Turkey ordered an Armenian aircraft bound for Syria to land on Thursday.
Authorities were searching the plane's cargo in the second such move by Ankara in a month.
Searches like this are designed to prevent the use of its airspace to provide supplies to the Syrian military.
According to a Turkish broadcaster the plane was carrying humanitarian aid.
In mid-October another Armenian plane was also stopped and searched, before continuing on its way.
Turkey has become increasingly assertive in challenging Syrian President Bashar al-Assad.
Last month, Ankara banned Syrian aircraft from Turkish airspace after finding Russian munitions onboard a plane bound for Syria.
