AIRASIA INDONESIA QZ8501
1. Indonesia AirAsia QZ8501/AWQ8501 scheduled to arrived at Changi Airport singapore from Juanda International Airport surabaya, Indonesia at 8:30 a.m on 28th December 2014.
2. Manufactured by Airbus,A320-216, with registration number PK-AXC person on board (p.o.b) 155 passengers and seven crews on board.
3. Bad weather become the prime suspect for bring down airasia QZ8501.
4. The pilots requested to divert the plane from originated flight plan to avoid clouds (cumulonimbus cloud).
CUMULONIMBUS CLOUD (CB)
5. The cumulonimbus cloud is the worst enemy for the pilots to deal with. The pilots taught to avoid this kind of cloud in any circumstances.
6. The cumulonimbus cloud not only brings heavy precipitation but there are another harmful causes that can bring the QZ8501 down such as lightning, icing condition, turbulence and unstable upward and downward air flow. These combination is the best recipe to bring QZ8501 down.
7. The pilots requested to divert to the left and climb from FL320 (32000 ft) to FL380 (38000 ft). The official report from indonesia meteorological agency told that some of the cumulonimbus clouds on that day rising to a height of nearly 45000 ft had been observed in the plane's route. There is the chance for the QZ8501 to meet by the clouds.
8. Heavy precipitation does not give the main cause to bring down the plane, the visibility for the pilots just decrease.In the modern world of aircraft, that is not the big problem, big commercial aircraft such as Airbus A320-216 with sophisticated instrument the pilots not only depend on Visual Flying Rules (VFR) only and can rely on the instruments to aviate and navigate the plane (IFR).
9. Lightning from the cumulonimbus may be have a responsibility to bring down QZ8501, the current from lightning can interupt instruments attch in the cockpit or not. But the pilots can still cope with this situation because not all instruments are from electrical based there are also gyroscopic based instruments.In nowadays designation of modern aircraft, the body of the aircraft can resist when the lightning struck and earthing the current harmlessly.
10.The major threat for cruising/flying in the cumulonimbus cloud is icing, icing condition.
11.Icing condition can occur in two type of ice formation. In the solid state, hails appear, and in the liquid state,supercooled water droplet appear.
12.Hails can cause the plane down, hail can be 'trash' in the air.It can let the engine to flame out.
13.Jet engine consist with several segments such as compressor, turbine and combustion chamber. These parts have their own stress/strain/fatigue limitations. If hit by something that has more force from its limitation it can dent or in the worst case break apart.
14.Hit by the continuously hails can jammed the engine itself, in engineering word, 'surge'. Surge occurs in engine will destroy the usual air flow in the engine and the force from this 'turbulence' in the engine will tear apart every component that built in the engine. Engine flame out will take part.No thrust to the plane.Checklist manual for engine flame out is unusable when the engine physically tear apart.
ENGINE FLAME OUT
15.In the event of engine flame out, no thrust detected, so the plane now not more than a glider.A perfect glider is not suitable in the cumulonimbus cloud when the turbulence created by the cloud itself from the updraft and downdraft gusting from the cloud. Like a piece of paper in the middle of tornado wind.
16.In sophisticated airplane like A320-216, all the electrical source are from the engine, now the both engine are flame outs, hydraulic system will be dead too.Now how the pilots can steer the plane with the cripple plane.(Hydraulic not working;aileron,stabilizer and rudder are dead.
17.Yes, the pilots can deploy the small turbine fan to generate the electricity but in the chaos updraft and downdraft situation,the possibility to cope in this situation is small.
SUPERCOOLED WATER DROPLET
18.Supercooled water droplet (swd), the other suspect that can lead QZ8501 accident happens.
19.In "cold" clouds, where the temperature is below 0°C, ice crystals and supercooled droplets co-exist.
20.In these 'mixed' clouds, the air is close to being saturated with respect to liquid water, but is super-saturated (an unstable phase) with respect to ice.
21.Supercooled droplets are in an unstable state and usually start to freeze when brought into contact with ice crystals and particles with a similar structure to an ice particle (freezing nucleus).
22.Let's talk with our prime suspect for bring down QZ8501 in details :
23.Adverse Aerodynamic Effects: Ice accretion on critical parts of an airframe unprotected by a normally functioning anti-icing or de-icing system can modify the airflow pattern around airfoil surfaces such as wings and propeller blades leading to loss of lift, increased drag and a shift in the airfoil centre of pressure. The latter effect may alter longitudinal stability and pitch trim requirements. Longitudinal stability may also be affected by a degradation of lift generated by the horizontal stabiliser. The modified airflow pattern may significantly alter the pressure distribution around flight control surfaces such as ailerons and elevators. If the control surface is unpowered, such changes in pressure distribution can eventually lead to uncommanded control deflections which the pilot may not be able to be overpower.
24.Blockage of pitot tubes and static vents: Partial or complete blockage of the air inlet to any part of a pitot static system can produce errors in the readings of pressure instruments such as Altimeters, Airspeed indicators, and Vertical Speed Indicators. The most likely origin of such occurrences to otherwise serviceable systems has been the non-activation of the built-in electrical heating which these tubes and plates are provided with, although in some cases, the detail design of pitot heads has made them relatively more vulnerable to ice accretion even when functioning as certificated. It is now also recognised that the effects of high level ice crystal icing can have what are usually transient effects on the effectiveness of normally functioning pitot probe heating.
25.Radio communication problems: Historically, ice forming on some types of unheated aerials has been the cause of degraded performance of radios but this has not been encountered in the case of modern radio equipment and aerials.
26.Surface Hazard from Ice Shedding: Ice shed during in-flight de icing is not of a size which could create a hazard should it survive in frozen form until reaching the ground below. However, there has been a long history of ice falls from aircraft waste drain masts, a few of which have caused minor property damage and occasionally come close to hitting and injuring people. The drain masts involved are those from aircraft galleys or toilet compartments which are normally heated to prevent ice formation for some reason have not been operating as intended. Ice from toilet waste masts is often referred to as "blue ice". Most of these events have been recorded where there is a high density of long haul commercial air traffic inbound to a large airport which routinely overflies a densely populated residential area as it descends below the freezing level in the vicinity of the airport.
27.These behaviours can lead to AERODYNAMIC STALL.
28.Aerodynamic stall for an aviation happens where there is no enough air mass flowing over the wing of the aircraft.Thus,no lift created and the plane has the tendency to plunge from the sky.
29.Supercooled water droplet (the unstable water droplet) in crystal state will change to solid form if touched with steel/metal (wing).In that case, solid particle of ice will formed and interrupted the air flow around the wing area.
30.Flight Data Recorder (FDR) has told that there is 'screaming' from the warning alarm, suggesting aerodynamic stall has happened in QZ8501. The investigators also found that
31.The preliminary report also suggest that QZ8501 ascended suddenly with abnormal rate speed of climb (R.O.C) 6000ft/min.That suggest no more lift generate by stall and with uncontrollable by the pilots the gusting (effect from cumulonimbus cloud) has pushed the wing just like palying the kite at the beach with the headwind (without bernouili's theorem applied).
32.From the previous air crash accident, one reason is not the only cause to plunge a plane.
33.In case of icing situation, just like on the wing of the plane,pitot tube or static tube maybe blocked by the ice formed from supercooled water droplet.
PITOT-STATIC TUBE SYSTEM MALFUNCTION
34.A pitot-static system generally consists of a pitot tube, a static port, and the pitot-static instruments, the system that responsibility to determine an aircraft's airspeed, Mach number, altitude, and altitude trend.
35.Even QZ8501 has passed the cumulonimbus cloud (after going through) the blocked pitot-static system has tell the cockpit the wrong reading of airspeed and their altitude, even the stall speed occur the pilots do not have a window of time to apply stall recovery checklist. Normally occurs when after the plane climb and maintain the plane straight and level for cruising, but the auto-pilot (if alive) will wrongly reading the real airspeed and altitude and trying to correct the wrong reading.
36.After unrecover stall (secondary stall) QZ8501 experienced uncontrollable rolling and spinning before diving and plunging to the sea. The investigators say that the plane took three minutes before plunges into sea.
37.The plane now has a tendency to rolling before entering the spinning stage. At a point,limitation for fuselage design will exceed and the plane will scattered to debrise.
38.For QZ8501,the plane has scattered a few feet before that unlucky aircraft contact with the surface of the sea. That suggest why the debrise of the scattered plane in a small area by the rescuers.
39.The tragedy does not come with a reason but with the combination of bad weather, system malfunctioning, pilot troubleshooting and other distractions.
*This Preliminary Report does not represent the air crash investigation of any air crash investigation bureaus (NTSB,ATSB or NTSC..), This amateur report studied and composed by former cadet pilot. All review are from writer's view and some of it will different from the air crash investigation's specialist report