# Stories by Skyscanner Engineering on Medium Stories by Skyscanner Engineering on Medium This is one page of public article previews, not the complete archive. Follow Next page to continue. Summaries are not the original full articles. ## Skyscanner's journey to effective observability DevFeed: [Skyscanner's journey to effective observability]() Original publisher: [Read original article]() Author: Skyscanner Engineering Published: 2025-03-14T10:34:23Z Content type: opinion Language: en Sources: [Stories by Skyscanner Engineering on Medium]() Topics: [observability](), [telemetry](), [Instrumentation](), [OpenTelemetry](), [Prometheus]() Tags: [data](), [engineering](), [instrumentation](), [kubernetes](), [monitoring](), [observability](), [open-source](), [opentelemetry](), [prometheus](), [telemetry](), [traces](), [tracing]() ### AI overview Skyscanner describes its journey to simplify and improve its observability platform. The article explains the limitations of its earlier mix of vendors and internal systems, and outlines goals including reducing engineer cognitive load, correlating telemetry signals, controlling data cost and quality, and adopting open standards such as OpenTelemetry. ### Source excerpt The year was 2020 and Skyscanner, like the entire travel industry, faced unprecedented challenges due to the global COVID-19 pandemic. Yet, this difficult year also provided an opportunity for introspection, prompting us to enhance our tools and processes to emerge more resilient than ever, to be the world's number one travel ally. This is where our journey to completely revolutionise our approach to observability begins. The image below shows a "simplified" view of what our internal observability platform looked like at the time. As you can see, there was some room for simplification. This platform contained a mix of specialised vendors for RUM, tracing, or synthetics, and a large number of internal systems based on open-source backends like OpenTSDB, Prometheus, or multiple ELK stacks. However, our challenges were not simply related to cost, or the complexity of running this platform with a small team. We understood that our most important problem to solve was improving the confidence of all engineers to understand and operate their services, to reliably connect more than 110 million users to over 1,200 flight, hotel and car hire partners each month. This required an observability platform that would... Reduce cognitive load and context switching for engineers, with one single platform, and one single telemetry language. Correlate traces, metrics, logs, and events, across multiple services and frameworks, from client devices all the way down to Kubernetes containers. Our components don't work in isolation, and neither should the signals we use to observe them. Optimise the cost and quality of the data produced, storing the data we need to operate our systems reliably, and no more. Meaningful, contextual data can be cheaper than low-quality, verbose data. Implement open standards to future-proof our instrumentation and transport layers, to ready our tech stack for changes in the overall industry while reducing maintenance overhead. If you know anything about observab ## How Skyscanner's Software Engineering Graduate Program Started Two Careers DevFeed: [How Skyscanner's Software Engineering Graduate Program Started Two Careers]() Original publisher: [Read original article]() Author: Skyscanner Engineering Published: 2024-09-04T08:59:32Z Content type: article Language: en Sources: [Stories by Skyscanner Engineering on Medium]() Topics: [Software Engineering](), [Development]() Tags: [careers](), [coding](), [development](), [engineering](), [experience](), [graduate-students](), [internship](), [software-engineering]() ### AI overview Gergana and Michal describe how Skyscanner's Software Engineering Graduate Program shaped their early careers. They discuss applying for internships and graduate roles, including an internship that was cancelled during the COVID-19 pandemic before Gergana later joined the graduate program. ### Source excerpt Not Sure What to Do After Graduation? Here's how Skyscanner's Grad Program kick-started our careers in tech. Hello everyone! I'm Gergana, and I joined the Software Engineering Graduate Program in 2022. I hold a degree in Mathematics and Computer Science from the University of Glasgow. And I'm Michal and like Gergana, I also joined Skyscanner in 2022. I studied Software Engineering at the University of Sheffield. Gergana & Michal We first met during the Discovery Day while interviewing for our positions, and we're delighted to have continued our journey as colleagues. Both of us were equally excited and nervous about finding our place in the tech world. We're thrilled to share our experiences with you and offer a glimpse into the Graduate Program from our perspective. Sounds interesting? Keep on reading to find out how we found it! Tracing Our Journey To Skyscanner Gergana: I was in my second year of university when I decided that Skyscanner is a company I want to work for. I was aware that the culture there is very well aligned with the idea of the perfect workplace I had in my mind and the thought of working for a travel tech company was very exciting and motivating. So, I decide to apply for an internship. I got through the coding exercise step and the culture interview and I received the great news that I am invited to the final Discovery Day stage. It was all going just the way I wanted it. Unfortunately, it so happened that this same year COVID19 reached its peak, which as we all know, was particularly damaging for the travel industry, and as a consequence, the internship got cancelled. As much of a disappointing moment that was, I knew I would keep striving to be in a company like Skyscanner one day. And so it happened. During my final year at university I learnt that Skyscanner are opening their Graduate Program again and even though I already had an offer from another big corporation, I knew where I wanted to be. So, I took my chance and went for the positio ## WISE: Skyscanner's Bayesian AB experimentation library and decision engine DevFeed: [WISE: Skyscanner's Bayesian AB experimentation library and decision engine]() Original publisher: [Read original article]() Author: Skyscanner Engineering Published: 2024-04-25T06:22:08Z Content type: article Language: en Sources: [Stories by Skyscanner Engineering on Medium]() Topics: [experiments](), [Library](), [Python](), [Statistics]() Tags: [ab-testing](), [analytics](), [bayesian-statistics](), [data-science](), [engineering](), [experiment](), [experimentation](), [practices](), [statistics](), [test]() ### AI overview This article describes WISE, Skyscanner's centralized Bayesian A/B experimentation Python library and decision engine. It explains how Skyscanner uses randomized controlled experiments and why WISE was built to reduce manual analysis, standardize methodologies, and improve consistency in experimentation practices. ### Source excerpt By Dhanush Kishore, with Jose Parreño, May Alexander, Robert Shepherd, and the Skyscanner experimentation squad At Skyscanner, product decisions are driven by experimentation. As a global leader in travel, with 110 million users every month, we rely on a data-driven approach to growing and improving our product. Product managers, engineers, and data scientists run hundreds of experiments on our in-house AB experimentation platform, Dr Jekyll, to help make decisions about what features to ship for travelers and partners. When a team develops a new feature, the next step is to run a randomized controlled experiment. Every eligible user is randomly assigned either to the test variant B, where they interact with the new feature, or to the control variant A. After running the experiment for a certain duration, we test key metrics in variant B against variant A to determine whether the feature will be beneficial if rolled out to all users. This ensures that we follow an objective, scientifically rigorous approach to making product decisions. Although we already had a strong experimentation culture and an excellent experimentation platform, we identified the following needs as we scaled our experimentation program: Reduce manual effort in analyzing experiment results: While our experimentation platform, Dr Jekyll, reported test results for various metrics in an experiment, our data analytics team had to spend a considerable amount of time interpreting the results and making a decision on what variant to ship, which was becoming a bottleneck to scaling our experimentation program Need for standardization: Different teams at Skyscanner used different approaches to AB experimentation, and inconsistencies in methodologies meant it was difficult to compare results and share learnings across teams Consistency in adherence to experimentation best practices: While many teams maintained high standards of statistical rigor, others required additional support in designing and interpr ## How a Geo Data Pipeline Bug Disrupted Skyscanner Flight Search DevFeed: [How a Geo Data Pipeline Bug Disrupted Skyscanner Flight Search]() Original publisher: [Read original article]() Author: Skyscanner Engineering Published: 2023-11-21T11:36:51Z Content type: article Language: en Sources: [Stories by Skyscanner Engineering on Medium]() Topics: [Graphs](), [data](), [dataset](), [systems](), [Kubernetes clusters]() Tags: [bug](), [data-pipeline](), [dataset](), [graph](), [issue](), [kubernetes-clusters](), [recursion](), [systems]() ### AI overview A bug in Skyscanner's geo data materialisation process made some locations their own parents, creating loops in the location hierarchy and disrupting flight search. The article explains the geo data model and the incident's technical context. ### Source excerpt How recursion brought down flight search at Skyscanner On 14th September, 2023 8:05 AM UTC (all timestamps in UTC) there was a critical bug in the output of our geo data pipeline which resulted in a number of geo locations being set as parents of themselves. This caused disruption to our service, and for this we're sorry. It gave us the opportunity to evaluate what went wrong, what we learned, and ways we could prevent a situation like this from happening again. Let's take a deep dive and explain things further. What is Geo Data? Geo data is a key dataset at Skyscanner which is used to provide systems, industry partners and travellers with a complete and accurate representation of the world. In simpler terms, any time you see an Airport, City, Region or Country used in Skyscanner, it's originating from this dataset. The most visible example across our offering can be seen when searching for flights where you will specify an airport, city or country for your journey. We use the geo data to populate origins/destinations and look for flights What was the issue? Skyscanner has been on a journey to upgrade our geo data set. At this time there are two versions, two geo models, running in parallel. Flights generally need to know about airports, cities, countries, contrary to other parts of the business where we need to model more complex relations such as districts, countries, islands, etc. Those relationships form a complex graph where locations are related to each others as parents and children. For this reason we kept our original "heritage" data set, merged it with our canonical dataset, our source of truth. We then basically generate (or reconstruct) our heritage dataset from the canonical data every day at 8am UTC. This generation is referred to as materialisation. The Materialisation Process On 14th September, a bug in the materialisation process updated some locations to be the parent of themselves. For example Scotland is now parent of Scotland. We've created a lo ## How Skyscanner's all-day video call supports collaboration and knowledge sharing DevFeed: [How Skyscanner's all-day video call supports collaboration and knowledge sharing]() Original publisher: [Read original article]() Author: Skyscanner Engineering Published: 2023-08-09T12:34:59Z Content type: opinion Language: en Sources: [Stories by Skyscanner Engineering on Medium]() Topics: [Development](), [pair\_programming](), [Programming](), [meetings]() Tags: [collaboration](), [development](), [hybrid](), [knowledge-sharing](), [meetings](), [pair-programming](), [tech](), [virtual-office]() ### AI overview An employee describes how Skyscanner's hybrid team uses an all-day video call as a virtual office. The call helps colleagues across UK cities collaborate, share knowledge, support training, and participate in mob or pair programming. ### Source excerpt by Anthony Byledbal In the virtual office -- iStock Note: At Skyscanner, our teams work using a hybrid model. When not in the office, we want optimise our experience and keep close connection with our team members Video calls are usually meetings. An invitation is sent to participants and, on the scheduled day and time, all join for a limited period of time. However, in my team at Skyscanner, we as a team have decided to take a step further by introducing an all-day-long video call. The operating instructions are short: the first person to start its day, starts the call; the last person to finish, closes the call. This online tool has proven very successful with regards to employee collaboration, training enhancement, boosting morale and overall sense of engagement and positive team spirit. I was not used to working this way, but very quickly I have noticed the positive impact it had on me and my development. Before changing career from archaeology and moving to IT, I was unfamiliar with different kinds of online tools used in a working environment. I naively interpreted them as a poor management: I thought it was a way to track what me and my colleagues were doing. However, my experience in joining this call proved me wrong. Members of my squad created this online headquarter to connect their colleagues located across different cities around the United Kingdom in hope of improving communication, morale and collaboration within the team. A Shared Working Environment The call brings colleagues together. It is our virtual office where we feel less apart from each other. More importantly, this online space facilitates our daily work and knowledge sharing. It is good to see more experienced colleagues coding. Sharing screens is something our team does all day long, it immerses everyone into the code. From new joiners to senior engineers, everyone values this precious time because it allows us to ask questions and rise concerns. Most of the time, this provides us with an ## Building systems at scale: how Skyscanner approaches engineering design reviews DevFeed: [Building systems at scale: how Skyscanner approaches engineering design reviews]() Original publisher: [Read original article]() Author: Skyscanner Engineering Published: 2022-10-31T10:04:46Z Content type: opinion Language: en Sources: [Stories by Skyscanner Engineering on Medium]() Topics: [Architecture & Design](), [systems](), [Web]() Tags: [design](), [engineering](), [review](), [scale](), [systems](), [teams]() ### AI overview This article explains how Skyscanner uses engineering design reviews to peer-review changes from small code modifications to system designs. The process uses structured documents to establish shared context, align stakeholders, gather feedback, and surface incorrect assumptions across more than 80 engineering teams. ### Source excerpt By Tom Butterwith, Engineering Manager Designing systems at scale can be a daunting task at the best of times and when you add in the complexity of managing stakeholders, the whole process can get complicated fast. One of our engineering principles at Skyscanner is that we peer-review every change and we apply this principle to everything from one-line code changes to system design. We accomplish this by conducting a design review: a process centered around a document capturing the what, why, and how of a problem and its proposed solution. What are design reviews, and why do we use them? When designing systems, there are a few challenges we try to overcome with our design review process. The first is developing a shared context. In order to provide appropriate feedback, we need to ensure that everyone reading the document understands the "why" and the "what" of the problem. The "why" can be understood as why are we thinking about this in the first place, and why is this work important to the business. The "what" is the problem's parameters -- what issue are you trying to solve with this design, and what are you explicitly not doing. It's also important to think deeply about who should be involved in the process and who should be informed of the changes. Often the most difficult part of building systems at scale is aligning your stakeholders, and setting the scene up front in a design document is a great way to bring people along in your process. Given that we have over 80 engineering teams working on a wide variety of services, a large change such as replacing our web framework of choice naturally affects a wide number of people. The team responsible for this conducts a series of design reviews to outline their thoughts and how this will affect the wider business. This gives each of the teams involved a place to contribute to and challenge the proposal while highlighting any assumptions that might not be correct. The design review process usually involves a single au ## Setting your engineers up for success: how Skyscanner created greater clarity in our competencies... DevFeed: [Setting your engineers up for success: how Skyscanner created greater clarity in our competencies...]() Original publisher: [Read original article]() Author: Skyscanner Engineering Published: 2022-09-22T12:03:23Z Content type: opinion Language: en Sources: [Stories by Skyscanner Engineering on Medium]() Topics: [Framework]() Tags: [career-progression](), [culture](), [delivery](), [engineering](), [framework](), [performance](), [review](), [scope](), [skills](), [training]() ### AI overview Skyscanner describes how it clarified its engineering competency framework and performance expectations to support fairer feedback, clearer role expectations, and career progression. The company simplified the framework and created dedicated training after identifying gaps in how managers and engineers understood expectations. ### Source excerpt Setting your engineers up for success: how Skyscanner created greater clarity in our competencies and pathways to progression By Emanuel Müller Ramos, Skyscanner Engineering Director For many companies, this time of year is often appraisal or performance review season. Feedback is really important as we each seek to learn, progress and improve generally. However, making sure everyone is rated fairly and consistently can often be tricky if companies don't have robust and clear frameworks in place. This is something we've worked hard to ensure we address here at Skyscanner, and today we'd like to share our journey of making competency frameworks, and performance expectations, really clear within our Engineering org. Supporting our engineers' growth is one of the most important responsibilities of our Engineering Managers. Part of this includes helping engineers understand the expectations of their role and level, while also having clarity as to what the next stage of someone's career might look like. To do so, Skyscanner has a competency framework outlining skills and behaviours for each level, from entry level roles all the way to CEO. However, while the competency framework was regularly shared and discussed, a few years ago we noticed that we'd occasionally find gaps in understanding. For instance: Some Engineering Managers having a gut feel that a engineer had a gap in their performance, but couldn't relate that to the competency framework expectations Some Engineering Managers feeling uncomfortable to deliver feedback because they were not sure if they were being over-demanding or if their ask was within the expectations of that level Some Engineers feeling frustrated because they were not fully sure how a gap highlighted by their manager connected to the expectations in the competency framework While cases like this were isolated, leaving it unchecked could have consequences on how we set our engineers up for success in their current role and in their career pro ## My Career Pivot: From IT recruiter to information security DevFeed: [My Career Pivot: From IT recruiter to information security]() Original publisher: [Read original article]() Author: Skyscanner Engineering Published: 2022-06-24T08:08:19Z Content type: article Language: en Sources: [Stories by Skyscanner Engineering on Medium]() Topics: [Security](), [Cybersecurity]() Tags: [career](), [engineering](), [female-engineers](), [information-security](), [pci-dss](), [security](), [security-engineering](), [women-in-tech]() ### AI overview This profile follows Maria Sepulveda's career transition from customer service and IT recruitment into information security. As a Senior Security Engineer at Skyscanner, she discusses her role, career development, and responsibility for leading the recertification of the company's PCI DSS compliance. ### Source excerpt Senior Security Engineer Maria Sepulveda As we celebrate International Women in Engineering Day this week, we're profiling female-identifying engineers across our business. Maria Sepulveda is a Senior Security Engineer at Skyscanner. An expert within information security, Maria led the recertification of Skyscanner's PCI DSS (Payment Card Industry data Security Standard) compliance. Maria took an unconventional path to information security, starting her career in customer service and IT recruitment. Here, she discusses her journey, imposter syndrome and what her role looks like today. Maria, as a Senior Security Engineer, what does your role involve? Well, I only recently joined Skyscanner so a typical day for me today might look different to a typical day in a couple of months time! Having said that, I have already been given responsibility to lead the recertification of our PCI-DSS compliance. It's great that I can be trusted so early on in my Skyscanner journey. My day typically starts with following up on tasks that are due in the coming week. During the day I meet with people and various teams to understand what they do. I'll also attend internal events, often to better understand the Skyscanner culture and the way things work here -- as well as to make connections. Focus Time in the afternoon allows me to re-read my notes and absorb information I obtained during the day. The day might end with a recap of the day with my team, allowing me to ask questions I haven't already asked or just generally talk about how the day went. What was your career journey to this point? I took an unconventional path into information security. Originally from Australia, I worked in customer service roles and IT recruitment. I arrived in London and found a job working at an in-house recruitment team for an online betting company. I knew that I wanted to move into a more tech-focussed role but still interfacing with the business. My colleague who was recruiting for the security team ## International Women in Engineering Day: reflections from our VP of Engineering, Myra Fulton DevFeed: [International Women in Engineering Day: reflections from our VP of Engineering, Myra Fulton]() Original publisher: [Read original article]() Author: Skyscanner Engineering Published: 2022-06-23T08:08:17Z Content type: article Language: en Sources: [Stories by Skyscanner Engineering on Medium]() Topics: [Software Engineering](), [Development](), [Testing](), [bug](), [Support]() Tags: [bug](), [career](), [documentation](), [engineering](), [engineering-leadership](), [problems](), [software](), [software-development](), [testing](), [vp-of-engineering](), [women-in-tech]() ### AI overview An interview with Skyscanner VP of Engineering Myra Fulton about her path from hospitality studies to software engineering leadership. She discusses lessons from support and mortgage development roles, including the importance of documentation, code quality, testing, and the real-world impact of software defects. ### Source excerpt Skyscanner VP of Engineering, Myra Fulton She is Skyscanner's most senior female engineer, but Myra Fulton's career as she knows it almost didn't happen -- a last-minute decision to change her university course from hospitality to engineering set her on a completely different path to the one she'd intended. This International Women In Engineering Day, we sat down with Myra to hear her about her journey to the top. Myra, what lead you to engineering originally -- was it always the plan? Engineering was very much not the plan -- I wanted to get into hospitality, and had dreams of running a hotel group. But fate -- in the form of an amazing teacher called Mr Haggerty -- intervened. He convinced me to take up computer science and basically changed the course of my career. He then did the same for a fellow engineer here at Skyscanner, Mhairi McClair several years later! So thank you, Mr Haggerty. The way Mr Haggerty taught computer science brought the subject to life -- I loved how you could solve problems in really interesting ways, and doing that with technology was exciting. It suited my analytical brain, so I decided to switch my uni course from Hospitality Management to Computer Studies. What happened next -- what was your journey to Skyscanner? I graduated with a first class honours spent a year's placement with IBM. After graduating, I got on the grad programme with a bank and spent nine years there. My career started in a number of first and second line support focused roles where I learned the importance of good handover documentation and run-books. I then got the privilege to lead the mortgage development team where I started to learn the other side of software development. It was during my time there that said bank had announced they'd undercharged people for mortgages due to a bug in services. While I wasn't involved in that bug, it really taught me the fragility of software and the importance of the quality of code, of testing and of the impact that can be made on ## My Career Pivot: From Retail to Engineering DevFeed: [My Career Pivot: From Retail to Engineering]() Original publisher: [Read original article]() Author: Skyscanner Engineering Published: 2022-06-22T09:59:02Z Content type: opinion Language: en Sources: [Stories by Skyscanner Engineering on Medium]() Topics: [Software Engineering](), [Development](), [Front end](), [Bootcamp](), [front-end-development]() Tags: [career](), [career-change](), [course](), [developer](), [front-end-development](), [software-engineer](), [software-engineering](), [women-in-tech]() ### AI overview Louise Reid describes moving from retail and system support into software engineering. She discusses online courses, a 16-week CodeClan bootcamp, her time as an instructor, and her eventual focus on front-end development before joining Skyscanner. ### Source excerpt Louise Reid, Software Engineer As we celebrate International Women in Engineering Day this week, we're profiling female-identifying engineers across Skyscanner's business. Here, Louise Reid tells us how she took the leap from retail to software engineering, what her day to day looks like, her advice for anyone looking to career change, and how the perception of engineering being male-dominated is changing. Louise, you didn't set out to be an engineer -- what was the path that took you from retail to where you are now? I didn't: I have a honours degree in Business and Management. Honestly, going through school, the concept of working as a software developer was so far off my radar. During my degree I worked in hospitality and really enjoyed it, so for a while saw myself working in hospitality management in some shape or form. After uni I travelled in Australia for a bit and then went back to my role in retail with a large well-known shoe retailer, before moving to head office there and working in system-support for the stores. At 29 I found myself in a job that didn't excite me and wasn't really going anywhere. I was really good at my job, but there wasn't a huge amount much transferable knowledge I could take from it into other roles, as a lot of it was in house-built systems. I was also at the level that any progression was reliant on someone above me leaving or the company expanding in some way. It wasn't until I started working with developers there that I started to think of software engineering as a path I could take too. I dipped my toe in the water a little, doing some free online courses with Code Academy, which I really enjoyed. I was then pointed in the direction of CodeClan by my line manager and introduced to their 16 week software development bootcamp. After completing the course I still had a sense of "I don't know what I want to do" and whilst I got offered a few development roles, none of them really excited me. I ended up staying at CodeClan as a cla