This research aims to investigate the occurrence of unstable approach from teamwork process via situation awareness, and shared-situation awareness. 9 pilots were recruited for a one-hour interview to identify critical themes. The results depicted that, under congested airspace derived from peak hour and unexpected weather, in order to consume excessive aircraft in the terminal area, ATCOs were prone to issue instructions which sacrificed aircraft's safety margins to squeeze the current air traffic flow. Therefore, aircraft may be too high or too fast during approach. For team process, pilots will actively identify ATCOs intention from TCAS, radio channel, and given instructions. As a result, they will be able to predict the coming steps and make preparation in advance. To conclude, in order to balance the needs of both ATCOs and pilots. ATCOs may have to consider not only separation but the appropriateness of vertical profile. Other than that, during the team process, critical and short information should be provided to make sure both parties comprehend each others intention mutually in seconds.