Last week, a tragedy was prevented on Indian skies when two IndiGo planes averted a mid-air collision. It was a narrow escape for the 330 passengers on board the two aircraft.
This was the fourth such incident involving IndiGo aircraft in the last one year. Other airlines, including SpiceJet and Vistara, have also been involved in similar incidents where two planes came too close to each other.
Experts, though, say the rate of such events — a near-miss, called air proximity, in aviation jargon — is much higher than what is being reported, or disclosed.
“There is at least one such event happening every day on Indian skies. But these are not reported,” says Yeshwanth Shenoy, a lawyer and aviation safety activist who has been highlighting serious lapses in Indian skies.
“It’s a collective failure of regulator DGCA, Airports Authority of India (which manages the Air Traffic Control centres) and the airlines,” says Shenoy.
In others words, the dangerous turn of events is the outcome of tired pilots, insufficient infrastructure and lax regulation.
Adds Mohan Ranganathan, a former pilot and aviation expert, “It is a case of trying to push your luck too much.”
The two IndiGo airlines had come within 200 feet of each other, prompting the Traffic Collision Avoidance System (TCAS) alert to go off.
The system works this way.
An aircraft’s cockpit has many monitors, including one that shows other aircraft in the vicinity. Each aircraft is represented by a plane-like symbol.
When the neighbouring aircraft is at a safe distance, the symbol is white. It turns to yellow when an “intruding aircraft” comes within 48 seconds and the system lets out an audio alert to grab the pilot’s attention.
If there is no action from the pilot, and if the intruder is still on collision course and within 10 seconds of the aircraft, then the symbol turns red and an alarm goes out asking the pilot to either climb or descend.
With the system seemingly full-proof, what role does an air traffic controller play?
The role is critical.
For instance, last year’s incident involving Vistara and Air India flights shows the importance of a composed and alert controller. And the danger, when the controller isn’t on top of his game.
Investigations after the incident revealed that even as the two aircraft — the Vistara plane was Pune-bound from Delhi while the Air India flight was flying to Bhopal — were on collision course, the ATC got into an argument with the Vistara pilots on instructions to be followed. Fortunately, the Air India pilot followed standard operating procedure and a tragedy was averted. There were 261 passengers on board the two flights.
While AAI de-rostered the radar controller at the ATC centre, the two Vistara pilots were grounded.
Better technology, but…
Technology has improved by leaps and bounds since a horrific mid-air collision in 2002 between Russia’s Bashkirian Airlines and a DHL cargo jet over Germany, killing all 71 passengers involved, including many schoolchildren. The cargo jet was incorrectly asked to change its course by an ATC, leading to the collision.
Though work on TCAS had been on since the 1950s, incidents such as the Bashkirian disaster prompted faster improvements.
Technology saved the lives of those in the Vistara and Air India flights. But the element of human involvement still plays a critical role.
“Accidents due to technology glitches have reduced. But accidents due to human error have increased,” says S Mangala, DGM (Aviation Safety, WR), AAI.
A whistleblower, Mangala has taken AAI to court, alleging that her employer has been lax about safety norms.
The IndiGo Airlines incident
The air miss or air proximity involving the two IndiGo airlines could have taken place because of one of three reasons:
“The ATC may have given wrong instructions to the pilots; the ATC may have given the right instructions, but the pilots may have heard it wrong, or followed them incorrectly; or, ATC may have given the instruction to one pilot, but another pilot – given the aircraft congestion in the air – may have thought that the directive was for him or her,” explains Mangala.
IndiGo didn’t respond to questions from Moneycontrol.
Whenever an ATC gives an instruction to a pilot, the pilot is supposed to read back the instruction to the controller to ensure the message is correct.
“Sometimes, a pilot will hear what he or she wants to hear. Because at a particular height, he may be getting a better tailwind (which would help complete the flight faster and burn less fuel), or maybe at that height he can escape clouds, like in the monsoon season,” says the AAI officer.
But this miscommunication can have fatal consequences. The pilot, for instance, may have got the instructions wrong because of fatigue.
Earlier this year, Delhi High Court pulled up DGCA for granting airlines exemption and deviation from maximum limit of flying timing for pilots. The court said fatigued pilots and crew were a risk to passenger safety.
Shenoy, whose plea led to the High Court order, said DGCA was violating the rule that limits a pilot’s flying to 125 hours over 30 days.
“According to rules, pilots can’t fly for more than eight hours. But in India, some of them do duty for up to 12 hours,” he told Moneycontrol. “Just imagine sitting in that small cockpit, which has a compressed atmosphere and where oxygen levels are not normal for more than three hours at a time,” he added.
Safety experts have also highlighted the way Flight and Duty Time Limitation, or FDTL, is computed by Indian airlines. “Indian airlines don’t take into account transportation time,” says Ranganathan. “For instance, if the pilot is traveling from Noida to the Delhi airport, he has already spent two hours on the road. This adds to the stress,” adds the former pilot.
Mangala points out at similar fatigue issues among ATC officers. “Overall, the ATCs are well-staffed. But some centres are overstaffed. The use of human resource is not scientific,” she says.
Despite the High Court order, alleges Shenoy, the DGCA sent out a circular in June that again let airlines ask for exemptions and deviations when it comes to Flight and Duty Time Limitation.
DGCA and AAI didn’t respond to mails from Moneycontrol.
There is also suppression of information, adds Mangala. “After 2014, AAI is deliberately not putting the number of air miss incidents in its safety audit reports. Why the suppression of safety information by AAI and DGCA? Why don’t AAI and DGCA put on their websites all the information about the air misses and reports of the AIT ( Air traffic Investigation Team)?” she asks.
Mangala has alleged in her petition in Bombay High Court, that she was asked by her employer to sign on fake investigation reports, and she refused to do so.
Is there pressure on AAI to show the situation is in control?
Every year, the Airports Authority signs a memorandum of understanding with the Ministry of Civil Aviation. In the memorandum, AAI specifies its safety targets, including limiting the number of air misses to a particular number. This is the reason, says Mangala, that AAI has stopped publishing the numbers.
“It is a collective failure,” reiterates Shenoy. “We are surviving by God’s grace,” he says.