BBC News
19 July 2014

The investigation into the MH17 air disaster is fraught with difficulties.

The crash site is in territory controlled by pro-Russian separatists. Jurisdiction and control over what emerges as the full account of what happened will be contested fiercely. Even beyond the human tragedy, the stakes could scarcely be higher, with the future direction of the Ukraine crisis seemingly in the balance.

As global anger and shock mounts over the apparent shooting down of the passenger aircraft, here are some of the key issues surrounding what could be a highly contentious air crash investigation.

Who has jurisdiction?

“Responsibility for an investigation belongs to the state in which the accident or incident occurred,” according to the International Civil Aviation Organization (ICAO), a UN body.

However, almost any major air crash inquiry will be an international affair that draws in other nations due to their technical expertise, resources or – as in this case – the political ramifications of the disaster.

When Malaysia Airlines flight MH370 went missing in March, Malaysia headed the inquiry but invited numerous other countries to participate. In the latest disaster, nations with passengers aboard the doomed jet will likely want to play a role, or launch their own inquiries.

A number of Western nations have already called for a full, independent, international investigation into what happened.

Meanwhile, the Russia-led Interstate Aviation Committee (IAC) – the official aviation authority in Russia which counts former Soviet states, including Ukraine, as signatories to its treaty – says any inquiry should be set up under the auspices of the ICAO.

How do you investigate in a conflict zone?

The safety of anyone involved in the investigation will be paramount, as will unfettered access to the site, the security of the debris field – including the flight recorders, and access to anyone who might have seen the crash or be able to shed light on what happened.

Pro-Russian rebels say they will allow international investigators to access the crash site via some kind of humanitarian corridor, but there are international calls for a complete cessation of hostilities to allow a rapid independent investigation.

The first observers from the OSCE team on the spot were restricted in their movements by rebel commanders.

There are also already concerns over the whereabouts of the flight’s “black box” recorders. Reports say rebels already have at least some of the aircraft’s data recorders in their possession and that they had promised to give them to the Moscow-based IAC.

However there is confusion about their location. The OSCE team said they found no-one with information about them.

The uncontrolled removal of items from the debris field could have serious implications for the integrity of the air crash investigation, experts say.

Don’t we already know what happened?

The US intelligence authorities say their monitoring systems suggest a surface-to-air missile brought down the plane, but it was not yet clear who fired it. The two sides in Ukraine’s civil conflict have accused each other of shooting down the jet.

On recordings said to be of intercepted phone calls between a separatist fighter and a Russian military intelligence officer – sourced to the Ukraine’s main security agency, the SBU – the two men apparently discuss the shooting down of a civilian plane in the minutes after MH17 crashed.

But the calls are unverified. And rebels insist their equipment is not capable of bringing down an aircraft at more than 30,000 feet – and that Ukrainian troops must be responsible.

Intelligence agencies will be “crawling all over” the calls and other information from the crash site, Michael Clarke of the Royal United Services Institute told the BBC.

“With what is known in the West together with these things they will probably get to the bottom of it very quickly” but there will likely always be room for doubts, the expert said.

What will investigators focus on?

Former US National Transportation Safety Board (NTSB) Chairman Deborah Hersman said the “road map” for investigators in the first day or two would be finding all “four corners of the aircraft” – the nose, the tail and the two wing tips – as well as the flight data recorder and the cockpit voice recorder.

Investigators would be looking to “sequence” the break up of the plane – find out where it started and how it spread, Ms Hersman told US network NBC.

The flight data recorder will reveal the exact time of the incident and the altitude and exact position of the aircraft, while the cockpit voice recorder will reveal what the crew knew was happening before disaster struck.

Russian experts quoted by the Kommersant newspaper (in Russian), have been detailing what the wreckage of an plane hit by different missiles should look like.

“If this was a Buk, we should expect to see holes in the fuselage, wings etc. But if it was an air-to-air missile, then we should expect elongated ‘cuts’ along the body of the plane, as opposed to ‘holes’.”

Why are the stakes so high?

Correspondents say that if it does turn out that the Boeing 777 was shot down by the separatists – with weaponry supplied by Moscow – then it could significantly alter the terms of the whole debate surrounding the Ukraine crisis.

The disaster comes at a time of already soaring tensions.

This week the Ukrainian authorities accused Russia of downing a Ukrainian military plane on a mission over the east of the country on Wednesday, killing two of the eight crew members on board.

Russia called the accusation – the first direct claim of a Russian attack on Ukrainian forces – “absurd”.

Meanwhile there has been serious fallout from fresh US and EU sanctions against Russia. Moscow has condemned them as “blackmail” and warned of retaliatory action against Washington.