This blogpost provide some insight on the way Dutch Safety Board determined the location of the explosion of the BUK missile. Based on the location of the explosion, the location of where the missile was launched from can be calculated.
Around July 2016 the JIT will announce the exactly launch location. This location could be determined by satellite photos, SBIR data and calculations.
To be able to verify the JIT conclusion on where the missile was launched from, we need to understand how JIT likely did the calculation.
The main issue in calculating the location of both explosion and launch is that some parameters are not exactly known. So this is why DSB calculated an area of 320 square km as possilble launch location, while Kiev Research Institute for Forensic Expertise calculated a very small area.
Assessment of damage pattern
DSB performed an assessment of the damage of the aircraft other skin. They looked at which part of the fuselage was hit by fragments and which part not. The border between area’s hit and area’s not hit is important.
NLR calls this “the search for a ribbon of perforations over the aircraft contour”.
To establish the border provides information on the location of the missile when it exploded.
Another part of the assessment is trying to find out if certain area’s had specific shapes of holes. Each warhead has a kind of fingerprint. DSB stated that a ribbon on the righthand side of the cockpit was hit by a relative large number of bow-tie shaped fragments.
Also DSB looked at the pitch. The pitch is distance between holes made by fragments. The idea is that because of a warhead with preformed fragments a certain pattern can be observed. The trajectory of the preformed fragments can be calculated. Based on the pitch distance between warhead and aircraft can be calculated.
DSB also studied the damage of the blast caused by the explosion on the aircraft fuselage.
DSB found a couple of bow-tie shaped fragments. DSB concluded based on the bow-tie that the only weapon which could be used was a 9N314M warhead.
Probably DSB then reversed enginered the location of the explosion based on the found bow-ties.
The 9N314M warhead has a couple of characteristics which determine the damage pattern on the warhead.
- the shape of the warhead. The warhead is barrelshaped. This leads to a certain minimum ejection angle and maximum ejection angle.
- the location of the detonator. This determines the ejection angle. If the detonator is located in the front of the warhead, fragments will be pushed out more backwards then when using a detonator located in the back or middle
- preformed fragments. The 9N413M warhead has preformed fragments. This means each fragment has a distinct shape and is put loose into the warhead in a pattern. The alternative is pre-ready fragments. In this situation the fragments are not loose but are fixed to eachother. The force of the explosion creates random shaped fragments.
- weight of the fragments. Heavy fragments have higher speed of the explosion due to the kinetic energy. Higher speed of the fragment combined with the speed of the missile mean a different distribution of fragments compared to light fragments.
- number of light and heavy fragments
Other parameters which are important in locating the location of the missile when it exploded are :
- speed of the missile
- speed of the aircraft
- the logic of the proximity fuse. A BUK warhead has a proximity fuse. It detects that it is near the target and will then detonate the explosives. The conditions for detonation tell more about when and at what location the BUK missile explodes.
- direction the aircraft flew in relative to the ground (not the magnetic course but the true track)
- direction of the missile relative to the ground
- type of explosive used in missile
- density of the air. This has a result on the drag of the fragments and this speed. However the effect is quite low
- pitting. The damage caused by hot parts of the explosives
- soot. The black residue of the explosion
The speed and altitude of the aircraft has an additional effect. After the explosion the pressured cabine will put force from the inside to the outside. Additionally the forces of the aircraft caused by the speed and the wind will have an impact on damage patterns.
How to calculate the velocity of the fragments
The speed of the fragments after the explosion can be calculated using the Gurney equations.
(Enter: cyclotol, 33, 37, cylindrical. AFAIK Buk warhead uses a TNT/RDX mix)
Based on all these parameters the location relative to the nose of the aircraft can be determined. Characteristics of the location of the missile are:
- x= location relative on the horizontal axis of the aircraft (in front or behind the nose)
- y= location on the horizontal axis (left or right of the nose)
- z= location on the vertical axis of the nose (up or below the nose)
Then the elevation and azimuth of the missle are determined by DSB.
The elevation is the angle of the missile when it exploded relative to the horizon.
The azimuth is the angle of the missile relative to the course of the aircraft.
2 D Simulator of fragment distribution
To get a basic understanding of the effect on fragment distribution this is a nice 2D simuation. Mike West made this simulation. It can be used to see the effect of missile spead, aircraft speed, spread on distribution of fragments.
TNO used commercial closed source software named Split-X to calculate the distribution of fragments on a 3D model of a Boeing 777. TNO used three different models of a warhead. Each model had different characteristics like ejection angle and number of light and heavy fragments.
How to determine launch location
A user called Eugene made a nice animated GIF about the process of determination of the launch location. By publishing I don’t necessarily agree with the finding.
Eugene used a track course of 123 while in fact the aircraft course on a flat map was 119 degrees.
Open source calculation of launch spot
Someone with nickname Unit0 wrote a VisualBasic code to determine the launch area. He used several parameters. In a future post I will try to explain all the parameters. The result of this calculation differers from the results of the Eugene method.
For now I show the thread at Metabunk which shows the calculation.
Unit0 made a new calculation in April 2016. The result is shown in the image below. The black area is the most lilely launch location.
The center of the area is south of Red October/ Chervonyi Zhovten