A Software Engineer at United Airlines plays a critical role in keeping one of the world’s largest aviation networks running smoothly. Technology at United Airlines is not just a supporting function; it is the core engine that drives flight operations, crew scheduling, safety compliance, customer-facing digital platforms, and complex logistics. Engineers here build and maintain the highly scalable systems that manage everything from real-time aircraft maintenance programs to complex interior configuration systems and enterprise-grade service management platforms. As a Software Engineer, your work directly impacts millions of passengers and thousands of operational staff every day. Whether you are optimizing backend services in Java or C#, designing cloud-native microservices on AWS, or writing complex database queries to track aircraft components, your code must be resilient, secure, and highly performant. The sheer scale of operations means you will tackle unique challenges in concurrent processing, real-time data streaming, and distributed systems integration. This role requires a balance of strong technical fundamentals and deep operational empathy. Candidates who succeed at United Airlines are those who do not just write code in a vacuum, but who understand how their software fits into the broader operational ecosystem—ensuring that flights take off safely, on time, and with the highest level of efficiency.
HR/Recruiter Screen
reportedInitial screening focusing on your background, career goals, and alignment with the role's requirements.
What to demonstrate
- Initial screening focusing on your background, career goals, and alignment with the role's requirements
- Depth in Data Structures
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 Assessment
reportedComplete an online technical assessment or preliminary technical screening call testing core data structures, algorithms, and SQL proficiency.
What to demonstrate
- Complete an online technical assessment or preliminary technical screening call testing core data structures, algorithms, and SQL proficiency
- Depth in Data Structures
How to prepare
- Answer aloud and timed: Explain memory management in your primary language. How does the garbage collector optimize heap memory?
- Answer aloud and timed: How do you handle multi-threading and prevent race conditions when processing concurrent data?
Core Technical Rounds
reportedEngage in highly interactive rounds with panels of senior engineers, architects, and hiring managers.
What to demonstrate
- Engage in highly interactive rounds with panels of senior engineers, architects, and hiring managers
- Depth in Data Structures
How to prepare
- Answer aloud and timed: Walk through a recursive function you have written and explain how to optimize it to prevent stack overflow.
- Answer aloud and timed: Explain ACID properties in relational databases and why they are critical for transactional systems.
Behavioral Questions
reportedAnswer in-depth questions about your resume projects, system design scenarios, and behavioral situations.
What to demonstrate
- Answer in-depth questions about your resume projects, system design scenarios, and behavioral situations
- Depth in Data Structures
How to prepare
- Prepare three examples from your own work, each with a decision you made and an outcome you can quantify.
- Re-read the description of the behavioral questions above and write down what you would ask to confirm before it.
PracHub editorial advice for the preparation topics above.
Master your resume details
One of the most common pieces of feedback from United Airlines candidates is that interviewers go through resumes with a fine-tooth comb. Be prepared to explain the architecture, design decisions, and technology choices for every project you have listed.
Do not list technologies on your resume that you cannot discuss in-depth
If you list AWS, Docker, or Kubernetes, expect deep questions about how you configured, deployed, and monitored those services in production.
Prepare for system monitoring and support questions
Because United Airlines operates around the clock, engineers are highly valued if they understand how to keep systems healthy. Brush up on your knowledge of logging, live monitoring tools, and how you would diagnose a production failure.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Explain the four pillars of Object-Oriented Programming (OOP) and provide real-world coding examples of how yo
Explain the four pillars of Object-Oriented Programming (OOP) and provide real-world coding examples of how you have applied them.
Approach
- Say what the runtime actually does before reasoning about the code.
- Name what is shared across threads and what owns each piece of state.
- Identify the window where an invariant is briefly untrue.
- 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 are the primary differences between the main programming languages on your resume (e.g., Java vs. C#)?
What are the primary differences between the main programming languages on your resume (e.g., Java vs. C#)?
Approach
- Say what the runtime actually does before reasoning about the code.
- Name what is shared across threads and what owns each piece of state.
- Identify the window where an invariant is briefly untrue.
- 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 memory management in your primary language. How does the garbage collector optimize heap memory?
Explain memory management in your primary language. How does the garbage collector optimize heap memory?
Approach
- Say what the runtime actually does before reasoning about the code.
- Name what is shared across threads and what owns each piece of state.
- Identify the window where an invariant is briefly untrue.
- 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 handle multi-threading and prevent race conditions when processing concurrent data?
How do you handle multi-threading and prevent race conditions when processing concurrent data?
Approach
- Say what the runtime actually does before reasoning about the code.
- Name what is shared across threads and what owns each piece of state.
- Identify the window where an invariant is briefly untrue.
- 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?
Walk through a recursive function you have written and explain how to optimize it to prevent stack overflow.
Walk through a recursive function you have written and explain how to optimize it to prevent stack overflow.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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?
Explain ACID properties in relational databases and why they are critical for transactional systems.
Explain ACID properties in relational databases and why they are critical for transactional systems.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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?
When would you choose a NoSQL database over a relational database for an enterprise-level service?
When would you choose a NoSQL database over a relational database for an enterprise-level service?
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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?
Given an array of integers, write an algorithm to detect if a specific number is a perfect square without usin
Given an array of integers, write an algorithm to detect if a specific number is a perfect square without using built-in library functions.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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?
Implement a function to generate the Fibonacci sequence up to $N$ terms, discussing both iterative and recursi
Implement a function to generate the Fibonacci sequence up to $N$ terms, discussing both iterative and recursive time complexities.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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?
Solve the classic puzzle: Three Ants and a Triangle. What is the probability that they do not collide if they
Solve the classic puzzle: Three Ants and a Triangle. What is the probability that they do not collide if they start walking along the edges?
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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?
Walk through how you would detect and remove a loop in a singly linked list.
Walk through how you would detect and remove a loop in a singly linked list.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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 a situation where you had to work with ambiguous requirements. How did you structure your approach?
Describe a situation where you had to work with ambiguous requirements. How did you structure your approach?
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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 complex SQL query utilizing joins, aggregations, and window functions to retrieve specific operational
Write a complex SQL query utilizing joins, aggregations, and window functions to retrieve specific operational datasets.
Approach
- Name the grain you start from and join outward from it.
- Check whether any join is one-to-many before aggregating, or the sums inflate.
- Say which index the query would use, and what makes it unusable.
- 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?
How do you optimize a slow-running SQL query? Explain the role of indexing and execution plans.
How do you optimize a slow-running SQL query? Explain the role of indexing and execution plans.
Approach
- Name the grain you start from and join outward from it.
- Check whether any join is one-to-many before aggregating, or the sums inflate.
- Say which index the query would use, and what makes it unusable.
- 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?
How do you design and secure microservices communicating over asynchronous networks?
How do you design and secure microservices communicating over asynchronous networks?
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- 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 the components of the ELK Stack (Elasticsearch, Logstash, Kibana) and how you would use them for live
Explain the components of the ELK Stack (Elasticsearch, Logstash, Kibana) and how you would use them for live application monitoring.
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- 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?
Walk me through the architecture of a significant project on your resume. Why did you choose that specific tec
Walk me through the architecture of a significant project on your resume. Why did you choose that specific tech stack?
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- 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?
One log partition stops advancing while the others drain
Search results for a subset of tenants are hours stale; the rest are current. The projection consumer reports lag of zero on 15 of 16 partitions and 400,000 on one. Its error rate is flat and its CPU is idle. outbox_event has no pending rows older than a second, so the relay has published everything it holds. Identify the mechanism, give the ordered checks, and state what you do in the first ten minutes versus what you change permanently.
Approach
- Read the lag distribution first. A slow consumer lags everywhere; zero on fifteen partitions and 400,000 on one is not throughput. Idle CPU on the stuck partition means the consumer is not advancing its offset at all, which points at one message it cannot get past rather than at a rate problem.
- Exonerate the producer before touching the consumer. No pending outbox rows older than a second means the relay published, so the event exists in the log. This separates never sent from sent and never applied, which are different code paths and usually different owners.
- Read the message at the stuck offset and the handler's log lines for its event_id. A flat error rate with no progress has two explanations and you must distinguish them: the handler is throwing and the retry loop is swallowing it, or the handler is blocking on something and never returning. Idle CPU with no error lines favours the second.
- Mitigate before diagnosing further. Move the offending event to a dead-letter store and commit the offset past it. Adding consumers does nothing here, because a partition is consumed by exactly one member of the group, and the blast radius is every aggregate hashed to that partition, not only the aggregate that produced the bad event.
Follow-up
- The dead-lettered event carried aggregate_version 7 and the projection had applied 6. What must the replay do differently if 8 and 9 landed in the meantime?
- How do you show staleness to the user while the partition is behind, given the API already returns the projection's watermark?
Built from the rounds and topics United Airlines candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the United Airlines loop
- Write out the reported sequence: HR/Recruiter Screen, Technical Assessment, Core Technical Rounds, Behavioral Questions.
- 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.
02Work Data Structures
- Spend the session on Data Structures, which United Airlines candidates report being tested on.
- Write one worked example in Data Structures and time yourself on it.
Deliverable: One timed worked example in Data Structures.
03Work Algorithms
- Spend the session on Algorithms, which United Airlines candidates report being tested on.
- Write one worked example in Algorithms and time yourself on it.
Deliverable: One timed worked example in Algorithms.
04Work SQL (Querying)
- Spend the session on SQL (Querying), which United Airlines candidates report being tested on.
- Write one worked example in SQL (Querying) and time yourself on it.
Deliverable: One timed worked example in SQL (Querying).
05Answer out loud: Object-Oriented Programming & Language Theory
- Answer aloud, timed: Explain the four pillars of Object-Oriented Programming (OOP) and provide real-world coding examples of how you have applied them.
- Answer aloud, timed: What are the primary differences between the main programming languages on your resume (e.g., Java vs. C#)?
Deliverable: Spoken answers to 2 reported Object-Oriented Programming & Language Theory question(s), under time.
06Answer out loud: Databases & Query Optimization
- Answer aloud, timed: Explain ACID properties in relational databases and why they are critical for transactional systems.
- Answer aloud, timed: Write a complex SQL query utilizing joins, aggregations, and window functions to retrieve specific operational datasets.
Deliverable: Spoken answers to 2 reported Databases & Query Optimization question(s), under time.
07Answer out loud: Problem Solving & Algorithms
- Answer aloud, timed: Given an array of integers, write an algorithm to detect if a specific number is a perfect square without using built-in library functions.
- Answer aloud, timed: Implement a function to generate the Fibonacci sequence up to $N$ terms, discussing both iterative and recursive time complexities.
Deliverable: Spoken answers to 2 reported Problem Solving & Algorithms question(s), under time.
Expand any day for tasks and deliverables. Your progress is saved on this device.
Behavioural rounds judge the decision you made and what it cost.
What is a distributed cache, and how do you handle cache invalidation in a high-traffic environment?
What is a distributed cache, and how do you handle cache invalidation in a high-traffic environment?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- 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?
Walk through your experience deploying applications to AWS and managing environment-specific configurations.
Walk through your experience deploying applications to AWS and managing environment-specific configurations.
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- 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 when you had to debug a critical issue in production under tight time constraints.
Describe a time when you had to debug a critical issue in production under tight time constraints.
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- 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 when you disagreed with a technical decision made by a senior engineer or architect. How
Tell me about a time when you disagreed with a technical decision made by a senior engineer or architect. How did you resolve it?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- 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?
- 01
What is a distributed cache, and how do you handle cache invalidation in a high-traffic environment?
- 02
Walk through your experience deploying applications to AWS and managing environment-specific configurations.
- 03
Describe a time when you had to debug a critical issue in production under tight time constraints.
- 04
Tell me about a time when you disagreed with a technical decision made by a senior engineer or architect. How did you resolve it?
How technical are the interviews at United Airlines?
The interviews are highly technical but very practical. While you will face questions on data structures, algorithms, and system design, the focus is heavily on how you apply these concepts to real-world scenarios and your past projects. Expect in-depth questions about the technologies listed on your resume rather than purely theoretical academic puzzles.
United Airlines Software Engineer candidate reports ↗What is the typical timeline from the first screen to an offer?
The entire process usually takes between three to six weeks. However, candidate experiences show that timelines can sometimes vary due to scheduling availability, especially during peak hiring seasons or on-campus recruitment events.
United Airlines Software Engineer candidate reports ↗How heavily does United Airlines use the STAR method?
Very heavily, especially in managerial, behavioral, and panel interviews. United Airlines values structured communication. You should prepare your professional stories in advance, ensuring you clearly highlight the Situation, Task, Action you took, and the quantifiable Result of your efforts.
United Airlines Software Engineer candidate reports ↗Can I choose my preferred programming language for the coding assessments?
Yes, for general coding assessments and algorithmic questions, you can typically use the language you are most comfortable with. However, for team-specific technical rounds (such as a dedicated Java or.NET developer role), you will be expected to demonstrate deep technical proficiency in that specific language and its ecosystem.
United Airlines Software Engineer candidate reports ↗Does United Airlines offer hybrid or remote work options for Software Engineers?
This depends on the specific team and location. Many engineering roles based out of major hubs like Chicago, IL, and Houston, TX, operate on a hybrid schedule, requiring some in-office collaboration days. Be sure to clarify the exact expectations for your target role with your recruiter during the initial call.
United Airlines Software Engineer candidate reports ↗What topics does United Airlines test in interviews?
United Airlines interviews most often cover SQL, Python, Problem Solving, Data Structures, and Algorithms. The exact emphasis depends on the specific role you apply for.
United Airlines Software Engineer candidate reports ↗Sources & methodology 3 sources ↗
Official role evidence, timestamped platform data and clearly labeled preparation advice.
- 01United Airlines Software Engineer candidate reports ↗
Company-reported rounds, questions and FAQ.
candidate · Accessed 2026-09-22 - 02PracHub Software Engineer practice ↗
PracHub practice material, not company-reported.
platform · Accessed 2026-09-22 - 03PracHub preparation framework ↗
PracHub preparation guidance.
platform · Accessed 2026-09-22
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