L31 Pre-flight

L31 Pre-flight#

Block 4: Aircraft Survivability and Mission Planning — Lesson 31: Survivability and the PK Chain Work this before L31. 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#

  • L1’s kill chain (Detect → Track → Identify → Engage → Kill) and the idea that breaking any one link saves the aircraft.

  • The Jupyter Book Reading page for L31 — Ball’s split of survivability into susceptibility \(P_H\) and vulnerability \(P_{K|H}\), the chain as a product of conditional probabilities, Ball’s two toolkits, \(P_S = \prod_i (1 - P_{K,i})\) across independent encounters, and additive risk \(r = -\ln P_S\).

Quiz questions (5 items, ~5 minutes)#

Q1. (Mark all that apply) A B-21 flies the same route against the same air defense. Mark every change below that reduces its susceptibility (\(P_H\), the chance it is hit) rather than its vulnerability.

  • [ ] (a) A radar-warning receiver that tells the crew a SAM has locked on, in time to turn away

  • [ ] (b) Two hydraulic systems routed down opposite sides of the fuselage

  • [ ] (c) A flare dispenser that seduces an IR seeker in its terminal phase

  • [ ] (d) Foam in the fuel tanks that keeps a fragment hit from igniting the fuel vapor

  • [ ] (e) An escort that destroys the SAM’s engagement radar before the ingress

Q2. (Mark all that apply) Same aircraft, same route. Mark every change below that reduces its vulnerability (\(P_{K|H}\), the chance that a hit kills it).

  • [ ] (a) Moving the flight-control computers away from the fuel tanks and the engine bays

  • [ ] (b) Radar-absorbing material applied to the engine inlet lips

  • [ ] (c) An engine-bay fire detector wired to an automatic extinguisher

  • [ ] (d) An armor plate between the most likely hit direction and the crew station

  • [ ] (e) A self-protection jammer that walks the tracking radar’s range gate off the aircraft

Q3. (Multiple choice) A route meets three SAM sites, and each fires one independent shot with \(P_K = 0.10\), \(0.25\) and \(0.05\). The mission’s survival probability \(P_S\) is:

  • [ ] (a) 0.600

  • [ ] (b) 0.641

  • [ ] (c) 0.750

  • [ ] (d) 0.867

Q4. (Multiple choice) L34 will plan routes with a shortest-path search that minimizes a sum of per-encounter costs. Why should each encounter’s cost be \(r_i = -\ln(1 - P_{K,i})\) rather than \(P_{K,i}\) itself?

  • [ ] (a) Its sum is exactly \(-\ln P_S\), so the route with the least total cost is the most survivable

  • [ ] (b) It is always smaller than \(P_{K,i}\), so the planner cannot overstate a route’s risk

  • [ ] (c) A sum of \(P_{K,i}\) values can pass 1, and the log keeps the total cost below one

  • [ ] (d) It weights low-\(P_K\) encounters more heavily, so the planner avoids many small threats

Q5. (Short answer) For each lever, say whether it is susceptibility or vulnerability reduction, name Ball’s concept, and name the factor of \(P_K = P_D\,P_{T|D}\,P_{I|T}\,P_{H|I}\,P_{K|H}\) it shrinks: (i) a low-altitude ingress that keeps the aircraft below a SAM radar’s horizon until the last minutes of the run; (ii) replacing a hydraulic flight-control actuator with an electric one that has no fluid to leak or burn.

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