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Reliability and Availability

by David Wyndham 1. July 2007 00:00
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The news is full of how well all the aircraft manufacturers are going in new aircraft sales. Also doing quite well are sales of used aircraft. Still the majority of us are not buying right now. For many, your current aircraft is doing just fine, thank you. But is it? Here are two things to track to know how well your aircraft is doing.

Dispatch Reliability is defined as the percentage of departures that leave within a specified period of a scheduled departure time. Is the aircraft ready to fly? Ninety-eight percent dispatch reliability is a standard that many aircraft operators achieve. In order to keep an aircraft reliable, it requires the aircraft to be kept in excellent mechanical condition.

If your aircraft does not make its scheduled departure, what was the reason? Weather, ATC delay, crew delay, maintenance delay?

Weather and ATC are beyond your control. But the other two should be at or very near to zero. If you are frequently running out of crew duty day, do you need to plan your trips better? Even if you are owner-flown, you need to schedule adequate rest. If your aircraft breaks frequently, do you need to replace the aircraft or find another maintenance vendor? Could it be that age has caught up to your aircraft? Even if dispatch reliability is excellent, you may still be loosing out due to availability.

Older aircraft cost more to maintain than newer aircraft. Even if dispatch reliability is high, keeping an older aircraft fit tends to not only require more money, but more time.

Aircraft Availability is defined as a percentage of days an aircraft is available for flight in an operating year. When your aircraft is in for maintenance, it is not available for flight. The more time your aircraft spends in or waiting for maintenance, the less time the aircraft is available to be scheduled for flights.

There are 365 days in a year. You should know the status of the aircraft for each day, regardless of whether it is scheduled for flight. Decreasing availability is typical of older aircraft and along with the increasing maintenance costs, can be a strong indicator of when to replace your aircraft.

If you are a low utilization operator who has flexibility in scheduling trips, then decreasing availability may not be as big an issue for you. You can rearrange travel, or take other means if air travel is an option, not a requirement. However, whether personal or business, not having an aircraft when you want it is an inconvenience. The more you fly the greater availability you need. High utilization operators tend to favor newer aircraft with less onerous maintenance requirements.

Tracking dispatch reliability and availability don't take a lot of time, and you can even build it up from (well kept) historical records. It can be an indicator of issues that may lead to an aircraft replacement.

How many of you track either or both of these? Let me know.


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