# L24 Pre-flight **Block 3: IR EW and Signature Management — Lesson 24: IR Countermeasures** *Work this before L24. Pre-flights are never collected — in class, anyone may be cold-called to present any question at the board, and that recitation is the participation grade.* --- ## Assumed pre-class reading - L23 wrap-up (reticle vs imaging seekers, IRST, the passive detection range rule) - The Jupyter Book Reading page for L24 — the four ways to attack the optical track, flare seduction and pre-emptive tactics, the IRCCM cue triad, DIRCM, and design-level signature suppression. --- ## Quiz questions (5 items, ~5 minutes) **Q1.** (Multiple choice) In a **seduction** flare engagement, the flare defeats a reticle seeker by: - [ ] (a) Physically blocking the seeker's view of the aircraft - [ ] (b) Out-shining the aircraft in the seeker's band while both are still inside the tracking gate, then dragging the gate away as they separate - [ ] (c) Burning at exactly the aircraft's temperature so the seeker cannot tell them apart - [ ] (d) Overloading the seeker's detector so it must be replaced --- **Q2.** (Multiple choice) Which pre-emptive flare tactic forces the shooter to engage **many credible targets at once**? - [ ] (a) Seduction - [ ] (b) Distraction - [ ] (c) Dilution - [ ] (d) Optical break lock --- **Q3.** (Short answer) Name **two of the three IRCCM cues** a modern seeker uses to reject a conventional flare, and state in a few words what each cue looks for. --- **Q4.** (Multiple choice) A **DIRCM** system defeats an IR seeker by: - [ ] (a) Launching an expendable decoy toward the missile - [ ] (b) Cooling the aircraft's exhaust so the seeker loses signal - [ ] (c) Shining a modulated laser into the seeker's optics to feed it false tracking error and break its lock - [ ] (d) Broadcasting a radio jamming waveform at the missile's uplink --- **Q5.** (Multiple choice) Why does **signature suppression** (exhaust mixing, nozzle masking, low-emissivity finishes) remain the foundation of IR survivability even for aircraft that carry flares or DIRCM? - [ ] (a) It reduces the in-band intensity $J$, shrinking every seeker's detection and launch range before any engagement begins - [ ] (b) It makes flares burn longer once dispensed - [ ] (c) It is required for the DIRCM laser to function - [ ] (d) It only matters at night, when other IRCM do not work