The Emergency Interseat Sequencing System (EISS) was designed an qualified for the F-15K Fighter and has since been installed in the F-15SG and F-15SA configurations of the F-15. The system consists of Thermal Batteries with Initiators, a Digital Interseat Sequencer, Mode Selector, and customer provided cabling Electro-Explosive Devices (EEDs). The system is operated from either thermal battery and aircraft 28Vdc for redundancy. A separate field Test Set (EESSTS) performs both complete system continuity tests and an operational test of the total system installed in the aircraft. The sequencer is programmable and could be used in any escape system.
Based on the initiation point, Forward or Aft Seat Handle, Internal or External Canopy Jettison Handles, and the Mode Selector setting, the Sequencer provides firing pulses to the EEDs to support canopy removal, ejection seat inertial reel activation(s) and ejection seat catapult firing(s). Sensing capabilities are provided to determine system state, canopy gone, seat gone, so as to provide the optimum escape timing.