High Altitude Long Endurance (HALE)

High Altitude Long Endurance (HALE)

Long mission duration for the ultimate persistent surveillance.


Boeing designed and tested Phantom Eye, a high altitude, long endurance (HALE), unmanned aerial system (UAS) demonstrator to provide affordable, ultra-persistent intelligence, surveillance and reconnaissance, missile defense or other missions.

The Phantom Eye demonstrator, completed its maiden flight on June 1, 2012 and performed a total of nine flights at altitudes up to 53,000 feet, successfully demonstrating a hydrogen propulsion system.

The Phantom Eye demonstrator paved the way for an operational HALE UAS to fly at 65,000 feet for up to 10 days without refueling and with 270 nm sensing line-of-sight. It could carry a variety of payloads, including communications and multiple sensor packages for monitoring and tracking.


The HALE UAS makes the stratosphere accessible and affordable:

  • Transformational range enables theater monitoring from afar
  • Twin engines, independent fuel supplies and redundant vehicle management systems
  • Up to 10 days endurance at 65,000 ft - 20 days endurance at 20,000-25,000 ft
  • Long mission duration, high system reliability, autonomy and fuel efficiency
  • Sensing line of sight (LOS) Horizon > 270 nm
  • Redundant systems for reliability
  • Low operating costs per hour
  • Able to complete the mission with one engine inoperable