The Hidden Bottleneck in ATC Recovery: Instructors and OJTIs
The industry has become comfortable saying that the controller shortage is about recruitment. That is only partly true. In practice, many organisations are discovering that the real constraint sits further down the line: not in attracting candidates, but in finding enough experienced instructors, simulators and OJTIs to convert trainees into validated controllers at the speed the network now needs.
Why instructor capacity now matters more than applicant numbers
A trainee does not become useful capacity when they accept an offer, or even when they pass initial training. They become useful capacity when an operational unit can safely absorb them, supervise them and validate them. That is why instructor capacity now deserves the same executive attention as recruitment and retirement.
CANSO’s 2025 workforce analysis is unusually clear on this point. It says the training stream becomes critical once recruitment begins, and that while initial classroom instruction can be expanded, the real bottleneck occurs in advanced training, where simulator access, expert tuition and operational OJT are the notable constraints. It then goes further and says that addressing instructor shortages is essential to delivering high-quality training for future controllers.
Where the pipeline actually stalls
This matters because many workforce dashboards are still built around the wrong stage of the journey. They show applications, start dates and classroom progress, but tell leaders too little about movement through simulator phases, local endorsement training and final validation. NATS’ public material gives a more realistic picture: 12–15 months of initial training is only the front end, after which trainees move into supervised live operations until they validate, and the whole journey can take up to three years.
The same pattern appears elsewhere. DFS Deutsche Flugsicherung reported that 364 people, including OJT controllers, were in multi-year ATCO training at the end of 2024. NAV CANADA said in 2025 that staffing remained its top priority and that it was increasing training capacity, including through a partnership designed to expand qualification output. Large pipelines are clearly being built. The harder question is how quickly advanced training can safely absorb them.
The vicious circle of understaffing
The instructor problem is especially difficult because it is self-reinforcing. IFATCA’s 2025 paper on attracting new controllers says training capacity can be limited by simulator availability, OJT position limitations or instructor shortages in either initial training or OJT. In an understaffed unit, experienced controllers are often needed both on live sectors and in the training role, which means current operational pressure can directly slow future staffing recovery.
That creates the classic vicious circle. Shortage reduces spare experienced capacity. Reduced spare capacity limits teaching and validation time. Slower validation prolongs the shortage. Organisations then work harder on recruitment while the real bottleneck remains largely unchanged. That is precisely why instructor capacity should be treated as a strategic production constraint, not as a background support function.
What a serious instructor strategy looks like
A credible response starts with recognising that instructor capacity is not just a headcount. It includes protected time, quality of coaching, consistency of standards, availability of simulators, local endorsement complexity and the workload placed on the instructors themselves. CANSO has already suggested that best-practice guidance on instructor selection and training would add value, which is another way of saying that instructor capability needs to be designed, not assumed.
In practice, that means selecting the right people into instructor roles, training them properly, monitoring whether they are being pulled back into live operations too often, and building succession so that a small number of senior experts are not carrying the whole system. It also means protecting OJTI and instructor time during seasonal peaks, because this is exactly when the temptation to sacrifice training for short-term rostering relief is greatest.
What can be externalised and what cannot
The answer is not always to do more internally. IFATCA’s 2026 working paper on outsourcing initial training recognises that ANSPs trying to increase licensed controller numbers may need to expand capacity through external provision of basic and rating training. NATS likewise reports that it has partnered with an external training provider to increase capacity and improve training effectiveness.
But the industry should also be honest about the limits of outsourcing. Initial theory, simulator exposure and some rating work can be standardised and purchased. Unit-specific supervision, judgement-building, local endorsement and credibility in live traffic cannot simply be outsourced away. The decision is therefore not whether to use outside support, but where to place the boundary so that internal experts are used where they add the most value.
What boards should ask now
Senior leaders do not need to become training specialists, but they do need better questions. How many instructors and OJTIs does the operation actually have, by unit and endorsement? How much time is protected for training? How many trainees are stalled at advanced stages? How many experienced staff will retire or move role before the current trainee cohorts validate? Those questions reveal more than a simple vacancy number ever will.
The harder but more useful conclusion is that many ATC recovery plans are now instructor recovery plans in disguise. Recruitment remains necessary, but it will not restore resilience fast enough unless the sector addresses the people who teach, supervise and validate the next generation. That is the hidden bottleneck — and, for many organisations, the place where the most practical gains now sit.
