Boeing crash probe protocol seen hampered by Iran-US tensions
There are clear international rules governing investigations into air crashes, but in the case of Wednesday's Ukrainian passenger jet disaster in Iran they are likely to fall victim to heightened tensions between Tehran and Washington.
The Ukraine International Airlines Boeing 737-800 crashed less than three minutes after taking off from Tehran's airport, killing 176, mostly Iranians and Canadians.
Tehran has already indicated it would not hand over to Americans the recovered flight recorders, the so-called black boxes, for investigation.
The rules on probes into air crashes are set down in the 1944 Chicago Convention on International Civil Aviation, and the responsibility for the investigations is assigned to the countries where they occur.
This puts Iran in charge of the investigation, but the country that manufactured the aircraft and the country of the airline that operated the plane are also to have representatives involved in the probe.
In theory this means that the US National Transportation Safety Board, which is the body charged with investigating air accidents, would be involved as Boeing is based in the United States, and would likely rely on experts from the manufacturer.
"That could be a little complicated," said Jean-Paul Troadec, former head of France's BEA airline safety agency.
The crash came on the same day that US-Iranian tensions rose to new heights as Iran fired a volley of missiles at Iraqi bases housing US and other foreign troops, the Islamic republic's first act in its promised revenge for the US killing of a top Iranian general.
Boeing said it was in contact with Ukraine International Airlines and that it was "ready to assist in any way needed".
However, the head of Iran Civil Aviation Organisation head, Ali Abedzadeh, said while the Ukrainians were free to participate in the probe into the crash, "we will not give the black boxes to the manufacturer (Boeing) and the Americans," according to the Mehr news agency.
Reading information from the cockpit voice recorder and flight data recorder is not in itself difficult, according to Troadec.
"The difficulty is if the recorders are in very poor condition, then you need labs which have the experience and equipment" in recovering data, he said.
Besides the NTSB, Troadec said the BAE and its counterparts in Britain and Germany have the know-how to handle data recovery in such situations, and possibly the Russians.
The BEA said it has yet to receive any request for assistance from the Ukrainian authorities.
The Chicago Convention also allows a country to let another country take charge of a probe.
Dutch authorities carried out the investigations into the 2014 crash of a Malaysia Airlines that crashed in Ukraine as it returned home from Amsterdam, killing 298 people including 193 Dutch nationals