On Friday August 07 this year, Air India Express Flight IX 1344, a Boeing 737 airliner with 190 persons on board that was on a Vande Bharat Mission sponsored by the government to bring back Indian citizens stranded abroad, took off from Dubai for Calicut International Airport, Kozhikode in Kerala, ended up in a disaster at 1941 hours when trying to land at the destination airport. The airliner overshot the runway and fell into a gorge 35 feet deep on account of which, the fuselage broke into two pieces. The captain of the aircraft Deepak Vasant Sathe, the co-pilot Akhilesh Kumar, four members of the cabin crew and 14 passengers perished in the accident. Apart from these fatalities, over 100 passengers were seriously injured. The fact that the wreckage did not catch fire was indeed fortunate as if it had, possibly none would have survived the accident. This was the worst disaster that Air India Express has suffered since the loss of a Boeing 737 aircraft that overshot the runway while landing on the table top runway at Mangaluru airport and fell into a deep gorge killing all 158 on board. The difference was that the accident in 2010 was in the day time and in good weather whereas in the accident at Calicut, the landing was attempted at night time and in extremely adverse weather conditions.

Calicut International Airport, also known as Karipur Airport, is located in Karipur which is in Malappuram district of Kerala. The airport serves South Malabar region of Kozhikode, Malappuram, Palakkad and Wayanad.

WHAT LED TO THE ACCIDENT?

The Black Box which contains the Digital Flight Data Recorder (DFDR) and the Cockpit Voice Recorder (CVR), has been recovered from the wreckage and only after the data is retrieved and analysed by the Aircraft Accident Investigation Bureau under the Ministry of Civil Aviation, can the precise cause of the accident be established. As this will take time, here is an attempt in the interim to study and analyse the factors available in the public domain that could have led to the disaster.

LANDING IN ADVERSE WEATHER CONDITIONS

First and foremost is the prevailing weather conditions. With an active monsoon this year especially over Kerala, there was heavy rain accompanied by strong and gusty wind conditions in and around Calicut International Airport that has a table top runway 2,860 metres long. There are fairly deep gorges on both ends of the runway as also in some areas along the side of the runway. The orientation of the runway is 280 degrees/100 degrees, nearly East-West. As a landing is normally required to be carried out into wind to achieve a touch down at lower ground speed, given the prevailing wind conditions at that time, the first approach for landing was made by the pilot for runway 28 or the Westerly runway that offered the advantages of strong head wind. However, for some reason which will be ascertained from the CVR, the pilot was unable to execute a landing and carried out a missed approach procedure. Thereafter, the pilot in command decided to make a second attempt at landing, but this time from the opposite direction i.e. Easterly, for runway 10. However, in this attempt, the pilot made an approach for landing with strong tail wind conditions, reported to be around 15 knots, resulting in an overshooting approach and at significantly higher ground speed at the time of touchdown. The second attempt at landing was also abortive. In the third attempt on runway 10, on account of the strong tail wind, the float period got extended and the pilot in command managed to make the aircraft touch down at about 1,000 metres from the beginning of the runway. This left the pilot with just 1,860 metres in which he had to bring the aircraft to a halt.

On account of the heavy rain, the runway was waterlogged. While landing under these conditions, the “Braking Coefficient” is reduced significantly the aircraft is likely to experience “Aquaplaning”, a phenomenon that is also known as “Hydroplaning”. When this happens, the braking system of the aircraft becomes less effective with the Braking Coefficient even reducing to zero. Contact of the wheels with the runway surface reduces drastically resulting in locking of the wheels when the brakes are applied. As a result of this, the aircraft begins to skid with the pilot being unable to control further movement of the aircraft in respect of speed and direction. Under these conditions, brakes become totally ineffective and incapable of reducing the ground speed of the aircraft.

Thus after a touchdown at 1,000 meters from the beginning of the runway 10 and at significantly higher ground speed, the pilot in command was not able to stop the aircraft in the remaining length of the runway and fell into a gorge 35 feet deep after uncontrolled skidding past the end of the runway. It appears that having lost control of the aircraft on the landing run, the pilot foresaw what was coming and possibly shut down both the engines thus obviating the possibility of the wreckage catching fire. The low rate of fatalities in an accident of this kind, can possibly be attributed to this action by the pilot. But what is more intriguing is why the pilot could not manage a successful approach and landing on runway 28 where he would have had head wind conditions. What also needs an answer is as to why the pilot chose to make an approach for landing on runway 10 where he encountered strong tail wind conditions. And more importantly, as per the company policy, the pilot was required to divert to another airport with less severe weather conditions; but he did not choose to do so. There were a number diversionary airfields with less severe weather conditions available for the pilot to choose from such as Kannur, Cochin, Trivandrum, Mangaluru or even Bengaluru. Answers to the question as to why the pilot did not opt to divert will be found in the CVR which will also reveal the communication between the aircraft and the Air Traffic Controller on duty.

TABLE TOP RUNWAY

There are several table top runways across the world including three in India. For operating from table top runways, appropriate training for skill development and formal clearance is required for each runway as these have inherent characteristics and hazards that are not common to all. Operation from table top runways can also be very challenging as these offer very little margin for error. Prior to the crash on August 07, the Calicut airport had recorded four accidents. On August 04, 2017, a SpiceJet flight had skidded on landing and damaged the ILS beacons. The same year on April 25, an Air India flight suffered an engine failure during takeoff leading to a left tyre burst. On July 09, 2012, an Air India Express skidded on landing, again during heavy rain. On November 07, 2008, Air India flight from Jeddah had scraped the runway with its right wingtip while landing.

Following the accident at Mangaluru airport in 2010, a number of improvements were suggested, but these are yet to be implemented

In the case of Calicut airport, the height of the table top runway is only 35 metres. Another limitation of this table top runway is that the Runway End Safety Area (RESA) which caters for overruns, is less than then the prescribed figure, causing a potential safety hazard. There was talk of extending the runway to 3,000 metres and the RESA to the required length, but as the runway is located on top of a hill, it would involve enormous effort and investment to create extra land at that height at both ends of the runway.

The airport at Calicut was upgraded to international status in 2006 and today it is the 11th busiest airport in the country in terms of traffic. Following the accident at Mangaluru airport in 2010, a number of improvements were suggested, but these are yet to be implemented. There is a standard operating procedure (SOP) laid down by the Directorate General of Civil Aviation for removing water from the runway. As to whether or not this SOP was followed at Calicut International Airport in this case, will be known after the investigations are over.

PROFESSIONAL CREDENTIALS OF THE PILOTS IN COMMAND

Captain Deepak Vasant Sathe, the captain of the ill fated Air India Express flight, had joined the National Defence Academy as an Air Force Cadet and was commissioned into the Indian Air Force (IAF) as a fighter pilot in June 1981. He served with No. 17 Golden Arrows Squadron that is now being reequipped with Rafale jets. Deepak Sathe was also trained as a Test Pilot in the IAF. While serving as a fighter pilot, he was involved in flying accident in the early 1990s in which he suffered serious head injury. However, due to his strong will power and passion for flying, he successfully returned to military flying. He took premature retirement in the rank of Wing Commander after 21 years of service and migrated to civil aviation. He joined Air India in 2013. Captain Sathe was undoubtedly endowed with outstanding professional credentials.

Akhilesh Kumar, the co-pilot of the ill fated Air India Express flight, began flying with Air India in 2017 and was the first officer of the Air India Express flight in May, which was the first repatriation flight under the Vande Bharat Mission to land in Kozhikode, bringing back stranded Indians in Dubai. He had a total flying experience of 1,723 hours.