RTX Software Engineer Interview Guide

The 60-second brief

A Software Engineer at RTX (formerly Raytheon Technologies) plays a foundational role in developing, integrating, and maintaining critical software systems across aerospace and defense domains. Operating within major business units such as Raytheon, Collins Aerospace, and Pratt & Whitney, engineers work on mission-critical technologies ranging from real-time embedded flight systems, radar and signal processing algorithms, and missile defense platforms to satellite communications, avionics, and ground control systems. The software engineered here directly impacts national security, commercial aviation safety, and global defense infrastructure. As a Software Engineer at RTX, your daily contributions directly affect the reliability, performance, and security of hardware-software integrated platforms.

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

Focus areas

• Behavioral Interviews (STAR method)
• Resume Review & Project Storytelling
• Data Structures - Binary Tree

The RTX interview process

RTX candidates report 4 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

HR Phone Screening

Initial screening call to discuss background, location preferences, salary expectations, and security clearance eligibility.

What to demonstrate

• Initial screening call to discuss background, location preferences, salary expectations, and security clearance eligibility
• Depth in Behavioral Interviews (STAR method)

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.

Virtual Panel Interviews

Candidates participate in a series of video conference interviews with 2 to 5 interviewers, focusing on resume walks and technical project reviews.

What to demonstrate

• Candidates participate in a series of video conference interviews with 2 to 5 interviewers
• Focusing on resume walks and technical project reviews

How to prepare

• Answer aloud and timed: What is a virtual function in C++, why would you use it, and what is the underlying mechanism behind virtual dispatch?
• Answer aloud and timed: What is the main difference between a heap and a stack, and how do you prevent memory leaks in dynamic memory allocation?

Take-Home Assessment

Depending on the business unit, candidates may complete a take-home assessment or a live pseudocode problem-solving session.

What to demonstrate

• Depending on the business unit, candidates may complete a take-home assessment or a live pseudocode problem-solving session
• Depth in Behavioral Interviews (STAR method)

How to prepare

• Answer aloud and timed: How does a struct differ from a class in C++, and when would you choose one over the other?
• Answer aloud and timed: How do you find the least child or perform deletion operations on a Binary Search Tree (BST)?

Job Offer

Offers are typically extended rapidly following the panel interview, often within a few days to two weeks.

What to demonstrate

• Offers are typically extended rapidly following the panel interview, often within a few days to two weeks
• Depth in Behavioral Interviews (STAR method)

How to prepare

• Answer aloud and timed: Describe how a linked list is implemented from scratch, and explain how you would detect cycles or connect list nodes.
• Answer aloud and timed: What sorting algorithms offer $O(n \log n)$ performance, and how would you select an appropriate data structure for real-time lookup?

Where candidates lose points

Master the STAR Method

Structure behavioral responses clearly by outlining the Situation, Task, Action, and Result. Keep focus on your specific individual actions and technical ownership rather than general team efforts.

Know Your Resume Inside and Out

Expect panel members to pick specific lines from your resume and ask deep technical follow-up questions. Be ready to explain architecture choices, bugs encountered, and tools used on every project listed.

Emphasize Quality and Ethics

RTX places high emphasis on safety and quality compliance. Be prepared to discuss how you validate code quality through testing and how you handle conflicting technical opinions or test failures ethically.

If asked a technical question you do not immediately know the answer to, communicate your thought process out loud

RTX panels appreciate candidates who demonstrate logical deduction and structured problem-solving under uncertainty.

Questions & practice

What is the main difference between a heap and a stack, and how do you prevent memory leaks in dynamic memory

Medium · Object-Oriented Design & Core C/C++ Conc

What is the main difference between a heap and a stack, and how do you prevent memory leaks in dynamic memory allocation?

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?

How do you find the least child or perform deletion operations on a Binary Search Tree (BST)?

Medium · Data Structures & Algorithmic Problem-So

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?

Describe how a linked list is implemented from scratch, and explain how you would detect cycles or connect lis

Medium · Data Structures & Algorithmic Problem-So

Describe how a linked list is implemented from scratch, and explain how you would detect cycles or connect list nodes.

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?

What sorting algorithms offer $O(n \log n)$ performance, and how would you select an appropriate data structur

Medium · Data Structures & Algorithmic Problem-So

What sorting algorithms offer $O(n \log n)$ performance, and how would you select an appropriate data structure for real-time lookup?

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?

What is the difference between a for loop and a do-while loop, and how do compiler optimizations impact lo

Medium · Data Structures & Algorithmic Problem-So

What is the difference between a for loop and a do-while loop, and how do compiler optimizations impact loop execution?

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?

What is the difference between threads and processes, and how do you handle synchronization and multithreading

Medium · Systems Engineering & Domain-Specific Kn

What is the difference between threads and processes, and how do you handle synchronization and multithreading safely?

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?

Find version gaps and relay lag with window functions

Medium · window functions · event tables · frame semantics

outbox_event holds event_id, aggregate_type, aggregate_id, aggregate_version, event_type, payload, status ('pending','published','dead'), attempts, created_at, published_at. A projection is missing rows and you must decide whether the relay skipped events or the consumer dropped them. Write three queries over the last seven days: one listing every aggregate_id whose published aggregate_version sequence has a hole, one giving per-day counts with a running total, and one returning the newest published event per aggregate. For each, say where the window function is evaluated relative to WHERE and LIMIT. PostgreSQL 16.

Approach

1. Gaps: compute lead(aggregate_version) OVER (PARTITION BY aggregate_id ORDER BY aggregate_version) in a subquery, then filter next_version <> aggregate_version + 1 in the outer query. Window functions are evaluated after WHERE, GROUP BY and HAVING and before the outer ORDER BY and LIMIT, so the predicate cannot sit in the same WHERE clause and PostgreSQL 16 has no QUALIFY.
2. Say what the seven-day filter does to the answer: it truncates every partition, so the first row per aggregate has no predecessor inside the window and a hole spanning the boundary is invisible. Widen the window, or join to resource.version as the authority for the true maximum.
3. Running total: SELECT date_trunc('day', created_at) AS d, count() AS n, sum(count()) OVER (ORDER BY date_trunc('day', created_at) ROWS UNBOUNDED PRECEDING). An aggregate inside a window call is legal because grouping runs before windowing. The grouping key is unique per row here so ROWS and RANGE agree, but write the frame anyway — over ungrouped rows with tied timestamps the default RANGE frame pulls in every peer row and the total jumps.
4. Newest per aggregate: DISTINCT ON (aggregate_id) ... ORDER BY aggregate_id, aggregate_version DESC is the cheap PostgreSQL-only form when an index matches that order; row_number() OVER (PARTITION BY aggregate_id ORDER BY aggregate_version DESC) = 1 is the portable form and needs a subquery for the same evaluation-order reason as the gap query.

Follow-up

• Relay failover redelivers events. Does a duplicate break the gap query, and how would you detect one from this table alone?
• Turn the gap check into a continuous monitor rather than a query someone runs after an incident. What does it watch?

Explain why the owner filter ignores the listing index

Medium · composite index · query plans · sort elimination

The only index on resource is (tenant_id, status, updated_at DESC, resource_id DESC). A new endpoint returns one user's resources across all statuses, newest created first: WHERE tenant_id = $1 AND owner_user_id =$2 ORDER BY created_at DESC LIMIT 20. On a tenant with 2M rows it takes 900 ms and EXPLAIN shows a sort above a large scan. Explain precisely why the existing index cannot serve it, give the index that can, and state which of these the new index still will not help: owner_user_id alone across tenants; the same query ordered by updated_at. PostgreSQL 16.

Approach

1. Separate the two jobs an index does. For filtering, a composite btree is seekable only on a left prefix, so with no predicate on status the scan can at best range over tenant_id and test owner_user_id per row; PostgreSQL 16 has no btree skip scan to jump the unconstrained column.
2. For ordering, the index is sorted by (status, updated_at) within a tenant and not by created_at, so the LIMIT cannot stop early: every matching row is read and then sorted. That is the 'Sort Method: top-N heapsort' line, and it is why the plan reads 2M rows to answer with 20.
3. Derive the replacement from the access path — equality, equality, then the ordering column: CREATE INDEX CONCURRENTLY ON resource (tenant_id, owner_user_id, created_at DESC). The scan seeks to the (tenant, owner) range and walks 20 entries in order, so the Sort node disappears along with the row-read.
4. Treat INCLUDE (title, status) as conditional, not free. An index-only scan still visits the heap for any row whose page is not marked all-visible, so on a table taking 1.2k writes/second the win depends on autovacuum keeping the visibility map current, and the wider index costs more on every insert.

Follow-up

• 90% of rows are status='active'. Would a partial index WHERE status = 'active' change your answer, and for which of the three queries?
• A dashboard runs this for 40 owners in one page load. What changes about the design?

What are the four core principles of Object-Oriented Design, and how do you apply them in C++?

Medium · Object-Oriented Design & Core C/C++ Conc

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?

Explain the difference between polymorphism and inheritance with a practical example.

Medium · Object-Oriented Design & Core C/C++ Conc

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 a virtual function in C++, why would you use it, and what is the underlying mechanism behind virtual d

Medium · Object-Oriented Design & Core C/C++ Conc

What is a virtual function in C++, why would you use it, and what is the underlying mechanism behind virtual dispatch?

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?

How does a struct differ from a class in C++, and when would you choose one over the other?

Medium · Object-Oriented Design & Core C/C++ Conc

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?

Can you describe the software development V-model and explain how software engineering integrates with systems

Medium · Systems Engineering & Domain-Specific Kn

Can you describe the software development V-model and explain how software engineering integrates with systems engineering milestones?

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?

Explain the difference between an abstract class and an interface, and when you would use each in software arc

Medium · Systems Engineering & Domain-Specific Kn

Explain the difference between an abstract class and an interface, and when you would use each in software architecture.

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

Explain constructive interference and inter-symbol interference in digital communications or radar signal proc

Medium · Systems Engineering & Domain-Specific Kn

Explain constructive interference and inter-symbol interference in digital communications or radar signal processing.

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?

How do you determine the stability of a linear time-invariant (LTI) system using its eigenvalues?

Medium · Systems Engineering & Domain-Specific Kn

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?

Describe your technical approach to debugging a dynamic memory corruption or stack overflow issue.

Medium · Data Structures & Algorithmic Problem-So

Approach

1. Establish what changed and when, before forming any theory.
2. Pick a bisection that eliminates candidates whichever way it turns out.
3. Check the instrumentation before believing the symptom.
4. Separate the trigger from the cause; the deploy is rarely the bug.

Follow-up

• What would you look at first, and what would it rule out?
• How would you tell a cause from a coincidence here?

Suggested practice checklist

Built from the rounds and topics RTX candidates report.

Day 1 — Map the RTX loop

• Write out the reported sequence: HR Phone Screening, Virtual Panel Interviews, Take-Home Assessment, Job Offer.
• 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 4 reported rounds, with the weakest marked.

Day 2 — Work Behavioral Interviews (STAR method)

• Spend the session on Behavioral Interviews (STAR method), which RTX candidates report being tested on.
• Write one worked example in Behavioral Interviews (STAR method) and time yourself on it.

Deliverable: One timed worked example in Behavioral Interviews (STAR method).

Day 3 — Work Resume Review & Project Storytelling

• Spend the session on Resume Review & Project Storytelling, which RTX candidates report being tested on.
• Write one worked example in Resume Review & Project Storytelling and time yourself on it.

Deliverable: One timed worked example in Resume Review & Project Storytelling.

Day 4 — Work Data Structures - Binary Tree

• Spend the session on Data Structures - Binary Tree, which RTX candidates report being tested on.
• Write one worked example in Data Structures - Binary Tree and time yourself on it.

Deliverable: One timed worked example in Data Structures - Binary Tree.

Day 5 — Answer out loud: Object-Oriented Design & Core C/C++ Concepts

• Answer aloud, timed: What are the four core principles of Object-Oriented Design, and how do you apply them in C++?
• Answer aloud, timed: Explain the difference between polymorphism and inheritance with a practical example.

Deliverable: Spoken answers to 2 reported Object-Oriented Design & Core C/C++ Concepts question(s), under time.

Day 6 — Answer out loud: Data Structures & Algorithmic Problem-Solving

• Answer aloud, timed: How do you find the least child or perform deletion operations on a Binary Search Tree (BST)?
• Answer aloud, timed: Describe how a linked list is implemented from scratch, and explain how you would detect cycles or connect list nodes.

Deliverable: Spoken answers to 2 reported Data Structures & Algorithmic Problem-Solving question(s), under time.

Day 7 — Answer out loud: Systems Engineering & Domain-Specific Knowledge

• Answer aloud, timed: Can you describe the software development V-model and explain how software engineering integrates with systems engineering milestones?
• Answer aloud, timed: Explain the difference between an abstract class and an interface, and when you would use each in software architecture.

Deliverable: Spoken answers to 2 reported Systems Engineering & Domain-Specific Knowledge question(s), under time.

Behavioural preparation

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

Describe a time when you encountered a major setback during a technical project and how you managed it.

Medium · Behavioral & Situational Judgment

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 handle a scenario where a team member is falling behind or where there is a strong technical disagr

Medium · Behavioral & Situational Judgment

How do you handle a scenario where a team member is falling behind or where there is a strong technical disagreement on design direction?

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 situation where a manager or stakeholder asked you to ignore or bypass bad test results—how di

Medium · Behavioral & Situational Judgment

Tell me about a situation where a manager or stakeholder asked you to ignore or bypass bad test results—how did you respond?

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 approach familiarizing yourself with a massive, legacy code base when onboarding onto a new program

Medium · Behavioral & Situational Judgment

How do you approach familiarizing yourself with a massive, legacy code base when onboarding onto a new program?

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?

Why do you specifically want to build software at RTX compared to other aerospace or commercial technology com

Medium · Behavioral & Situational Judgment

Why do you specifically want to build software at RTX compared to other aerospace or commercial technology companies?

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?