AIRCRAFT RELIABILITY – You Can Only Manage What You Can Measure

That phrase and several variations of it have been attributed to management and productivity masters such as Demming, Druker, and others concur that you can only manage what you can measure. Business leaders know this almost instinctually. So how can the logic effectively be applied effectively to reliability of the company aircraft?

Imagine the CFO who only sees two numbers: total expenses and total income. How could they adequately manage the finances of the company adequately with just that?  But, if the CFO were to get with a copy of every dollar spent and received, they would be inundated with data.  In an ideal scenario, various levels of management need various levels of information.  For example, the store cashier needs to balance out the their cash register till at the end of the shift. The store manager needs to know the cost of overtime and sales by department, and the CFO needs a sufficiently high enough level of data to know the company’s performance year-to-year, income seasonality, advertising budgets, etc.

Transferring a similar model to aviation, the pilot needs to know how much fuel is required for the trip, the aviation manager needs to know the cost of fuel from various sources and total fuel used, and the manager of the company’s aviation function needs to have measurements on how well the aviation function is doing.

Two major aircraft productivity measurements that are commonly used for flight departments (among others) are trips & and hours flown, and passengers carried. Others may be the number of trips requested and the number of trips that could not be met. These could show is how well, or how reliable the service is delivered.

Dispatch Reliability and Availability and Reliability

Aircraft availability and dispatch reliability and availability are two vital signs of any aviation operation. Availability refers to whether the aircraft is available for a flight, whether scheduled or not. An aircraft in for maintenance cannot be flown, and thus is not available. Does your aircraft spend too much time in the maintenance shop and too little time available for flight?

Aircraft reliability is where the rubber meets to road (or runway as it were). At its most basic, aircraft dispatch reliability accounts for whether the aircraft took-off on time and if not, why? If the dispatch performance and/or reliability of the aircraft is poor, then so is the level of service. If your car spent a lot of time in the dealer’s service department or broke down once a month and needed to be towed, you would want to know why.

The airlines recognize the importance of these metrics and spend considerable a lot of resources defining and tracking this sort of information. To the airlines, a standard reliability window is a departure from the gate within 15 minutes of schedule. They exclude non-aircraft issues such as air traffic delays, bad weather, connection delays (due to waiting on transferring passengers), etc.). Scheduled airlines end up with an aircraft dispatch reliability percentage that is tracked and updated continuously. The goal for most airlines is a dispatch reliability rate in excess of 99%. Most data suggest that the large regional and major airlines achieve between 96-98%, with the most reliable carriers achieving 99-99.5% dispatch reliability.

Both Boeing and Airbus claim high reliability rates. Recent press claims that the Airbus A330 exceeds 99% dispatch reliability and the latest Boeing 737 models are at 99.4%. Bombardier gives out awards to regional airlines that exceed 99% dispatch reliability with their Dash 8 turboprop and CRJ regional jets.

On time departures means make happy customers, and happy customers return to spend more money. The airlines are very serious about this metric and review this it on a daily basis. A cancelled airline flight means increased costs and the possibility of lost revenue if passengers fly a different airline in the future.

Business Aviation Tracking Issues

From my experience, operators of business aircraft do not track reliability or availability or reliability with the same focus. Perhaps that is because reliability and availability and reliability have never been a big issue in Corporate Aviation. Or, for a single aircraft that files 200 trips per year, the number is easily counted?

The cost to your business of a delayed or cancelled private flight can be significant. The business aircraft is selected favored for its ability to minimize travel time. Sitting around waiting for the airplane to be fixed is not an efficient use of your time or the capital invested in your flight department. For the business aircraft to be able to meets is meet its productivity promise, it has to be on-time, all of the time.

Anecdotally, it looks like Business Aviation appears to focus on dispatch reliability more so than aircraft availability. The manufacturers release limited data. Gulfstream reported that the G450/550 fleet routinely exceeds 99% reliability dispatch reliability (achieving 99.87% in 2009). Rates for older and out-of-production aircraft are generally not to be found.

Aircraft availability figures are much lower.  It is not unusual for availability numbers to be about 85 percent, and some fleet operators deal with aircraft availability in the vicinity of 80 percent due to issues associated with unscheduled maintenance.

Many business aircraft operators do not track availability, and those that do track such data may not all use the same definition in calculating such performance. The National Business Aviation Association is working to fix both the problem of tracking data at all among operators and the uniformity of data tracked.

At present it has a tool called FERMS, the Forum for Enhanced Reliability and Maintainability Standards. FERMS is a web-based tool providing business aircraft manufacturers and operators with real-time information about business aircraft maintenance and performance.

NBAA has defined the metric for measuring the reliability and operational availability and reliability of business aircraft. This secure collection tool is available for NBAA members and select industry participants such as the aircraft manufacturers.

The factual data will ultimately serve to validate reliability and maintenance programs, bringing about timely response to maintenance and operational issues. The key to success is to record this information consistently and accurately. NBAA’s FERMS seeks to achieve this. If your aviation operation is not yet a part of this effort, I encourage you to consider it. Regardless, there is not reason not to track availability and reliability metrics. 

The payoff is you will have gain hard information with which to analyze the benefits of how well the company aircraft is maintained, and what the impact of maintainability and reliability programs have on the ability of your company’s flight department to satisfy the corporation’s transportation needs.

When working with operators, I find that those that track this type of data also have the highest reliability rates. This type of data collection seems to correlate with those aviation operations that are efficiently run and offer the high levels of service that Business Aviation promises.

AIRCRAFT RELIABILITY – You Can Only Manage What You Can Measure

2 thoughts on “AIRCRAFT RELIABILITY – You Can Only Manage What You Can Measure

  1. Someone judgment of a company in the field of aviation is going to always be different. People who have the appropriate assessment are usually a person who resides in the company and have the ability to analyze.

  2. […] Aircraft availability and dispatch reliability and availability are two vital signs of any aviation operation. Availability refers to whether the aircraft is available for a flight, whether scheduled or not. An aircraft in for maintenance cannot be flown, and thus is not available. …. At its most basic, aircraft dispatch reliability accounts for whether the aircraft took-off on time and if not, why? If the dispatch performance and/or reliability of the aircraft is poor, then so is the level of service. ……. […]

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