June 2009 looks set to be the most expensive month in the aviation insurance market since September 2001, a report by Aon has revealed.

Last month saw two large losses, the most recent being the crash of an Airbus A310-300 operated by Yemenia, which was lost near the Comoros Islands in the Indian Ocean on June 30. The loss happened while the aircraft was on a flight from Yemen's capital Sanaa to Moroni, the capital of the Comoros Islands. The aircraft was valued at around $34m. Ace was the lead insurer on the aircraft's hull account.

Earlier that month, an Air France Airbus A330 crashed into the ocean off the coast of Brazil en route to Paris. The insured value of the hull is estimated to be around $99m, and Axa was the lead underwriter.

According to Aon's report Airline Insurance Market News - July 2009, these two losses are likely to turn June into the most expensive month for claims under standard hull and liability policies ever, excluding September 2001 when the World Trade Center attacks took place.

The report added that aviation claims so far this year - including an estimate for minor losses - are already around 11% higher than the average for a full year.

The loss figure excluding minor losses is $1.3bn so far in 2009, compared to $457m recorded at the same point last year. Taking an annual pro-rata estimate for minor losses into account, the overall loss total for the year to date is $1.6bn, compared to $715m in 2008.