Why aircraft engine planning has outgrown simple “fly forwards” approaches

The global commercial aircraft fleet has grown substantially over the past decade, rising from around 21,600 aircraft in 2014 to more than 30,000 active aircraft by mid-2025. As fleets have expanded, the number of potential operational decisions has grown exponentially. Today, the modern powerplant manager faces a difficult balancing act. Airworthiness requirements must be met, engines need to be available when the operation needs them and budgets have to be controlled. At the same time, fleet plans change, maintenance schedules move, and unexpected engine removals occur.

For decades, spreadsheets have been the primary tool for navigating this complexity. While spreadsheets remain useful for many tasks, the scale and interconnected nature of modern engine management has begun to stretch their limits.

Engine assignments, shop visit timing, life-limited-part (LLP) consumption, spare engine deployment, lease-return conditions, fleet retirements and aircraft deliveries all influence one another. A decision made today can have operational and financial consequences that only become visible years later.

As engine fleets become more complex, powerplant teams are turning to Operational Research (OR) to evaluate connected decisions across the entire fleet rather than one engine at a time.

What is Operational Research?

Operational Research is a discipline focused on improving decision-making when multiple competing objectives exist. Within aviation, OR is already widely used in functions such as revenue management, aircraft assignment and crew rostering, helping organisations evaluate large numbers of options and identify stronger outcomes than manual planning approaches can typically achieve.

The same challenge exists within powerplant management. Managers want to minimise maintenance spend, maximise engine availability, extend LLP life and maintain operational flexibility. These objectives are connected, and decisions that improve one area can sometimes create unintended consequences elsewhere.

OR allows airlines to evaluate these trade-offs across an entire fleet. Rather than asking whether a plan is technically feasible, it helps identify which feasible option delivers the strongest operational and financial outcome over the lifecycle of the fleet.

For airlines looking to introduce this approach, the key is to apply operational research techniques to help powerplant teams optimise engine planning, improve lifecycle economics and strengthen long-term decision-making.

Why traditional planning approaches are reaching their limits

Powerplant management has become significantly more data-intensive over time. A fleet of 50 aircraft can generate billions of possible planning combinations across a five-year horizon. Maintenance timing, spare engine requirements, LLP utilisation, fleet transitions and operational constraints all interact with one another.

Human planners rely on engineering expertise, proven rules of thumb, and experience to navigate these challenges. And while those skills remain critical, even the most experienced team can only evaluate a limited number of future scenarios manually.

OR provides a way to assess far more possibilities than a spreadsheet-based approach can reasonably handle. Instead of focusing on one maintenance event or one engine at a time, it evaluates the fleet as an interconnected system and measures the economic implications of different decisions across the entire lifecycle. The result is greater visibility into future opportunities, risks, and trade-offs.

Three ways OR changes powerplant decision-making

While Operational Research draws on several different optimisation techniques, its practical value for powerplant teams generally falls into three areas:

Improving long-term planning decisions: Powerplant managers regularly face decisions about maintenance timing, engine inductions, module swaps and LLP usage. Each decision affects future options available to the fleet.

OR helps airlines evaluate these decisions within the wider fleet context, showing how actions taken today affect costs, availability and flexibility in future years.

This matters because available options naturally narrow over time. An intervention that creates value today may no longer be available six months later. By evaluating long-term implications earlier, airlines preserve more opportunities to influence outcomes.

Building resilience into changing plans: Many powerplant managers are understandably skeptical about long-term planning because airline operations are constantly changing. Aircraft schedules move, engine removals happen unexpectedly, fleet retirement assumptions evolve. Disruptions occur.

OR accommodates this uncertainty by allowing airlines to evaluate multiple future scenarios and update plans as new information becomes available. Planning becomes a continuous process rather than a one-off exercise. This gives managers a clearer understanding of the consequences of changing assumptions and decisions and helps keep long-term plans aligned with operational reality.

Identifying future shortages before they arrive

One of the most valuable outcomes of OR is earlier visibility of constraints. By modelling how engines and LLPs move through their lifecycle, airlines can identify future shortages years before they become operational problems.

This additional foresight creates time to evaluate alternatives, secure additional capacity or adjust plans. Leadership teams can make decisions before shortages become urgent rather than responding under pressure once they arrive.

For many airlines, this shift from reactive firefighting to proactive planning represents one of the biggest benefits of adopting OR-based approaches.

Supporting better decisions, not replacing engineering judgement

Operational Research does not replace the expertise and experience of powerplant teams. Its value comes from complementing that expertise.

Engineers and planners remain responsible for interpreting recommendations, managing exceptions and making final decisions. OR provides the ability to evaluate options, quantify trade-offs and understand long-term consequences more comprehensively than manual methods alone.

The approach can also strengthen conversations with executive stakeholders. When budget pressures emerge or business priorities shift, powerplant managers have evidence to demonstrate how different decisions affect both costs and fleet performance.

Importantly, hard requirements do not change. Airworthiness constraints and availability targets remain fixed. OR helps identify the most efficient route within those boundaries.

A new chapter for powerplant management

Many airline functions have already embraced data-driven optimisation to support complex decisions. Powerplant management now have the same opportunity.

Advances in computing power and the availability of more structured operational data have removed many of the barriers that once limited adoption. As a result, powerplant teams can move beyond maintaining workable plans and start evaluating what the best available plan looks like across the entire fleet.

For airlines managing increasingly complex engine fleets, the opportunity extends well beyond reducing maintenance costs. Operational Research offers greater foresight, improved planning resilience and stronger visibility into the long-term consequences of today’s decisions.