Reliability Engineering is the engineering discipline concerned with understanding how aircraft systems, components and maintenance processes perform over time.
In airline Maintenance & Engineering, Reliability Engineers analyse operational and maintenance data to identify recurring defects, component-performance issues, technical delays and other changes in fleet performance that may require further investigation.
The objective is to provide Engineering with a structured, evidence-based view of where reliability is changing and where technical attention may be required.
What does a Reliability Engineer do?
A Reliability Engineer typically works with information from the M&E system and other operational sources, including:
aircraft utilisation;
pilot, cabin and maintenance defects;
technical delays and cancellations;
repetitive defects;
deferred defects;
component removals;
MTBUR and MTBF indicators;
maintenance-programme findings;
aircraft and ATA chapter performance.
These data are analysed over time so that changes in technical performance can be identified and investigated.
For example, an increase in defects within a particular ATA chapter may lead Engineering to review the affected aircraft, defect descriptions, corrective actions and maintenance history before deciding whether further action is necessary.
Reliability Engineering and the Reliability Programme
Reliability Engineering is closely connected with the operator's aircraft reliability programme.
Where a reliability programme is required or established within the approved Aircraft Maintenance Programme, it defines how aircraft and system performance will be monitored, which indicators will be used and how adverse trends or alert-level exceedances will be reviewed.
The purpose is to help determine whether the maintenance programme continues to be effective and whether particular technical areas require additional investigation.
Learn more in our glossary guide to the Aircraft Reliability Program.
Reliability Reporting
Many operators use periodic reliability reports to bring together the indicators defined within their reliability programme.
The exact content and reporting frequency depend on the operator, fleet and approved programme. A report may include measures such as:
technical dispatch reliability;
defect rates by ATA chapter;
repetitive defects;
delays and cancellations;
unscheduled component-removal rates;
MTBUR or MTBF;
deferred defects;
maintenance-programme effectiveness.
The report provides a structured view of fleet performance, but the engineering value comes from understanding what is driving the changes behind those indicators.
Read more about why monthly reliability reporting can still take significant preparation.
From Reliability Reporting to Reliability Analysis
Preparing the report is only one part of Reliability Engineering.
Once the indicators are available, engineers need to investigate the aircraft, systems, defects and components behind the numbers.
For example, a deteriorating defect rate becomes more useful when Engineering can identify which aircraft are driving the trend, which defect descriptions recur and what maintenance actions were performed.
This is the progression EXSYN describes as Reliability Intelligence: moving from reporting what happened toward identifying the patterns and operational context that help engineers understand where further investigation is required.
EXSYN's Reliability Intelligence solution supports this process by calculating consistent indicators from existing M&E data and allowing engineers to investigate reliability performance by aircraft, ATA chapter, defect and component.
Reliability Engineering and Data Quality
Reliability analysis depends on the quality of the operational information underneath it.
Missing aircraft utilisation, inconsistent defect classification, duplicate records or incomplete component history can change the resulting reliability indicator and make trends harder to interpret.
This is why data validation forms an important part of the reliability process. EXSYN's current Reliability Intelligence solution combines Reliability Reporting and Reliability Analysis with M&E consistency checks so that engineers can work from more consistent operational inputs.
Reliability Engineering and Predictive Analysis
Reliable historical analysis can also provide a foundation for earlier risk detection.
Once Engineering understands normal fleet performance and recurring technical patterns, historical defects, component behaviour and maintenance events can be used to investigate whether similar conditions are developing again.
Predictive tools can support that process, but they do not replace Reliability Engineering. Engineers still need to interpret the technical context and determine whether a finding requires monitoring, maintenance action or further investigation.
For a broader discussion, see our glossary definitions of Predictive Analytics and Predictive Maintenance.
