ATR72 Bangkok Airways Accident – Technical Analysis I

Let’s start first with some facts to introduce any further technical discussion:

METAR:

VTSM 040700Z 29015KT 9000 FEW020TCU SCT120 BKN300 31/25 Q1007 A2974 TCU-NW

(accident occurred around 07:30Z, 30 minutes later after this METAR was issued. Heavy rain was observed at the time of the accident)

Runway in use: 35

Crosswind Componed based on METAR wind and runway heading: 13 Knots

Koh samui Airport Map

 

The ATR72 was landing on runway 35 and impacted at low-medium speed range (from my first photos analysis at a speed of around 40KT) the control tower at approximately half runway lenght during the landing roll and breaking.

Probably until further info – main and contributing factors which caused the crash are, in a mostly chronological order:

– No instrument approach procedure established for VTSM

– Maybe a non-perfectly stable approach caused by atmosphere instability (FEW020TCU – Towering Cumulus – shows instability at low level)

– Moderate crosswind component which makes the transition phase between flight phase and ground roll critical in case of wet or contaminated runway with low friction coefficient, especially regarding the directional control of the aircraft. Improper or overcorrecting ailerons, rudder and/or nosewheel inputs could result in a loss of directional control of the aircraft.

This first analisys is assuming that no technical problem was encountered by the a/c during that flight.

Marcello S.

3 risposte a “ATR72 Bangkok Airways Accident – Technical Analysis I

  1. Interessante report,
    sebbene un po´ scontato:
    piccolo aeroporto in Thailandia.
    Condizioni meteo difficili come solo li´ sanno esserlo.
    Scarse infrastrutture di supporto a terra (ILS).
    Difficolta´ di controllo in atterraggio su pista bagnata in presenta di forti turbolenze e vento al traverso.
    Insomma…la notizia qui e´ che non ci sia stato un crash totale!

  2. Pingback: Incidente a Koh Samui « FlyerZ Blog

  3. Well, my analysis made on Wednesday is being confirmed every day more by the authorities investigating the accident. In addition, gusty winds due to atmosphere instability were observed as previously mentioned.

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