One of the most reliable ways a psychologist separates a serious candidate from a superficial one is to ask what actually happens after acceptance. Not because the details are secret (they are on the academy's website), but because a candidate who never looked them up has told the psychologist something important about their motivation. You should be able to describe your training route and the career ladder behind it in your own words.
The training route
A typical integrated programme in Europe is planned at around two years and famously tends to run longer. It opens with the theory: thirteen ATPL subjects — from meteorology and air law to performance, navigation and human factors — each closed with an exam to the European standard, where 75% is the legal pass mark and ambitious students aim far higher. Then the flying builds in stages; the exact sequence varies by academy, but typically it runs: a visual-flying (VFR) phase on a single-engine trainer, with the first solo as its early milestone; a night rating; the commercial licence (CPL) finished on a more complex aircraft; upset-prevention-and-recovery training in an aerobatic type; the multi-engine and instrument ratings, flown partly in simulators and partly on a twin, taking you into airways flying; and finally the multi-crew cooperation course on a jet simulator, where you stop flying alone and start working as a crew. Pass all of it and you hold a frozen ATPL; the airline then adds a type rating for its own aircraft in a full-flight simulator. Modular routes cover the same ground in separate blocks. And a growing number of airlines recruit instead through MPL programmes, a Multi-Crew Pilot Licence trained from early on in a multi-crew, airline-specific environment, with the licence tied to that airline's operation. If your target airline runs one, be able to explain that difference.
Learn the specifics of your programme — the aircraft types, the bases, whether theory is front-loaded or interleaved with flying — from the academy's own material, and be ready to say why that structure suits you. Getting these details right, unprompted, is quiet proof that your interest predates the interview.
What 'frozen ATPL' means
You graduate with an Airline Transport Pilot Licence that is 'frozen': all the theory is done, but the licence only fully activates (unfreezes) once you have logged the required flying experience, typically 1,500 hours. In the meantime you work as a first or second officer under a captain. Being able to explain this term correctly is a small thing that signals you have read past the brochures.
The career ladder
How you advance is the part of the answer you most need to tailor, because airlines run on two quite different promotion models. Describing the wrong one in your interview is exactly the superficial knowledge this question is designed to expose.
Seniority-list airlines — most flag carriers and legacy airlines: on joining you receive a seniority number based on your date of entry, and when upgrade positions open, pilots bid for them, with the list deciding who gets the training slot. Flying hours and performance reviews do not move you up the list; time in the company does.
Experience-and-merit airlines — most low-cost carriers and many carriers in the Gulf and Asia: a command upgrade comes when you meet the airline's experience thresholds and pass a command assessment, so the pace is set by your hours, your standing in training and how fast the airline is growing.
The starting rung varies just as much. At some long-haul flag carriers cadets begin as second officer or cruise-relief pilot on intercontinental routes, moving into a first-officer seat later; at most short-haul and low-cost carriers you go straight onto the line as first officer. From there, a typical flag-carrier ladder alternates between fleets: first officer on short-haul, then long-haul, captain on short-haul, and finally captain on intercontinental routes. A low-cost ladder is simply first officer to captain, sometimes via a senior-first-officer grade, and often faster. Some airline groups also offer a route through a regional subsidiary, where an earlier command there counts toward a later mainline one.
How long each rung takes depends on fleet growth, retirements and the economy: in boom years a low-cost command can come within a handful of years, while a long-haul command at a flag carrier can take two decades. So find out which model your target airline uses and roughly how long its queue currently is. Quoting that realistic, airline-specific timeline impresses; expecting four stripes by thirty does not.
How to prepare
Build a one-page mental map for the airline you are applying to: the training phases in order, the aircraft and role you would start on, and the typical progression from there. The goal is not to recite it (a memorised monologue is its own red flag) but to answer follow-up questions naturally, the way you would about any subject you genuinely know. If the airline has a cadet academy, its own open-day material is the single best source, because it is the version of the story your interviewer knows.