University College London (UCL) in the UK has released a report that shows the aviation industry has to invest in more research before it can establish robust, safe ash limits for aircraft and engines.
The 25-page report was compiled by UCL's Institute for Risk and Disaster Reduction team in the aftermath of the eruption of Iceland's Eyjafjallajokull volcano.
In the report, researchers said the newly defined safety limits for ash are ad-hoc, arbitrary and not scientifically justified, according to businessweek.com.
It recommends carrying out extensive research to establish safe levels of ash for a wide range of situations, aircraft, engine types and pilot responses.
The study said the inflexible nature of existing aviation protocols and the absence of any pre-existing agreement on safe ash levels worsened the affect of last month's ash crisis.
The study also warned that the Katla volcano near Eyjafjallajokull could erupt in coming months, posing a new danger to flight operations.