NTSC blames slick runway, pilot miscalculations for Pekanbaru runway excursions

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Indonesia's National Transportation Safety Committee (NTSC) has attributed two Lion Air runway excursions in 2011 to a combination of bad runway conditions and the flightcrew's over reliance on weather information provided by air traffic control (ATC).

The excursions occurred one day apart on 14 February 2011 and 15 February 2011 at Pekanbaru's Sultan Kasim Syarif II airport on the island of Sumatra. Both incidents involved Boeing 737-900ER aircraft.

The 14 February excursion caused slight damage to the aircraft registered PK-LFI, while the 15 February excursion caused no damage to aircraft PK-LHH. Both incidents happened in the afternoon amid cloudy and rainy conditions.

Neither incident resulted in injuries or fatalities and all occupants were able to de-plane via stairs.

During both landings, the flightcrew relied on ATC weather information which specified that winds in the area were calm. The pilots made their landing calculations accordingly, apparently without reference to onboard systems. Analysis of the flight-data recorders on both aircraft, however, shows that both 737s had 8-10kt (14.8-18.5km/h) tail winds, resulting in approach speeds 17kt above target for both.

In addition, conditions on runway 36 were found to be slippery, with pooled water up to 3cm deep in places coupled with deposits of rubber from previous landings. This is despite the runway having undergone routine scraping to clear rubber deposits two months earlier in December 2010.

"On [14 February 2011] rubber deposits were found on the runway especially between the thresholds up to the touch down zone," according to the NTSC report involving aircraft PK-LFI.

In both incidents, the NTSC adds, the aircraft performed as expected.

As a result of the excursions, the NTSC had recommendations for the directorate general of civil aviation, airport operator Angkasa Pura II and Lion.

Its recommendations dictate that airport operators work harder to ensure appropriate friction on runways. It also recommends the DGCA ensure that flightcrew have proper simulator training that includes "the criteria of stabilised approach to be included in the simulator training".

The NTSC also recommends that Lion's training curriculum place greater emphasis on stabilised approaches during simulator training, and that pilots should take into account wet runway conditions before landing.

It also specified that Lion needs "to provide a comprehensive system to ensure the electrical power to the [cockpit voice recorder] disconnect immediate after the serious incident to prevent automatic overwriting of the information".

After the PK-LFI incident, the CVR continued to receive electricity for 30min while the crew waited for the arrival of airport personnel. This caused the entire recording of flightcrew conversations during the approach, landing and subsequent excursion to be overwritten.

When the 14 February 2011 incident occurred, PK-LFI was serving the Jakarta-Pekanbaru route with seven flightcrew and 212 passengers. The NTSC indicates that Lion did not provide total hours or total hours on the type for either pilot.

When the 15 February 2011 incident occurred, PK-LHH was serving the Medan-Pekanbaru route with eight crew and 218 passengers. The pilot had 11,000 flying hours with 1,709h on type. Lion did not provide total hours or total hours on the type for the co-pilot.