Todays aircraft, especially fighters, are becoming smaller, faster, and highly sophisticated. This results in a requirement for emergency power at extreme altitudes with little volume available for secondary power. In addition, the fly-by-wire technology requires immediate power with engine flameout at altitude. The traditional auxiliary power unit (APU) does not satisfy this requirement. The APU cannot provide rapid power initiation and does not start well at extreme altitudes. An emergency power unit (EPU) provides rapid power initiation at all altitudes but, requires additional volume and the use of exotic fuels. The optimum power supply can be used on the ground for engine starting and emergency power in the air, even at high altitudes. Combining an APU and an EPU into a single unit will minimize aircraft volume needed for a secondary power system while providing quick reaction to power loss at any altitude. Using conventional jet fuel for the EPU will simplify the operational and maintenance requirements. A device has been developed that combines the APU and EPU into a single unit. This device, called the Multifunction Integrated Power Unit (MIPU) has been successfully demonstrated.