Mario Pierobon holds a Master’s Degree in Air Transportation Management from City University... Read More
This concept has achieved some critical mass and is supported by several software developers and consultancies (so much so that recommended practices such as single engine taxi have become almost standard procedure among the large international airlines).
While fuel management as a concept was developed specifically for the airlines, it also applies to Business Aviation. However, due to the importance of time-savings in business aircraft operations, aircraft performance in relation to mission of a business jet is so important that fuel can often become a secondary consideration in management and operational decision-making.
The Cost Index Equation
Marcel Martineau - a former Airbus A330/A340 captain and current owner of Total Fuel Management – refers to the ‘Cost Index’ as a notion for decision-making. This mathematical formula is used as a flexible tool to control fuel burn and trip time in order to obtain the best overall economics.
The Cost Index, when inserted into the flight management computer of an aircraft adequately-equipped aircraft, will optimize the speed, balancing the cost of fuel with the cost of time. As an example, a metric Cost Index of 20 would means that the aircraft will consume up to 20kg (40 lbs) of fuel to reduce the flight time by one minute:
Cost Index = Cost of time ($/Min) / Cost of fuel ($/kg).
The idea is to determine the cost for that minute. The ‘cost of time’ normally factors crew cost, time-related maintenance cost and delay cost - thus you can determine what that minute is worth and how much fuel must be burnt to save that minute.
In the case of business aircraft operations, the Cost Index is such that the cost of fuel is only a fraction of the overall cost. Since the cost of fuel is relatively small compared to other costs of operating a business jet, operators often tend to minimize the importance of the fuel management and cost. Nevertheless, the Business Aviation industry has seen a rise in relevance of the Cost Index model from business aircraft operators managing larger fleets.
In a changing industry fuel management becomes a prime candidate for consideration, especially when you consider that the relative fuel consumption for business aircraft is higher compared to commercial aircraft. [The commercial aircraft will consume approximately 4 litres (8.3 lbs) per passenger, per 100km (54nm) whereas a business aircraft carrying five passengers will consume 10 times that amount.]
“Fuel tankering is actually more manageable in business aircraft operations,” notes Martineau. “Business jets typically have quite long range capabilities and the legs flown are often relatively short. Considering that business aircraft tend to spend more per gallon of fuel compared to the scheduled international airlines, tankering fuel purchased at FBOs where better deals can be obtained is certainly a very sensible move.
“Optimizing the speed to the mission is also quite important. Business aircraft are often ferried to a departure destination. In a ferry flight there is no need to fly at high-speed where long-range cruise speed can suffice, giving better fuel efficiency,” adds Martineau.
The availability of data means an opportunity for more informed decisions regarding fuel management. The provision of fuel efficiency information to flight crews as part of their briefing process (such as fuel efficiency information on the upcoming leg during the pre-flight briefing) can provide a valuable contribution.
“Business aircraft can minimize fuel consumption with good weather information and accurate flight planning,” offers Martineau. “The choice of a close alternate airport will reduce the landing fuel.”
Important fuel consumption data can be derived from Flight Data Monitoring (FDM) systems and Aircraft Performance Monitoring (APM) - although Martineau believes that the justification of investing in such programs (especially for aircraft weighing less than 60,000 lbs MTOW that are not required to perform FDM) is a question of economics with many business aircraft flying a less hours annually than the scheduled airlines and it’s unlikely that the cost of a FOQA program can be justified, except in the case of an operator managing a large number of aircraft.
Savings & Safety
A wide range of flight operations procedures reduce fuel consumption, are safety sensitive and need appropriate control actions, including:
• Engine-out taxi-out
• Reduced takeoff flaps
• Reduced acceleration altitudes on takeoff
• Continuous climb operation
• Constant descent operation
• Low noise, low drag approach
• Reduced flaps landing
• Idle reverse on landing, and
• Engine out–taxi in.
“All of these procedures are applicable to business aircraft,” notes Martineau. “They need to be adjusted for the circumstances. For example, business aircraft tend to use smaller airports where runways can be relatively short. So use of reduced flap landings or idle reversers on landing might not apply.
“It is all a question of airmanship,” he concluded. “Note that efficient pilots are normally safer pilots since efficient flying requires increased attention to detail and higher concentration. Efficient pilots will be focus on every detail which will result in increased situational awareness.”