Why are passenger planes flying over war zones?

More than 300 people are believed to have died after the MH17 flight crashed near the Russian border of eastern Ukraine. Details are still unclear but it appears that the plane may have been shot down with a surface-to-air missile.

In response to the accident, flights have been re-routed and airlines across the world are warning pilots to avoid the area.

A Department for Transport spokesman said: “Flights already airborne are being routed around the area by air traffic control in the region. Pilots around the world have been advised to plan routes that avoid the area by Eurocontrol, the European organisation for the safety of air navigation.”

Immediately after the crash, four more planes followed the same path and did not re-route: Singapore Airlines, Emirates, Kazakhstan Airlines and Etihad. Since then, all planes are being advised to seek alternative routes – which can be seen in live maps of international airspace.

However, why were planes full of innocent travellers flying over war zones in the first place?

‘Possible existence of serious risks’

In April and again in updated guidance in June, both the American authorities and the European air authorities, Eurocontrol, advised against flying over the area mainly because it was unclear who was controlling the airspace – Ukraine or Russia – which could lead to misidentification and confusion over civilian flights. On the ground, the area is in the hands of separatists.

“The agency draws the aviation communities’ attention to the possible existence of serious risks to the safety of international civil flights… consideration should be given to avoid the airspace and circumnavigate [the area],” the warning said.

However, the guidance is not mandatory – although it would be rare for airlines to disregard it without good cause. It is unclear exactly where the plane was when it was shot down and as such whether the warnings applied. The warnings apply to altitude as well as geographical location – and it appears the plane was just higher than restricted airspace.

The plane is believed to have been flying at 33,000 feet – a height which missiles could theoretically reach, but which is just above the limit of 32,000 feet set by the air authorities for planes in that airspace.

The Civil Aviation Authority pointed out that closing airspace completely was the responsibility of the country: “The Ukrainian authorities are responsible for managing their airspace and the UK or other countries cannot enforce airspace restrictions in the area.

“However, the CAA has previously issued advice to UK airlines on operating in this area and following this incident, Eurocontrol has issued advice to airlines to plan routes that avoid the area.”

Late on Thursday Eurocontrol announced that the airspace over eastern Ukraine was closed.

The detail remains unclear: but what is clear is that the plane was flying at least very near to airspace with strong warnings over it, and in an area where pro-Russian separatists recently shot down another plane.