We’re seeking a Modeling & Simulation Engineer to develop high-fidelity environmental and target signature models used in a real-time hardware-in-the-loop (HIL) facility. You will create models that generate realistic stimuli – e.g., background environment, clutter, propagation effects, and target returns – so that sensors and mission systems can be exercised under repeatable, configurable, and operationally relevant scenarios.

This role is a strong fit for a Physics or Mathematics-based engineer who enjoys translating theory into performant code, balancing model fidelity with computational constraints to meet real-time execution requirements.

Pay Range $97,000 - $169,000

The pay range for this position is a general guideline only and not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of job, education, experience, knowledge, skills, and abilities, as well as internal equity, alignment with market data, geographic location, and any applicable laws.

• Develop environment and target signature models for real-time simulation (e.g., propagation effects, background/clutter, target scattering/returns, sensor phenomenology as applicable).
• Implement and optimize algorithms to run in real-time constraints for HIL execution (latency, throughput, determinism).
• Design model interfaces and data products for integration into a HIL testbed (APIs, message formats, timing/synchronization, scenario control).
• Validate models against truth data, analytical benchmarks, or lab measurements; quantify accuracy and uncertainty where appropriate.
• Build tools and workflows for scenario generation and parameter sweeps; support repeatable test campaigns and regression testing.
• Integrate models into a HIL facility: coordinate with hardware, software, and test teams; support bring-up, troubleshooting, and test execution.
• Document model assumptions, limitations, tunable parameters, and verification results; produce clear technical reports and presentations.
• Support customer demonstrations and test events by configuring scenarios, monitoring execution, and providing rapid analysis of outputs.

• BS/MS (or PhD) in Physics, Applied Mathematics, Mathematics, Electrical Engineering, or related discipline with strong modeling focus.
• Mininum 2 years experience.
• Strong programming skills (Python required; C/C++ preferred for performance-critical components)
• Experience implementing numerical methods, stochastic models, and/or signal/phenomenology models in code.
• Ability to balance model fidelity and performance for real-time execution; familiarity with profiling and optimization.
• Experience with verification/validation methods and disciplined documentation of assumptions and limitations.
• Ability to collaborate across disciplines and communicate complex technical concepts clearly.

Nice to have

• 5 years experience.
• Experience with real-time simulation, HIL facilities, or closed-loop test environments (deterministic scheduling, low-latency pipelines).
• Experience modeling sensor signatures and environments (radar/EO/IR/acoustic/RF) or domain-specific phenomenology.
• Familiarity with physics-based modeling approaches (e.g., scattering, propagation, atmospheric effects, terrain/clutter, multipath).Experience with MATLAB/Simulink or other modeling toolchains; ability to translate models into production code.
• Comfort working with recorded data sets and measurement equipment outputs; basic signal processing knowledge.

Security requirements

• Citizenship: U.S. citizenship required
• Clearance: Active Secret required

i3 is a technically diverse, 100% team member owned business, headquartered in Huntsville, Alabama specializing in missile and aviation systems engineering and logistic services, electronic warfare and electromagnetic effects analysis, UAS system integration and flight operations, full lifecycle C5ISR engineering services, cybersecurity and IT/IA innovative solutions and virtual training, simulation & serious game development and implementation. We have established a broad offering of products and capabilities collectively providing decades of experience supporting the full complement of DoD military services, Missile Defense Agency, National Aeronautics and Space Administration, and a variety of other Government organizations and private industry customers.

Perks of being a team member owner include:

• Long-term financial security
• Higher job satisfaction
• Greater job security
• Personal and professional growth
• Great company culture

Other outstanding benefits:

• Excellent insurance coverage
• 401(k) match
• Generous PTO
• Health and wellness incentives
• Tuition and certification reimbursement
• Countless opportunities to give back to the community through i3 Cares

We work hard. We compete hard. We play hard. Apply now to join us!