Awakened to a Nightmare: The crash of Air India Express flight 812

Firefighters battle the flames after the crash of Air India Express flight 812. Image source: UPI

On the 22nd of May 2010, an Air India Express Boeing 737 arriving from Dubai landed long at Mangalore Airport in Karnataka. As the plane hurtled toward the end of the runway, the captain panicked and attempted to take off again, but it was too late. The 737 struck an ILS antenna, crashed through the airport perimeter fence, and plunged 55 meters down a forested hillside, where it broke into three pieces and burst into flames. Of the 166 people on board, 158 perished in the crash and the fire that followed, while eight badly injured survivors managed to escape with their lives. As Indians clamored for answers, investigators began to reveal shocking details of the minutes and hours leading up to the disaster. The approach was much too high. The plane could have stopped on the runway if the pilots had used maximum braking power. The first officer had repeatedly told the captain to go around, but was ignored. And for at least 110 minutes of the flight, stretching all the way until the initial descent toward the airport, the captain had been asleep at the wheel. With widespread anger mounting over this apparently reckless disregard for safety, investigators took the opportunity to issue a sweeping set of recommendations that they hoped would revolutionize aviation safety in India.

VT-AXV, the aircraft involved in the accident. Image source: Sean d’Silva

Air India Express is a wholly-owned low cost subsidiary of India’s flag carrier, Air India. Launched in 2005, the airline began with three Boeing 737–800s and quickly grew that number to more than 20. Most of the high level management at Air India Express was deputized from Air India, and the parent airline often sent newly minted captains to temporary jobs at Air India Express before promoting them to command the wide body airliners flown by Air India. A shortage of qualified captains in the domestic market meant that both airlines often had to hire them from abroad, and conflict between foreign captains and Indian first officers looking to upgrade was commonplace.

The route of Air India Express flight 812. Map source: Google

It was one such mismatched crew that was scheduled to perform a round trip from Mangalore to Dubai and back again on the 21st-22nd of May 2010. In command was Captain Zlatko Glušica, a Serbian expat who had just returned to India after two weeks back home on leave. Colleagues described him as friendly and professional, but he was also hard-headed and tended to believe he was always right. He was also secretly looking for a new employer. Unbeknownst to his colleagues, he had been making overtures to Turkish Airlines, and he had several Turkish banknotes hidden away in his pocket when he showed up to work that night.

Joining him in the cockpit was First Officer Harbinder Ahluwalia, an Indian national, who was known for being meticulous, knowledgeable, and a stickler for the rules. In the past, he had lodged complaints with Air India Express management when foreign captains violated standard operating procedures or used incorrect crew resource management techniques. Nevertheless, he preferred to avoid conflict face-to-face, and usually complained through official channels after the fact.

Glušica and Ahluwalia flew the outbound flight from Mangalore to Dubai without incident, and after a quick turnaround on the ground in the United Arab Emirates, they prepared for the return journey. Once the 160 passengers and 6 crew had boarded the Boeing 737, Air India Express flight 812 taxied to the runway and took off at 1:06 a.m. local time.

The known history of the flight starts approximately 84 minutes later, at 4:00 am. Indian standard time, where the cockpit voice recording begins. With the plane in steady cruise flight interrupted only by the occasional radio call, Captain Glušica had apparently taken the opportunity to catch up on sleep and lay snoring in his seat. First Officer Ahluwalia occasionally spoke with air traffic control or with the cabin crew, but otherwise, all was quiet. Glušica was still sleeping at 5:32 when Ahluwalia made contact with Mangalore air traffic control and received weather reports, runway information, and preliminary descent instructions.

At 5:41, after concluding the conversation with ATC, Ahluwalia woke up his captain and gave him a rough briefing on the conditions ahead. He seemed concerned by one problem in particular: the lack of radar at Mangalore. Mangalore Airport normally has radar, but a mechanical failure had taken it out of service two days earlier, and it wouldn’t be back up until later that week. As a result, air traffic controllers were routing incoming planes along a slightly different path than usual: instead of beginning the descent 240km from the airport as they were accustomed to, they would start descending at 148km. Apparently uncertain as to how this might affect their plans, Ahluwalia said to Glušica, “…Radar not available, but I, uh, don’t know what to do.” What Glušica said in response is unknown, as he had not yet put on his headset, which contained the recording mic.

The change in the descent pattern due to the unserviceable radar was the first link in a rapidly escalating sequence of events. Ahluwalia and Glušica failed to perform a normal approach briefing, during which they would have gone over the procedures in detail. This was especially critical given that Ahluwalia did not know the correct procedure to follow when his initial descent request was denied. With Glušica still getting himself ready after his extended nap, Ahluwalia began the descent at 148km from Mangalore without confirming what descent rate they would need to intercept the glide slope from that distance. Mangalore, like many airports, uses an Instrument Landing System (ILS), which emits a signal that an airplane’s flight computers can follow all the way down to the runway. This signal is known as the glide slope. The plane must be at a particular altitude when it lines up with the runway in order to correctly “intercept” the glide slope, and flight 812 was on track to miss it unless Ahluwalia increased their descent rate.

A basic diagram of a glide slope. Image source: Flight Mechanic

Mangalore Airport, situated on India’s mountainous southwest coast, is a so-called “tabletop airport” — that is, it’s built on the leveled top of a hill with large drops on all sides. It has little margin for error, and as a result, approaches to Mangalore must always be flown by the captain. As soon as he was ready to do so, Glušica took over, despite the fact that he was still emerging from the post-sleep stupor. He apparently didn’t notice that the plane was too high until 5:59, at which point they were descending through 8,500 feet. To try to increase the aircraft’s descent rate, he lowered the landing gear and deployed the speed brakes, which reduce the lift generated by the wings. But even this was ineffective: as flight 812 lined up with the runway, it was twice as high as it should have been. In fact, they were so far outside the normal descent profile that they managed to lock onto a “false glide slope.” The signal emitted by the ILS reflects off the ground and off the equipment itself, creating several copies of the glide slope at progressively steeper angles. Normally, an aircraft on approach won’t pass anywhere near these false glide slopes, but flight 812 wasn’t flying a normal approach. The plane locked onto a false glide slope six degrees higher than the real one, resulting in an excessive descent rate greater than 3,000 feet per minute. Attempting a landing at such a descent rate would be borderline suicidal.

Several false glide slopes lurk above the real glide slope. Image source: Aviation Dictionary

About 3 minutes later, Captain Glušica again exclaimed, “It’s too high!”

By now it had also become clear to First Officer Ahluwalia that something was wrong. “Runway straight down!” he said.

For the first time, Glušica seemed to realize just how big the problem was. “Oh my god!” he said. “Okay… oops.”

At this point, both their airspeed and their descent rate were in excess of the limits for this approach. This meant that the approach was unstabilized, and standard operating procedures called for the crew to go around and try again. Ahluwalia knew this, and he expected Glušica to comply. But instead of calling for a go around, Glušica disconnected the autopilot and tried to finish the landing manually.

“Go around?” Ahluwalia asked, confused by his captain’s deviation from this basic procedure.

“Wrong localizer glide path,” said Glušica, explaining that they had intercepted a false glide slope.

Flight 812 was now descending so quickly that the ground proximity warning system (EGPWS) activated, calling out, “SINK RATE! SINK RATE!”

“Go around, Captain! Unstabilized!” Ahluwalia exclaimed.

The air traffic controller suddenly broke in over the radio and asked, “Express India eight one two, confirm established [on the glide slope]?”

“Affirmative, affirmative,” said Glušica, even though he knew this was false. The controller replied that they were cleared to land, even as the EGPWS continued to call out, “SINK RATE! PULL UP! PULL UP!”

The conversations of the pilots overlaid onto a diagram of the aircraft’s position. The diagonal blue line represents the correct glide slope and the red line indicates the position of the aircraft. Image source: the DGCA

Air India Express flight 812 overflew the runway threshold 20 knots too fast and four times higher than normal. As Glušica tried desperately to plant the plane on the runway, the automated voice continued its rapid-fire speech: “Forty. Thirty. Twenty. Ten.”

One rear wheel hit the runway and the plane bounced back into the air. “Go around, captain!” said Ahluwalia.

Glušica finally managed to get the wheels on the ground 1,585 meters down the 2,450-meter runway, far later than normal. He activated reverse thrust and the autobrakes in an effort to slow down, but it was immediately clear that this would be insufficient.

Where flight 812 touched down in relation to the normal touchdown zone. Map source: Google

“We don’t have runway left,” said Ahluwalia. At this point, they were going off the end no matter what they did.

“Oh my god!” Glušica screamed. With the runway end rapidly approaching, he finally decided to attempt a go-around, but it was much too late: standard operating procedures advise that a go-around after deployment of the thrust reversers is strictly prohibited. But he tried anyway, letting off the brakes and throwing the engines from reverse to full forward thrust. Just as the engines began to spool up, they ran out of room. Flight 812 rumbled off the paved runway and into the runway end safety area, a gravel pit meant to stop runaway aircraft from rolling off the edge of the plateau. But even this was insufficient to stop the speeding 737.

An artistic rendering of the moment flight 812 plunged over the edge. (Own work)

As the plane hurtled across the downward-sloping overrun area, the right wing smashed into the concrete support framework that held up the instrument landing system, collapsing the structure and tearing off the wingtip. Spilled fuel ignited, leaving a trail of fire behind the aircraft as it careened over the edge. Air India Express flight 812 fell 55 meters straight down into the gorge, clearing a road before slamming into a steep, forested hillside. The cockpit voice recorder captured a scream, the blare of a “BANK ANGLE” warning, and then silence. The plane split into three pieces on impact and burst into flames, sending a wall of fire and smoke tearing through the cabin almost immediately. Of the 166 people on board, around half survived the initial crash, but for most there was no opportunity to escape the inferno that followed. Dozens of people burned alive in the wreckage as they struggled to undo their seatbelts and find their way out of the mangled fuselage. Precious few made it. Seven men seated just aft of the wings managed to climb out through a break in the fuselage, some sustaining burns in the process, while a woman in row 7 managed to climb back up the aisle and got out the same way.

Flames erupt from the crash site, seen from across the valley. Image source: NDTV

Upon realizing that the plane had overrun the runway, airport fire crews scrambled to respond. The first fire truck on scene drove down to the end of runway and found a large section of the plane’s wing on the ground, burning. The firefighters attempted to spray water down onto the main section of the fuselage, but it was too far away, so they extinguished the spot fires on the rim of the gorge instead. Meanwhile, several more fire trucks attempted to reach the crash site, but the narrow roads surrounding the airport proved difficult to navigate in such large vehicles. To make matters worse, onlookers had already begun to crowd the roadway, forcing the fire trucks to push through them to reach the plane. By the time they arrived, approximately five minutes after the crash, the fire had already consumed the entire aircraft. While fire crews battled the flames and ambulances rushed the survivors to hospital, rescuers mounted a frantic search for more survivors. Although they did find a young girl showing signs of life, she died before reaching the hospital, and no other survivors could be found. In all, 158 people died, including all six crew, while only eight passengers lived to tell the tale.

Seating locations of the survivors, as well as those who died by various causes. Image source: the DGCA

Medical examinations later showed that 84 people had died primarily due to impact forces, or would have shortly died had they not burned to death first. A further 73 people died solely due to burns, and one died of smoke inhalation. From their hospital beds, survivors corroborated these findings, reporting that in the moments after the crash, they had heard many people shouting and screaming for help. Unfortunately, there was nothing anyone could have done to save them.

Within hours, investigators from India’s Directorate General of Civil Aviation (DGCA) arrived on the scene and recovered the aircraft’s black boxes. In Washington D.C. some days later, Indian and American investigators opened the flight recorders and downloaded the data. Investigators were left bewildered from the very beginning of the cockpit voice recording. The first 110 minutes of the tape consisted of Captain Glušica sleeping, making this the first time that the US National Transportation Safety Board had ever encountered snoring on a CVR. The fact that Glušica was asleep until just 23 minutes before the crash surely contributed — but how?

People gathered around the crash site as firefighters finished dousing the flames. Image source: AP

Everyone is familiar with the sluggishness that one feels immediately after waking from a deep sleep. Science, as it turns out, has a name for this: sleep inertia. The period of sleep inertia can last anywhere from 20 minutes to several hours depending on the person and the circumstances, but it is especially acute when a person is awakened during their window of circadian low, the period of the night during which the body expects to be asleep. The entire flight occurred during both pilots’ window of circadian low, which not only contributed to Glušica’s apparently overwhelming desire to sleep, but also to his impairment after waking up. And not only was Glušica evidently suffering from sleep inertia, evidence indicated that he might have had a cold as well. His family reported that he had a sore throat before leaving Serbia several days earlier, and he could be heard coughing and clearing his throat throughout the descent to the airport. If he in fact had come down with a cold, it could have made his fatigue even worse. And there was evidence that First Officer Ahluwalia was fatigued as well: the cockpit voice recorder capturing him yawning on multiple occasions.

The shattered remnants of the aircraft’s fuselage. Image source: Neil Pinto

Fatigue and sleep inertia can result in a lack of perceptiveness, automatic behavior, flawed logic, and failure to grasp the severity of a problem. Captain Glušica displayed all of these symptoms during the descent to the airport, potentially explaining why he didn’t recognize the unstabilized nature of the approach and initiate a go-around. But First Officer Ahluwalia was supposedly obsessed with following standard operating procedures, so why didn’t he react more forcefully? He also committed several violations himself, including failing to conduct a proper approach briefing. This can be partially pinned on fatigue, but he was also disinclined to call out violations to a captain’s face — he preferred to lodge formal complaints through official channels. Faced with a captain known for an “always right” attitude, he might have wanted to file a report after landing rather than trying to cross him right then. Once he began calling for a go-around, he could have assumed command and performed it himself — but that would be a major leap for a first officer, especially when landing at an airport with special rules that required the captain to fly the approach, which might have led him to believe he lacked the authority to take control.

After the fire was put out, only the extremities of the plane were recognizable. Image source: the Bureau of Aircraft Accidents Archives

Another factor that might have influenced Captain Glušica’s failure to go around was the experience of other captains who had done so in the past. Fresh in his mind was the case of an Air India Express pilot, also a foreigner, who performed a go-around at another airport. ATC pressured him for an explanation for his actions and he was questioned by the media after landing. Furthermore, Glušica himself had a bad experience after a hard landing some months before. The airline had sent him to “Flight Safety Counseling,” during which he received various reprimands for his performance. He felt that this was unjust because the first officer had actually been the one flying during the hard landing. In addition, many pilots reported that the constructiveness of Flight Safety Counseling varied from moderately helpful to downright humiliating. It didn’t help that when a pilot had counseling on his or her schedule, all the other pilots could see it. By the time Glušica made his decision not to go around, he probably would have been eligible for Flight Safety Counseling no matter what he did, but the possibility surely would have been in the back of his mind as something he wanted to avoid, and it could have contributed to his desperate attempt to stick the landing.

Firefighters battle the flames at the height of the inferno. Image source: UPI

However, even after the plane touched down two thirds of the way down the runway, disaster was not yet ensured. The theoretical minimum stopping distance for a Boeing 737–800 in this configuration was such that it could have stopped on the runway if maximum manual braking and reverse thrust had been applied immediately. Even assuming an imperfect reaction from the pilots, the plane could have been stopped in the overrun area. But as it turned out, Captain Glušica initially left braking up to the autobrakes, which were set to a moderate setting that didn’t allow them to apply maximum braking power. After several seconds, Glušica briefly applied full manual braking, but then cancelled it when he made the decision to try to take off again. More than anything it was this indecisiveness that resulted in such a severe crash. There wasn’t enough time left to cancel reverse thrust, apply max power, and build up enough speed to take off again. Instead, all he managed to do was increase the speed of the plane before it fell over the edge, resulting in a longer drop, a harder impact, and more fatalities. This is why standard operating procedures explicitly prohibit attempting a go-around after applying reverse thrust.

Wreckage of the 737 is removed using a backhoe. Image source: the Bureau of Aircraft Accidents Archives

Although the pilots made serious mistakes, as investigators examined the organizational structure of Air India Express it became clear that the airline was not creating an environment conducive to safety. None of its chief position-holders for training, operations, and flight safety had any formal flight safety training, nor were they qualified on the Boeing 737–800, the only aircraft operated by Air India Express. They had all been deputized by Air India on a short-term basis and had little connection to the company they were overseeing. Furthermore, Air India’s practice of sending newly promoted captains to gain experience at Air India Express before upgrading to wide body jets placed an excessive training load on the smaller airline. Air India Express was forced to constantly train pilots who would then move on to Air India, taxing its training capabilities to the limit. This also caused tension between employees as Air India Express first officers seeking promotion to captain would be continuously passed over in favor of temporary captains cycling through from Air India. First officers like Harbinder Ahluwalia had a rocky relationship with many Air India Express captains, which could have contributed to his ineffective communication with Captain Glušica. And on top of all this, Air India Express lacked a computerized scheduling system, which often left pilots in the dark about their schedules until the last minute. This made it harder for them to plan personal activities, including sleep, and caused increased levels of stress.

Looking out over the place where the plane went over the edge. The collapsed ILS platform and part of the severed wing can be seen on the right. Image source: the DGCA

The DGCA also identified deficiencies with the airport itself that contributed to the severity of the accident. Although there was a sand pit at the end of the runway, it hadn’t been properly maintained, allowing the sand to become compacted and infested with plants. This reduced its ability to slow the plane. The sand pit also sloped downward, which the DGCA felt was unsafe. And finally, there was an infrangible concrete support structure for the ILS sitting in the middle of the sand pit, which breached the fuel tanks and jump-started the fire that took so many lives. The DGCA believed that the airport could solve all of these problems by elevating the sand pit until it was level with the runway, which would remove the downward slope and cover up the concrete support structure.

Wreckage of the 737 is removed using a backhoe. Image source: the Bureau of Aircraft Accidents Archives

Taking all of these factors together, it was clear to the DGCA that major improvements were needed to ensure the safety of aviation in India. In its final report, it issued a lengthy list of recommendations intended to address the problems uncovered during the investigation. It asked that Air India Express be operated as a separate entity from Air India; calibrate its growth rate so as not to exceed its ability to build up safety infrastructure; appoint new heads of operations, training, and flight safety who are qualified on the Boeing 737–800; create a computerized scheduling system; ensure that flight safety counseling is non-punitive and used only when necessary; foster a common culture and understanding among its diverse assortment of pilots; and provide better cockpit resource management training. To the Airports Authority of India, it recommended that runway overrun areas be made not to slope downward; that structures in runway overrun areas be made frangible; that Mangalore Airport maintain its runway end safety area properly; that airports including Mangalore consider installing enhanced materials arresting systems, which are more effective than sand pits; that Mangalore Airport install “distance to go” markers along its runways; that Mangalore Airport purchase some smaller firefighting vehicles that can navigate nearby roads; and that airport firefighters receive simulator training. And the investigators recommended that the DGCA itself update flight duty time limits, mandate that airlines develop fatigue risk management systems, regulate when and how pilots can sleep during flight, clarify the authority of a first officer to initiate a go-around if the captain does not, require airline executives to undergo safety management training, and begin publishing a flight safety periodical.

An Air India Express Boeing 737–800 takes to the skies. Image source: The Flight Channel

However, the investigators’ final recommendation was perhaps the most important. In its report, the DGCA called for the creation of an independent aircraft accident investigation agency modeled after the NTSB in the United States. In the past, accident investigations in India had been carried out by the DGCA, which was also the regulator, creating a long-running conflict of interest. An independent agency could permanently solve this problem. As a direct result of this request, the Indian government created the Civil Aviation Authority of India, a brand new agency whose sole mission is to investigate aircraft accidents and recommend safety actions. At the same time, the DGCA for the first time announced that it would release all its accident reports publicly so that anyone could learn the safety lessons contained therein. However, implementation of some of the other recommendations has been spotty. For example, the design of the runway overrun area at Mangalore Airport has not changed since the crash, meaning that a repeat accident cannot be ruled out. And yet there has been a tangible improvement in India’s aviation safety. In fact, in the 10 years since the crash of Air India Express flight 812, there has not been another major airline accident in India.

Author’s note: in August 2020, another Air India Express 737 ran off the end of the runway in Kozhikode, killing 21 of the 190 people on board. In light of this occurrence, any suggestion in the original article that the situation had improved ought to be taken with a grain of salt.

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Analyzer of plane crashes and author of upcoming book (soon™). Contact me via @Admiral_Cloudberg on Reddit or by email at kylanddempsey@gmail.com.