Aircraft maintenance — A vast field with tons of KPIs
Aircraft maintenance, undoubtedly, is a vast area. Base maintenance, line maintenance, component management, engine overhaul — the list is almost endless. Moreover, each sub-areas maintains and monitors specific sets of KPIs tailored to their needs, goals, and regulations. And that totally makes sense since performing a ramp check is entirely different from an engine overhaul.
Aircraft maintenance KPIs and airline operations
This article’s idea isn’t to dig into each sub-category but to introduce five aircraft maintenance KPIs that play a vital role in airline operations. These KPIs directly impact an airline’s day-to-day performance and, even more importantly, can lead to massive disruptions. Therefore, it isn’t —solely— up to the maintenance department to monitor the KPIs closely.
On the contrary, it essential to include those indicators into operations real-time dashboards — besides other metrics, such as on-time performance or regularity. In that context, a perfect real-time dashboard combines information from different areas, curates them, and visualizes it so users can rapidly understand and assess the current situation.
5 Aircraft maintenance KPIs airlines have to monitor
The area of aircraft maintenance, in fact, creates an enormous amount of data and information. And if you ask colleagues from aircraft maintenance, they tell you that all of it is important. However, we carefully selected five aircraft maintenance KPIs, which we consider critical. So let’s get into it! Here’s an overview of the KPI in case you want to jump to a certain KPI directly:
Aircraft On Ground (AOG)
I’m pretty sure “Aircraft On Ground (AOG)” is among the TOP 10 terms airlines, and especially airline operations, hate most. Let’s have a quick definition first. The term “Aircraft On Ground” indicates an aircraft’s ad-hoc inability for further usage due to technical issues. And there are thousands of reasons or situations that can lead to AOGs. I’ve seen AOGs due to lightning or bird strikes and AOGs due to broken toilets or doors. However, all AOGs have one thing in common: They require a maintenance event to get the aircraft back into operations.
Why’s this KPI essential? An AOG —always— represents one of the most critical disruptions to the flight schedule. Depending on your aircraft reserves, an AOG can directly lead to flight cancellations. Accordingly, it is crucial to have a close eye on the number of AOG during day-to-day operations. We usually visualize this as a bold figure on the aWall, solely showing the amount of aircraft that are flagged as AOG.
Directly after AOG, unplanned events represent another critical aspect. Again, let’s start with a short definition first. Usually, maintenance events follow precise planning and scheduling for every aircraft. If everything works as planned, thresholds (number of cycles, block hours, etc.) define the maintenance event’s execution. But we all know there’s a plan, and there’s reality. In that context, unplanned events represent aircraft maintenance tasks (on the day of operations) that haven’t been scheduled. And again, tons of reasons can lead to an unplanned event. The above mentioned AOG is just one example of events that lead to unplanned aircraft maintenance.
However, the problem with unplanned events is similar to AOG and very obvious: Every unplanned event unexpectedly disrupts the flight schedule. Therefore, our clear advice is to monitor several aspects of unplanned events:
- First and most importantly, the number of unplanned events on the day-of-operations
- Additionally, since the duration of unplanned events can vary massively, the total duration of today’s unplanned events (in minutes or hours) is vital.
- In case an airline operated different aircraft types, it is worth to cluster the information accordingly.
- Finally, it is extremely valuable to include the location of unplanned events (outstation or base)
Planned Checks + Status
Let’s move on to a —at least at first sight— more controllable area. First of all, planned checks are obviously the opposite of unplanned checks. Accordingly, we are talking about aircraft maintenance events that have been scheduled. Therefore, —and if executed correctly— planned checks shouldn’t impact your flight schedule at all.
However, two there are two aspects why this aircraft maintenance is essential:
- To gain a holistic situational awareness of your flight operations, it is vital to have a clear overview of aircraft that are flying and under maintenance.
- More importantly, as soon as a check takes longer than expected and the aircraft’s release to service is delayed, it can have a direct impact on your flight schedule.
Therefore, we suggest visualizing the topic of unplanned checks in two variations. On the one hand, there’s the plain KPI, including today’s total number of unplanned and already performed checks. On top of that, we strongly advise having a real-time list that contains more detailed information, such as:
- What kind of check?
- Which aircraft is affected?
- At which airport is the check performed?
- Schedule start and end date/time
- Actual start and end/time
As mentioned previously, especially the last attribute (delay) is crucial for operations.
Event punctuality represents a rarely used yet crucial aircraft maintenance KPI. So you might ask if the KPI is that essential when only a few airlines monitor it. Absolutely yes. Almost every airline I know would love to monitor this KPI. However, many airlines face a data availability problem.
But, again, let’s have a look at the definition first. Quickly explained, the event punctuality is the on-time performance of an aircraft maintenance event. Since every planned aircraft maintenance event has a scheduled finish time, you can precisely track punctuality. Accordingly, the event punctuality is calculated as the share of events executed as planned in relation to all completed events.
Personally, I would rate this aircraft maintenance KPI as one of the TOP-3 (besides AOG and Standby Aircraft). The KPI provides an unmatchable comprehensive overview of how maintenance performs on a specific day. And of course, it makes sense to cluster that aircraft maintenance KPI according to the different dimensions again, such as:
- Maintenance stations
- Aircraft type
- Event type
Standby Aircraft / Reserves
So here’s another killer KPI. Standy aircraft represents one of the essential aircraft maintenance KPIs. Although airlines (at least pre-COVID) continuously reduced the number of standby aircraft due to the immense aircraft demand, it is just vital to monitor this KPI.
The KPI itself is relatively simple: It calculates and shows the number of available standby aircraft. Of course, depending on an airline’s fleet structure, clustering the KPI according to aircraft types is reasonable.
So why’s this aircraft maintenance KPI essential? Because it’s your back-up. AOGs, unplanned events, bad punctuality — with standby aircraft cover all of it and reduce the impact. However, once no standby aircraft is available, things get really hairy. That’s the time when you have to cancel flights or deal with substantial disruptive impacts.