The Air India Express Boeing 737-800 aircraft which fell into a gorge at Kozhikode airport had landed more than 1 kilometre down the length of the runway in windy and rainy conditions.
Sources within the Directorate General of Civil Aviation (DGCA), the aviation watchdog, which is leading the investigations into the accident, have confirmed that this is a key factor that they are looking into before reaching a conclusion on whether the remaining length of the runway was sufficient for the aircraft to have stopped safely. What is clear is that the runway surface was wet, a factor that would have impacted the braking performance of the aircraft after it touched down.
Unable to decelerate sufficiently, the Boeing 737 went off the end of the edge of the runway, fell 35 feet into a gorge and slammed into the airport's perimeter wall before coming to a full stop. The fuselage of the aircraft broke into two with the maximum number of casualties being reported from the forward end of the aircraft. Both the pilots of the aircraft perished in the accident.
An animated video play out on Flightradar24, a live flight-tracking app, indicates that Air India Express IX-1344 had aborted its first landing attempt and was making its second and final approach to land considerably faster than what many would consider ideal.
''Flightradar 24 shows the aircraft at 176 knots or 325 kmph at an altitude of approximately 450 feet above the surface of the runway,'' said air safety expert Captain Amit Singh. ''This would not be an ideal ground speed when you are on short finals in these conditions,'' in other words, moments from touchdown.
Flightradar24 data also shows a distinct difference in the approach speeds on the first and second attempt to land. ''During their first approach, they were flying at a ground speed of 149 knots (276 kmph) at an altitude of 2500 feet. Compare that with the second approach, where at a similar altitude, they were making an approach with a ground speed of 191 knots (354 kmph).'' The difference in air speed between the first and the second approach ''could be attributed to the presence of a tail-wind,'' said Captain Singh.
At the time of the first approach to land, visibility was 2 kilometres and there was heavy rain. Reports suggest that the pilots asked Air Traffic Control for permission to land from the opposite end of the runway and proceeded to manoeuvre the aircraft to land despite the presence of the strong tail-wind, reported to be approximately 9 knots or more than 16 kilometres per hour. Landing with a tail-wind component in rainy conditions with a wet runway is often challenging. In this case, the tail-wind would have pushed the aircraft in the direction that it was moving, necessitating additional braking action to bring the jet to a safe stop.
''Tail-winds add to your ground-speed once you touch down,'' says a senior pilot who has operated dozens of flights into Kozhikode Airport. ''In conditions like this, you add a safety margin of at least 15 per cent to the given length of the runway if the runway surface is wet.'' Pilots need to assess wind conditions, the runway surface condition, the landing distance required, the all-up weight of the aircraft, the density of the air and the presence of wind-shear or unexpected and difficult to detect wind conditions, potentially at low altitudes.
If IX-1344 floated over the surface of the runway and touched down late, the pilots onboard would have had the option of performing a go-around, where they would bring the aircraft to full power and lift off once again. In this case, the pilots on the aircraft appeared to have committed to stopping the aircraft within the remaining length of the 2.8 km long runway despite touching down 1 km down after its threshold.
The Civil Aviation Minister, Hardeep Puri has also confirmed that there was sufficient fuel onboard the jet for it to fly to an alternate airfield. ''I have asked my colleague, the Chairman and Managing Director of Air India how much fuel did he have. I have an answer,'' said Mr. Puri in a press conference in Kozhikode earlier today. ''There was fuel. Let us wait for the investigations.''
The Flight Data Recorder and the Cockpit Voice Recorder of the Air India Express Boeing 737-800 have been safely retrieved and will be analysed at a laboratory of the DGCA in Delhi.