours, with 1,100 hours in the Saab 340 type, and was described by fellow pilots as loving to fly – when he ever talked about flying with family and friends, they said you could see his eyes light up – that’s how much he loved it.
After the seven passengers and three crew members boarded, the plane was cleared for takeoff on time at 5:54 p.m. The aircraft departed Runway 28 heading west. From takeoff, the plane climbed normally. As Flight 498 climbs, the control tower makes a slight change to the flight’s intended path and asks the flight crew to make a left turn that would loop them south of the airport. But oddly, the plane begins to turn right instead of following the approved flight path to the left. And it’s not just turning to the right – it’s banking to the right.
When air traffic controllers radio the flight to say, “Crossair four nine eight, confirm you are turning left”, they were answered with a "Stand by," followed by a loss of radio contact. And then the unthinkable happens: Flight 498 disappears from radar.
Witnesses driving near the airport at that time recall seeing a small plane falling through the sky in a right-hand spiral dive, coming down toward the ground at a high rate of speed – and then the plane explodes into the ground and creates a massive fire ball across the dark, evening sky. Flight 498 has crashed in an open field near Zurich. All 10 people onboard have perished, including the three crew members and seven passengers.
Swiss Accident Investigation Board Investigates Cause of Flight 498 Crash
The Swiss Accident Investigation Board soon arrives at the crash site to begin examining the wreckage. The aircraft was destroyed when it crashed onto open meadow land, and after the crash, some items of debris were still burning on the surface. The majority of the wreckage penetrated up to 10 feet into the soft soil of the field. Smaller parts were spread in a fanlike formation in the direction of impact over a much larger area.
The lead accident investigator for the crash commented in an interview for the Smithsonian Channel that the crash scene, as we might imagine, was a complete mess. He said, you never knew what you might touch next – a human body part or a piece of the aircraft; it was a hard job.
What the crash site does tell investigators is, due to the depth and existence of the impact crater, the aircraft hit the ground at a high rate of speed and at a steep angle. This also matches what witnesses reported seeing as the plane was crashing to the ground. Investigators can also tell, based on the wreckage pattern, that Flight 498 was coming from the wrong direction and was turning the wrong way (turning right instead of left).
Investigators also check in with air traffic control, who explains that they were trying to give the crew a short cut when giving them the instruction to turn left. The new heading was a slightly shorter route to Dresden. This is a common practice done by controllers, and short cuts can save pilots minutes off a flight, which is very much appreciated. Investigators then wonder, why did the flight crew not follow the controller’s directions and turn left? When the controller saw the aircraft deviating from the path and go back to turning right, he just assumed the crew wanted to go a different way, and seeing no conflicts with air traffic, approved the aircraft going in the different direction.
This is an extremely important clue, and the discovery of this clue leads investigators to wonder, was this wrong direction caused by something within the plane’s overall performance, or was it caused by pilot error.
Investigators Rule Out Several Likely Causes of Flight 498 Crash
Investigators can immediately rule out several aircraft-related causes of the crash.
The investigative team goes layer by layer through the wreckage, inspecting aircraft parts for evidence of mechanical failure. A major point of discussion among investigators is, did the aircraft experience a mechanical failure of sorts, because that would certainly explain a loss of control and the subsequent crash. But the engines are found to have been functioning properly and were even running on high speed. The damage they experienced was from the impact, not form anything related to performance. Therefore, engine failure is ruled out as the cause of the crash.
Investigators also consider if an inflight fire played a role as several eyewitness report seeing the plane on fire as it crashed to the ground. Because fire leaves distinctive scorch marks on a plane’s fuselage, investigators must examine parts of the wreckage for indications of an inflight fire. In the end, investigators determine that the plane was not on fire as it was crashing to earth; the only fire it experienced was from the impact.
Interestingly, this dynamic with witness accounts is common in air crashes – some of the information is either wrong or reported in an incorrect sequence. A study conducted by Dave English and Michael Kuzel from the University of Arizona in 2014 found that there are many variables known to influence eyewitness accuracy. Memory of an event can by changed by exposure to misinformation about the event, by reactivating the memory, by trauma and perceived culpability, by social conformity, and by talking about the event. However, people evaluating the statements are often not aware of these issues. On Crossair Flight 498, there was only a post-impact fire even though witnesses say they saw fire before the crash.
Continuing down the path of possible mechanical failures, the aircraft that was Flight 498 had a history of uncontrolled flap movements. As we have mentioned in other episodes, the flaps extend from the backs of the wings during takeoff to increase lift. If flaps do not extend properly, it makes the plane hard to control. And, if one flap extends more rapidly than the other one, it can cause the plane to roll to one side as one wing would have more lift and one wing would have more drag. In the preceding 18 months, more than 20 complaints have come in from various flight crews about the flaps on this aircraft. This revelation raises alarms with investigators as this number of complaints is highly unusual. Unfortunately, while the flaps have been pulled from the wreckage, they are too damaged by the impact to yield any useful information for investigators. Investigators will need to listen to the flight’s recorders.
Thankfully, both flight recorders are found just two days after the crash: the flight data recorder, which records important flight parameters and conveys information about the operational performance of the flight, and the cockpit voice recorder which records all conversation in the cockpit and with air traffic control.
Using data from the flight data recorder, the investigators create a simulation of the flight path traveled by Flight 498 based on all the flight’s operating parameters. What they find is simple: there are no flap or other aircraft malfunctions happening.
The other part of this story now comes into sharp focus: Captain Gruzin simply turned right instead of left and then fatally lost control of the aircraft. These findings baffle investigators as they next must search for the answer to why and how this could have happened. This leads them to focus on what was happening within the cockpit, both from a flight control perspective and also from a crew resource management perspective.
Investigators Rule Out Cell Phone Interference as Possible Cause of Crossair Flight 498 Crash
On the CVR, while the Captain is giving out a command to the First Officer, investigators hear a noise in the background being picked up by the recorder. It sounds to them like cell phone interference. Back in the year 2000, when this crash happened, mobile phones were a real potential threat to aviation.
During a 2003 study published Friday by the U.K. Civil Aviation Authority (or CAA), a series of tests exposing a set of aircraft avionic systems to simulated cell phone transmissions revealed various adverse effects on the equipment's performance. From March 1996 to December 2002, the CAA recorded 35 aircraft safety-related incidents that were linked to cell phones. The reported interference incidents included interrupted communications due to noise in the flight crew's headphones, according to the study.
Boeing also investigated several cases in the 1990s where aircraft crews reported that laptop computers or gaming devices caused autopilot disconnects, uncommanded airplane rolls or instrument display malfunctions. However, the aircraft manufacturer was never able to replicate the reported anomalies in lab tests.
While many in aviation believe that the threat of mobile phones is becoming more obsolete, here is what we know happens. When a phone is in use, it transmits a signal to the mobile phone tower, and as it does, it can cause interference, which is picked up and recorded as a buzz by the plane’s recorder. The same interference was picked up on the CVR for Flight 498, though as it never will do, the recorder did not show that this mobile phone interference caused any malfunctions that would cause flight control problems. One of the final possibilities that investigators explore is, did the cell phone interference somehow affect the flight displays, especially those that convey the artificial horizon, since the crew was flying using their instruments due to it being a dark evening.
Their simulation finds nothing to support that theory, and, records from passengers’ cell phones show that all usage ended before the flight took off. Other than the interference picked up by the CVR, mobile phone interference had no other effect on Flight 498.
Investigators Find Tranquilizers in Bag of Crossair 498 Captain Gruzin
Next, an additional piece of physical evidence makes investigators question what was happening in the cockpit. They find the Captain’s personal bag, which was thrown from the plane when it crashed, and the contents of the bag shocks investigators: they find a partial pack of pills which are a type of benzodiazepine drug known as phenazepam, which is a powerful sedative similar to valium. They’re basically on par with tranquilizers. The drug is commonly used to treat neurotic disorders, alcohol abuse disorder, epilepsy, sleep disorder, anxiety disorder, and in combination with haloperidol, to treat schizophrenia.
Investigators travel to Moldova, where the Captain is from, to get more information from his family about why he was taking the drugs. Captain Gruzin’s wife reports that her husband was very stressed because he was actually living in Switzerland most of the year away from his family and sending money home to them. The autopsy finds the presence of this same drug in Captain Gruzin’s muscle tissue, but there is not enough of the drug present to prove that he was in fact impaired while flying that day. Additionally, when investigators listen to the cockpit voice recorder (or CVR) for clues to the Captain’s alertness and lucidity, they find no evidence that he was impaired as demonstrated by his actions and his speech patterns. Investigators conclude that any state of impairedness would not have helped improve the situation, so they can only assume it did, somehow, make the worsen the situation.
Nothing, so far, has emerged that would lead investigators to find a specific probable cause. That is, until they explore how the Captain and First Officer were flying the plane and communicating with one another.
Opposing Cockpit Design Leads to Crew Confusion in Flight 498 Crash
As we have mentioned earlier, the day of the crash was a cloudy, dark, drizzly winter evening. The pilots would have needed to fly using their instruments since the natural horizon would have been obscured. But, mysteriously, neither the captain nor the first officer noticed that the plane was going in the wrong direction and then was banking at such an angle that the plane went into a spiral dive. The reason for this comes down to cockpit design.
Investigators examine the way that the flight instruments were showing the position of the aircraft in the last moment of the flight. They assess the cockpit design for any issues that may have led to the Captain not understanding that the plane was banking in the wrong direction.
The cockpit display system in the Saab 340B was designed so that if the plane went into an abnormal bank or pitch angle, the display would automatically remove unnecessary information to make the recovery easier for the pilots. It is clear based on the flight data recorder (or FDR) that at the time of the banking, the instruments were working properly. But, investigators deduce that Captain Gruzin did not understand them. What investigators wonder is, how could someone with Gruzin’s credentials not be able to tell the difference between left and right?
Captain Gruzin learned to fly in Russia, and at the time, Crossair was known for recruiting many pilots from the former Soviet Union. While nothing about either of the pilots’ previous performance records hold the answer, Russian investigators, helping the Swiss investigators, reveal something troubling: they are aware of a recent cluster of accidents where Russian-trained pilots became confused by the instrument that shows the artificial horizon, a fact which is not well-known in Western aviation. This indicator is crucial for pilots in bad weather, nighttime, and high altitude when the actual ground cannot be seen. Crossair Flight 498 took off in the dark, so, naturally, the pilots had to rely on the artificial horizon to make the turn as instructed by air traffic control.
And here is what the Swiss team uncovers. Pilots from the Soviet Union were trained to use an artificial horizon that looked very different than the one used in the West because Russian planes and Western planes have very different design philosophies. In particular, the artificial horizon is designed completely in opposition.
In the West, the airplane icon remains stable as the background and horizon moves. The Soviet aircraft horizon works in the opposite way: the airplane icon moves, the background stays stable, and the horizon is fixed in place. A left turn on a Soviet display looks a lot like a right turn on a Western display. As countries in the West began to buy more Eastern European planes, that confusion became deadly. In fact, there were fifteen crashes involving spiral dives that many suspected were caused by pilot confusion.
Crossair 498 Captain Used Wrong Training, Failed to Engage Autopilot
Investigators believe they have uncovered the probable cause of the accident. Stressed and possibly under the influence, Captain Gruzin may have fallen back on what he learned when he first learned to fly. As contained in the technical analysis of the air accident report, the Captain’s growing confusion led him to resort to problem-solving models learned at an earlier time. The confusion over the aircraft’s attitude and the corrections that needed to be made in the final moments of the flight were reinforced by the fact that the Captain had been trained on Russian instruments, and that as a result, he may have retrieved and applied a reaction pattern from that period. It must be added that he had had no opportunity to be trained in any other pattern of behavior. In his confusion, he was convinced he was flying in a steep left turn instead of a right turn.
To make matters worse in this crash, Russian pilots also do more hand flying because Russians think one should hand fly as long as possible to prove you really can fly. Autopilot can fly the plane even if both pilots have other tasks to do. Captain Gruzin was flying manually, and the autopilot was not engaged. If he had engaged autopilot right after takeoff, the accident likely would never have happened.
And instructions from ATC added to the problem. The controller, once he noticed the plane turning right instead of left said, “498 confirm you’re turning left”. ATC should have said, “I see you in a right turn, please turn left.” Captain Gruzin was trying to level a plane that he thought was going left when his actions actually put the plane in a deadly spiral dive because it was going right.
First Officer Unable to See Critical Flight Instruments in Time to Prevent Crossair 498 Crash
But Captain Gruzin was not the only one in the cockpit. What was First Officer Kolesár doing?
His job was to monitor the instruments, but doing so was an immense challenge due to the awkward cockpit design, which made it difficult for First Officer Kolesár to see what was going on. There was only so much room in the small cockpit for all the instruments and on this particular aircraft, it was designed in a way that is not well organized for a pilot.
The tasks the first officer had to perform were demanding and required great concentration. The instruments and controls he had to operate in this context were not in the same field of view as the flight attitude instruments. As explained in the official accident report, the division of labor in the take-off phase was always the same at Crossair. In particular, take-off was always undertaken by the Captain. Therefore, the first officer had little experience of controlling the aircraft in this takeoff phase and of any possible difficulties which might arise in the process. It is conceivable that the first officer of the aircraft involved in the accident was paying little attention to the flight path being flown by the commander and to the attitude.
First Officer Kolesár would be performing tasks during the take off and climb with his head down or up and while looking away from the horizon display. This fact was echoed by many the experience of many other First Officers. By the time First Officer Kolesár saw the plane was going in the wrong direction, the plane was already in a steep right bank. And to complicate things even further, the First Officer input the data into the system that listed their flight path, but he omitted the left turn from the sequence. And without defining the turn direction, the flight director (the main flight system on the plane) commands a right turn.
Investigators found when they observed other pilots during a simulation of this same flight that it took pilots between 4 and 18 seconds for them to figure out what the plane was doing and what action was needed to recover from it. And that was all the time it took for the plane to crash once it banked too far right.
Crossair 498 Pilots Struggle to Communicate During Emergency
And the communication in the cockpit wasn’t great. The First Officer was shouting at the Captain, “no left left!” But the Captain did not understand what the First Officer was trying to tell him because he was sure he was already turning left, not right. Their English was basically aviation English. It is hard in this high-pressure situation to communicate fluently and effectively. This fact, together with the information from the biography of the pilots, make it possible to conclude that there was an atmosphere in which little spontaneous communication was possible. The two pilots were able to converse only in a foreign language, English, and in addition this language was full of the highly standardized expressions of technical aviation. It must remain open whether this circumstance left any space at all for spontaneous communication. It must be stated that under such conditions a spontaneous reaction to an unexpected perception, such as an exclamation or an expletive, would tend to remain suppressed. A common linguistic pattern appropriate to this abnormal attitude – such as that for the communication of technical failures, for example – was obviously not available to the crew.
Investigators Find Probable Causes of Crossair 498 Crash
Ultimately, there are multiple factors that led to the crash of Crossair Flight 498: the language barrier that existed between the two pilots when communicating in an emergency situation, the confusion caused by the cockpit displaying the plane’s attitude, the Captain’s being potentially under the influence, the First Officer not being able to see clearly enough the flight displays that would have told him immediately the plane was banking to the right, and failure to engage the autopilot after takeoff.
Crossair 498 Tragedy Leads to Better Training, Mandatory Autopilot Engagement
Crossair Flight 498 has a straightforward legacy. Following the crash, at Crossair, Soviet pilots got 3 months of extra training and language testing. All Swiss crews are now required to engage autopilot after takeoff to be able to pay attention to the flight’s progress in real-time.
A memorial site was established after the crash, with a plaque on a large boulder facing the direction of the crashed airplane. On the plaque are inscribed all 10 victims’ names.
And THAT is the story of Crossair Flight 498.
Show Notes:In this episode we talk about mysterious aches and pains that seem to pop up as you get older (and how even Will Smith says he's in the worst shape of his life after quarantine). We also talk about the joys of connecting- or reconnecting- with people as we shift back toward spending time with friends in person again.
Credits:Written and produced by: Shelly Price and Stephanie Hubka
Directed and engineered at: Snow Monster Studios
Sound editor: Stephanie Hubka
Producer: Adam Hubka
Music by: Mike Dunn