China Eastern Airlines and Shanghai Airlines expanded their codeshare arrangement with an eye toward solidifying their presence at their increasingly competitive Shanghai hub.

The new accord, which goes into effect March 1, will see each carrier place its code on the other's flights to Harbin, Tianjin, Chengdu, Chongqing and Shenzhen for a probationary period lasting until March 29. At that point, if the airlines agree, the cooperation will be extended to the end of the summer schedule.

In addition, CEA and SAL plan to codeshare on flights to Hong Kong and Macau this year. Last fall they signed a codeshare deal covering flights to Huhhot, Nanning, Urumqi and Xuzhou that expires on March 29.

SAL Chairman Zhou Chi noted recently that the carrier is looking at expanding its relationship with CEA. Further codesharing, slot coordination and even the delivery of transfer passengers to each other's flights are under discussion. Currently, CEA holds a 36% share of the Shanghai market while SAL has 18%.