This paper deals with the design of failure mode power management (PM) of hybrid power systems (HPS) during a shipboard power source failure, which is an important scenario that the all-electric ships (AES) targeting military applications have to deal with. The control objective is to manage the power flow from working power sources and battery to ensure survivability, namely, ensuring system safety and maximizing the load support. The on-demand nature of the problem due to unpredictable failure times makes real-time control a key requirement. The survivability mandates, along with large scale, nonlinear HPS dynamics and long warmup times of the backup power sources, make most of the existing control strategies ineffective to meet the real-time requirements. With the focus on achieving real-time computational efficiency, a novel hierarchical control approach using reference governor is proposed. A top level controller determines a sub-optimal power split between the battery and working source to meet the demand on the HPS and the local controllers govern the power demands for the individual power sources to enforce constraints. A case study of the proposed controller on a scaled HPS test-bed illustrates the real-time computational efficiency and improved HPS survivability.