Etihad Airways has signed a code-share agreement with Turkish Airlines, under which the Abu Dhabi-based airline will place its two-letter 'EY' code on Turkish Airlines' flights from Istanbul to the UAE's capital city and the Turkish airline will place its two-letter 'TK' code on Etihad Airways' flights from Abu Dhabi to Istanbul. The agreement comes on the heels of the launch of Etihad's four flights a week service to the Turkey's commercial capital, Istanbul, which began on June 1, 2009.