The primary cause of the setback was the closure of wide parts of European airspace over six days in reaction to the elevated ash concentration in the atmosphere due to the eruption of the Eyjafjallajökull volcano in Iceland.

At points, over 300 European airports were closed, affecting nearly 10 million passengers worldwide. On a year-on-year basis Europe lost 14% of passenger traffic in April, while North America dropped 1%, with the New York area airports losing traffic disproportionately; North America is the largest market for flights in or out of Europe.

"April results put a sobering brake on the growth trajectory to which the industry had returned. Europe had already been struggling with a slower recovery compared to other regions, but April results were even worse than during the height of the financial crisis, "said Andreas Schimm, Director of Economics for ACI World.

Airports in the UK and Ireland, and Scandinavian countries were among the most affected registering losses up to over 30% while airports in Turkey and Russia continued to experience double-digit growth.
 
Other regions, less dependent on European traffic had appreciable volume despite repercussions from the European airspace closures; specifically Asia Pacific (+10%), Middle East (+10%), Latin America-Caribbean (+7%), and Africa (+3%). The Africa result does show a more negative impact of the closures, whereas more than half of the airports in the ACI sample grew by double digits.

"The growth scenario continues to be intact and we expect this anomaly to be a unique case as the volcano seems to have gone dormant, and operating procedures for similar situations in the future have been improved allowing for more flexible operations. It is important however, that current international standards continue to be revised together with much improved collection of actual data on ash concentration which should avoid similar measures by national authorities in the future," comments Schimm.

The impact of the ash crisis on freight in April is not pronounced, but it has caused the international growth trend to dip particularly in Europe. Despite these effects, international freight still expanded by 27% versus 10% growth in domestic freight. Domestic freight is dominated by North America where it expanded by 11% while less voluminous international freight impressed with +32%, only topped by Asia Pacific where international freight was boosted 37%. Major freight airports that registered high growth in April were Hong Kong (+38%), Shanghai Pudong (+46%), Miami (+30%), Incheon (+27%), Taipei (+54%) and Los Angeles (+28%).

"International freight is still in catch-up mode continuing to provide hope for a sustained and broad economic recovery.

As the inventory cycle is coming to and end, and government stimulus gradually phases out year-on-year, air freight growth is likely to moderate in the months to come." says Schimm.