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AERMOR Software Engineer Interview Guide

AERMOR Software Engineer interview guide: reported rounds, questions and how candidates describe the process.

The 60-second brief

At AERMOR, a Software Engineer is more than just a coder; you are a critical contributor to national defense and operational readiness. You will work on mission-critical systems that directly support the United States Government, including the U.S. Navy and Air Force. Your work ensures that complex weapon systems, navigation tools, and C4ISR (Command, Control, Communications, Computers, Intelligence, Surveillance, and Reconnaissance) platforms function reliably under the most demanding conditions. The role often bridges the gap between pure software development and systems engineering. Whether you are conducting Independent Verification & Validation (IV&V) to ensure code meets rigorous safety standards, developing hybrid software-hardware interfaces for navigation systems, or building secure.NET applications for data management, your output has real-world consequences.

This guide is scoped to a Software Engineer candidate at AERMOR.

Focus areas

  • Mechanical Engineering
  • Systems Engineering
  • Model-Based Systems Engineering (MBSE)

The AERMOR interview process

AERMOR candidates report 3 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Recruiter Screening

Initial screening to verify background, clearance status, and alignment with contract requirements.

What to demonstrate

  • Initial screening to verify background, clearance status, and alignment with contract requirements
  • Depth in Mechanical Engineering

How to prepare

  • Be able to walk your CV end to end in two minutes, and say why this company specifically.
  • Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.

Technical Interview

Interview with a Hiring Manager or Lead Engineer focusing on practical engineering knowledge and experience.

What to demonstrate

  • Interview with a Hiring Manager or Lead Engineer focusing on practical engineering knowledge and experience
  • Depth in Mechanical Engineering

How to prepare

  • Answer aloud and timed: "How do you optimize a SQL query that is slowing down a real-time reporting dashboard?"
  • Answer aloud and timed: "Write a function to parse a specific data format (e.g., XML or JSON) and validate its integrity."

Panel Interview

In-depth discussion with the team assessing problem-solving abilities in real-world scenarios relevant to the job.

What to demonstrate

  • In-depth discussion with the team assessing problem-solving abilities in real-world scenarios relevant to the job
  • Depth in Mechanical Engineering

How to prepare

  • Answer aloud and timed: "How do you ensure requirements traceability throughout the development lifecycle?"
  • Answer aloud and timed: "If you find a critical bug during the final phase of testing, how do you handle it vis-à-vis the project schedule?"

Where candidates lose points

Know the Mission

AERMOR supports warfighters. During your interview, express genuine interest in the mission. Understanding that your code helps protect military personnel and assets is a powerful motivator that hiring managers look for.

Highlight "Full Lifecycle" Experience

Don't just talk about writing code. Discuss how you gathered requirements, how you designed the architecture, how you tested it, and how you maintained it. The job descriptions emphasize "cradle-to-grave" responsibility.

Brush Up on Acronyms

The DoD loves acronyms (IV&V, RTM, C4ISR, IOT&E). Familiarize yourself with the ones mentioned in the job description so you can speak the language of the interviewers comfortably.

Be Prepared for "Hybrid" Questions

Even if you are a pure software engineer, you might be asked how your software interacts with the underlying hardware or operating system. Show that you understand the system as a whole, not just your specific module.

Questions & practice

"What are the key differences between C++ and Java regarding memory management, and when would you choose one

Medium · Technical & Coding

"What are the key differences between C++ and Java regarding memory management, and when would you choose one over the other for a defense system?"

Approach

  1. Say what the runtime actually does before reasoning about the code.
  2. Name what is shared across threads and what owns each piece of state.
  3. Identify the window where an invariant is briefly untrue.
  4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

  • What happens if two callers reach this at the same time?
  • Where could this allocate more than you expect?

"Explain the concept of dependency injection in.NET applications."

Medium · Technical & Coding

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

"Write a function to parse a specific data format (e.g., XML or JSON) and validate its integrity."

Medium · Technical & Coding

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

"How do you optimize a SQL query that is slowing down a real-time reporting dashboard?"

Medium · Technical & Coding

Approach

  1. Name the grain you start from and join outward from it.
  2. Check whether any join is one-to-many before aggregating, or the sums inflate.
  3. Say which index the query would use, and what makes it unusable.
  4. Handle the rows that do not match: that is usually the actual question.

Follow-up

  • How does the query change if that join becomes one-to-many?
  • What happens to this when the table is ten times larger?

Denormalise tenant onto revisions and backfill it live

Hard · denormalisation · online migration · backfill

resource_revision (revision_id, resource_id, version, actor_user_id, change_kind, patch, request_id, created_at) has 400M rows and no tenant column; tenant_id lives only on resource. Two reads need it: a tenant-scoped audit feed ordered by created_at DESC, and an offboarding purge. Both join back to resource today. Justify adding tenant_id to resource_revision against those two reads, name the anomaly the copy introduces and the constraint that prevents it, then give the ordered migration for a live table taking 1.2k writes/second — the lock each step takes, how the backfill is batched, and where each step stops being reversible. PostgreSQL 16.

Approach

  1. Justify from the access path rather than from taste. Without the column, the audit feed either scans resource_revision by created_at and discards other tenants' rows, or resolves the tenant's resource_ids first and probes with them — both proportional to the tenant's whole history rather than to one page. With (tenant_id, created_at DESC, revision_id DESC) it is a seek that stops at 50 rows, and the purge becomes a ranged delete instead of a join.
  2. Name the cost exactly: a second copy of a fact can disagree with the first. Make the disagreement unwritable rather than documented — add UNIQUE (resource_id, tenant_id) on resource so it can serve as a foreign-key target, then FOREIGN KEY (resource_id, tenant_id) REFERENCES resource (resource_id, tenant_id) on the revision table. A revision can then only ever carry its parent's tenant.
  3. Step one, expand: ALTER TABLE resource_revision ADD COLUMN tenant_id BIGINT NULL, with no default, so it is a catalogue change and no rewrite. It still needs ACCESS EXCLUSIVE for an instant, and that instant queues behind the longest open transaction on the table while every later query queues behind it — set lock_timeout to 2s and retry rather than wait.
  4. Step two, dual-write: deploy the writer that populates tenant_id on every new revision while reads still use the join. Reversible by redeploying the previous build, because nothing reads the column yet.

Follow-up

  • The backfill is half finished and a rollback is required. What state is the table in, and what does the previous build do with a half-populated column?
  • How do you verify the backfill actually finished, given rows are still being inserted while it runs?

"How do you ensure requirements traceability throughout the development lifecycle?"

Medium · Verification & Process

Approach

  1. Clarify what is being asked and what a complete answer contains.
  2. State your assumptions explicitly before working the problem.
  3. Say what you would check first and why it is the highest-information step.
  4. Work from the requirement backwards to the design.

Follow-up

  • What assumption would you test first?
  • How would you know your answer was wrong?

"What is the most challenging integration test you have conducted, and how did you resolve the failures?"

Medium · Verification & Process

Approach

  1. Say who the caller is and what they do when the call fails halfway.
  2. Define the identity of a request so a retry cannot double-apply it.
  3. Separate accepted, pending, failed and confirmed; they are different facts.
  4. Design the error taxonomy before the success shape; callers branch on it.

Follow-up

  • What happens if the caller retries after a timeout?
  • How does a client discover it is on an old version of this contract?

Listing latency scales with page size, not with filters

Easy · n+1 · latency · query batching

The tenant listing endpoint reads resource filtered by tenant_id and status, ordered by updated_at DESC, and returns each row plus the owner's display name from app_user and the actor of that resource's latest resource_revision. p99 is 55 ms at 10 rows per page and 1.4 s at 200. Database telemetry shows 401 statements per request, each under 1 ms, and nothing in the slow-query log. Diagnose the cause and give the fix, stating the statement count per request and the p99 you expect afterwards.

Approach

  1. Read the counters before forming a theory. 401 statements for 200 rows is one driver query plus two per row, and sub-millisecond execution with an empty slow-query log rules out a bad plan. The time is round trips, which is why it is invisible in every per-query metric and scales with rows returned rather than with filter selectivity.
  2. Name the two per-row statements from their normalised text: a single-row app_user lookup by user_id, and a resource_revision lookup by resource_id ordered by version DESC LIMIT 1. Confirm by dropping those two response fields and watching the statement count fall to one. That locates the calls in the serialisation layer, not the repository.
  3. Check that the arithmetic accounts for the whole gap. Measure one round trip to the replica in isolation; 400 trips at roughly 3 ms of network plus 0.2 ms of execution is about 1.3 s on top of a 55 ms baseline, which matches. If the multiplication had fallen short, the N+1 would only be part of the story and you would keep looking.
  4. Batch both lookups. Collect owner_user_ids and resource_ids from the driver query, then issue WHERE tenant_id = $1 AND user_id = ANY($2) for the users, and PostgreSQL's SELECT DISTINCT ON (resource_id) ... WHERE resource_id = ANY($2) ORDER BY resource_id, version DESC for the latest revision, which the UNIQUE (resource_id, version) index serves directly. On an engine without DISTINCT ON, use a lateral join or a row_number window. Three statements per request at any page size.

Follow-up

  • The page size is capped at 200 today. What breaks first if it is raised to 2,000, and is it still this bug?
  • How do you stop the next N+1 from reaching production, given that no individual query is slow and the endpoint's tests pass?

Suggested practice checklist

Built from the rounds and topics AERMOR candidates report.

Day 1 — Map the AERMOR loop

  • Write out the reported sequence: Recruiter Screening, Technical Interview, Panel Interview.
  • For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.

Deliverable: A one-page map of the 3 reported rounds, with the weakest marked.

Day 2 — Work Mechanical Engineering

  • Spend the session on Mechanical Engineering, which AERMOR candidates report being tested on.
  • Write one worked example in Mechanical Engineering and time yourself on it.

Deliverable: One timed worked example in Mechanical Engineering.

Day 3 — Work Systems Engineering

  • Spend the session on Systems Engineering, which AERMOR candidates report being tested on.
  • Write one worked example in Systems Engineering and time yourself on it.

Deliverable: One timed worked example in Systems Engineering.

Day 4 — Work Model-Based Systems Engineering (MBSE)

  • Spend the session on Model-Based Systems Engineering (MBSE), which AERMOR candidates report being tested on.
  • Write one worked example in Model-Based Systems Engineering (MBSE) and time yourself on it.

Deliverable: One timed worked example in Model-Based Systems Engineering (MBSE).

Day 5 — Answer out loud: Technical & Coding

  • Answer aloud, timed: "What are the key differences between C++ and Java regarding memory management, and when would you choose one over the other for a defense system?"
  • Answer aloud, timed: "Explain the concept of dependency injection in.NET applications."

Deliverable: Spoken answers to 2 reported Technical & Coding question(s), under time.

Day 6 — Answer out loud: Verification & Process

  • Answer aloud, timed: "How do you ensure requirements traceability throughout the development lifecycle?"
  • Answer aloud, timed: "If you find a critical bug during the final phase of testing, how do you handle it vis-à-vis the project schedule?"

Deliverable: Spoken answers to 2 reported Verification & Process question(s), under time.

Day 7 — Answer out loud: Behavioral & Situational

  • Answer aloud, timed: "Tell me about a time you had to explain a complex technical risk to a non-technical stakeholder."
  • Answer aloud, timed: "Working with government contracts often involves changing requirements. How do you handle scope creep?"

Deliverable: Spoken answers to 2 reported Behavioral & Situational question(s), under time.

Behavioural preparation

Behavioural rounds judge the decision you made and what it cost.

"If you find a critical bug during the final phase of testing, how do you handle it vis-à-vis the project sche

Medium · Verification & Process

"If you find a critical bug during the final phase of testing, how do you handle it vis-à-vis the project schedule?"

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

"Describe your experience with static code analysis tools. Which ones have you used?"

Medium · Verification & Process

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

"Tell me about a time you had to explain a complex technical risk to a non-technical stakeholder."

Medium · Behavioral & Situational

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

"Working with government contracts often involves changing requirements. How do you handle scope creep?"

Medium · Behavioral & Situational

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

"Describe a time you disagreed with a senior engineer's design decision. How did you handle it?"

Medium · Behavioral & Situational

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

"How do you maintain focus and attention to detail when working on extensive documentation or compliance repor

Medium · Behavioral & Situational

"How do you maintain focus and attention to detail when working on extensive documentation or compliance reports?"

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?