On 23 March 2009 between 6:00 and 6:40 UT, three THEMIS probes (P3, P4, and P5) were at about −11.5 Earth radii (RE) and two (P1 and P2) were at −14 RE downtail. The inner probes (P3-P5) started to observe oscillatory flow braking with plasma sheet dipolarization due to flux pileup at about 6:04 UT. After 6:16 UT the flux pileup region (FPR) expanded tailward as the outer probes (P1 and P2) moved closer to the neutral sheet and began to observe oscillatory braking also. During the FPR tailward expansion, the flow oscillation period increased from about 3.5 minutes at P3-P5 to about 6.2 minutes at P1 and P2. Meanwhile, as observed by the all-sky camera at Rankin Inlet, auroral activity gradually moved northward indicating that the characteristics of oscillatory flows at the tailward retreating FPR may be crucial for understanding the magnetosphere-ionosphere coupling.