Saudi Arabia’s military blamed a “technical error” for a helicopter crash that killed a pilot during a training mission on Sunday.

The air force machine went down in the Taif area, more than 800 kilometers (500 miles) from the border with Yemen.

A defense ministry statement said the pilot was on a “routine training trip.”

Since March 26, a Saudi-led Arab air coalition has been bombing Iran-backed Houthi militia group in Yemen, while also assisting local anti-rebel forces on the ground.

Coalition helicopters have joined the fight.

In late August, two pilots died when a coalition Apache gunship crashed in Saudi Arabia’s Jazan district along the border.

Houthis said they had shot down an Apache in the same region.

On Sunday, anti-rebel forces in Yemen began a major offensive aimed at pushing the Houthis out of Marib province and eventually moving on the capital Sanaa which the Houthis seized last year.