WION Exclusive | Was it a data error, miscommunication, or malfunction? Former pilot and training captain weighs in on possible reasons

It was meant to be a routine flight. Instead, it became one of the most haunting tragedies in recent Indian aviation memory. Shortly after take-off from Ahmedabad airport, Air India flight AI171 plunged from the skies, leaving behind wreckage, grief—and a trail of unanswered questions.

The pilot’s last words were stark and chilling: “Mayday, Mayday, Mayday.” That was all. No follow-up. No elaboration. Silence, then impact.

As investigators sift through the data and debris, a broader aviation community is asking: What happened in those final seconds? Could the crash have been avoided? And what does it tell us about the pressure’s pilots face when machines malfunction and margins vanish?

To make sense of the tragedy, WION spoke exclusively to former captain and training captain SK Pillai, with decades of experience in cockpit emergencies and pilot instruction. The former captain discusses and explains possible factors that can lead to disasters like these.

His breakdown offers a window into a world where decisions are made faster than thought—and where a single misstep can turn an aircraft into a falling object.

The final transmission: ‘Mayday’ and then nothing

According to air traffic control logs, the pilot of the flight managed to transmit just one short distress call. It was formal and urgent: “Mayday, Mayday, Mayday”—the internationally recognised radio transmission for emergency situations.

But what stood out to experts wasn’t just what was said—it was what wasn’t. “A Mayday call means the pilot is facing a life-threatening emergency,” says Pillai. “Normally, pilots follow this with details of their situation and intentions, but in this case, there was hardly any time.”

The lack of a follow-up message strongly suggests the pilot was already overwhelmed—perhaps battling for control, diagnosing a problem, or trying to manage the plane’s trajectory in those final moments.

“In an emergency, your first duty is to fly the airplane,” Pillai explains. “You have to get control of the aircraft, see where it’s going, and determine your desired trajectory. Communication comes later.”

Aviation’s central mystery: Why didn’t the plane climb?

The plane, according to radar data, reached just about 625 feet above the ground before beginning a fatal descent. This raises one of the most baffling questions in the investigation: Why couldn’t the aircraft climb?

While structural failure or sabotage has not been ruled out, Pillai in his personal opinion feels there are possibilities of errors while loading data. “The probability of both engines failing simultaneously is one in many millions,” he says.

He noted that video footage taken just before the crash showed no signs of smoke or fire, making a bird strike unlikely.

The hidden threat: Incorrect take-off data

Every pilot, before take-off, inputs crucial parameters into the flight management system—details like aircraft weight, runway condition, temperature, and wind speed. From this, the aircraft computes three critical speeds.

If these calculations are wrong—especially weight—the result can be devastating. “If incorrect data is entered—for example, underestimating the aircraft’s weight—the computer may set insufficient thrust, leading to a sluggish take-off or inability to climb,” explains Pillai.

He references the 2009 near-disaster of an Emirates flight 407, from Auckland to Dubai with a stopover in Melbourne.

The Australian Transport Safety Bureau (ATSB) led the investigation into the accident,

focusing on three key questions: How the first officer came to enter an incorrect aircraft weight, why the error went undetected prior to take-off, and why the flight crew failed to notice the unusually slow acceleration until nearly the entire 3.6-kilometre (12,000-foot) runway had been used.

“If the computer thinks the plane is lighter than it actually is, it won’t command enough power. You’ll lift off sluggishly, maybe not at all.”

Human factors: When team dynamics go awry

The cockpit is a place of hierarchy—but also of shared responsibility. A seasoned captain working with a less experienced first officer may create an imbalance that affects safety.

“An experienced pilot can multitask and set a fast pace, but if the co-pilot is less experienced and fails to double-check, errors can creep in,” Pillai notes.

In critical moments, a failure to cross-verify aircraft weight, flap settings can reduce acceleration and climb rate—eating into safety margins rapidly. Failure to cross check, can lead to an errors in calculating the take off run required and climb performance.

“If the weight is incorrect, the plane may not accelerate or climb as expected, using up more runway and reducing safety margins,” he said.

Landing gear, flaps—and the danger of mistakes

Among the anomalies being examined is the suggestion that the landing gear was never retracted. Normally, gear-up selection happens shortly after take-off.

“After reaching 35 to 50 feet, you select the landing gear up,” says Pillai. “If this isn’t done, it could be due to preoccupation with an emergency—or by mistake moving the flaps lever instead of the gear lever.”

This isn’t just theoretical. He recounts a past tragedy caused by a similar mistake where the flap lever was moved instead of the gear lever, thereby reducing speed and increasing drag

How simulators keep pilots prepared for the worst

Modern commercial aviation is built on precision, preparedness, and constant practice—especially for those in the cockpit. Pillai says that no matter how experienced a pilot is, continuous training is non-negotiable.

“Every pilot, right down to the time he retires—whether he’s a seasoned training captain with 30,000 hours or a newcomer with just 500—has to undergo mandatory simulator training every six months.”

These aren't just routine refreshers. The simulator sessions replicate a wide range of

emergency scenarios: engine failures, hydraulic losses, electrical faults, bird strikes, and even complex weather conditions.

“Almost any emergency that you can think of—that can happen on an airplane—is simulated and practiced. Because in reality, many pilots may never experience a single major emergency in their entire career,” he explains.

Despite that rarity, preparedness is key. That's why proficiency checks are held after every simulator session. Pilots must pass these checks to keep their licenses valid and remain eligible to fly.

“It’s not optional. If a pilot doesn’t clear the check, they don’t go back to line flying,” the former captain stresses.

Beyond simulator evaluations, pilots are subject to other regular in-flight assessments such as route checks. “Practically every three months, there’s some form of check or clearance. The system is designed to ensure pilots stay sharp—not just technically, but also in decision-making under pressure."