Pilots have a major influence on a fuel preservation program, as it is during flight execution that significant fuel savings can be achieved. In this article, we explore several fuel-saving actions to help you improve the fuel efficiency of your flights. These eco-flying techniques play a crucial role in reducing the environmental impact of air travel.
In this recap, you will find the main techniques for optimizing fuel burn during all phases of flight. It's important to note that implementing these fuel efficiency techniques depends on many factors, and only the pilot can make the ultimate decision on whether they can be safely applied.
Fuel economy initiatives during the briefing or at the gate
Pilots remain responsible for deciding how much fuel they put in their aircraft and may add Discretionary Fuel, also known as Pilot Extra Fuel, which comes on top of all other reserves (contingency fuel, holding fuel, alternate fuel…). The information available at the briefing stage is a crucial element in the decision-making process for carrying discretionary fuel.
💡Pro tip
To support you in the decision-making process, your ground teams might share statistics about flight plan accuracy and pilot discretionary fuel usage (with percentiles). This helps decide the best amount to take based on other pilots’ experience on the same route and in similar conditions.
More about it >>> Reducing pilot extra fuel without compromising safety
Eco-flying techniques during taxi-out
Shutting down one engine during taxi is a safe and widespread best practice to save fuel. Although not as popular as Engine-Out Taxi-In (EOTI), Engine-Out Taxi-Out (EOTO) is practiced by many airlines on a wide range of aircraft, especially during long taxi times.
Engine-Out Taxiing requires more anticipation compared to taxiing with all engines operating.
ℹ️In just 5 minutes of single-engine taxi, a B777 will save 65kg of fuel.
💡Safety tip
Ensure that this procedure is documented in Company SOPs, including limitations and required conditions
Once engines are running, consider shutting down the Auxiliary Power Unit (APU).
More about it >>> How to track your APU fuel burn on the ground
Fuel-saving actions at take-off
Optimizing fuel consumption during the climb phase
Once airborne, flaps and slats should be retracted as soon as possible within safety limits. This best practice is called Reduced Acceleration Altitude (RAAL). Some airlines have reduced flap retraction altitudes to 1000 feet AGL or even lower depending on the aircraft type (NADP2 procedure). Reduced flap retraction altitude is even more important when higher flap settings are used for take-off.
Boeing claims that the fuel saved by flying an NADP2 procedure vs an NADP1 procedure is 67 kg on a Boeing 737-800 with winglets and 197 kg on a Boeing 777-200ER.
💡Pro Tip
When applying reduced acceleration altitude, pay attention to the noise abatement procedures applicable at the airport. Many large airports, especially in Europe, prevent accelerating before 3,000 feet (ICAO calls this NADP1).
More about it >>> Why lowering aircraft acceleration altitude improves fuel efficiency?
Aircraft applying Continuous Climb Operations (or CCO) employ optimum climb engine thrust and climb speeds until reaching their cruising levels. This results in time being spent at more fuel-efficient, higher cruising levels, hence significantly reducing fuel burn and lowering emissions and fuel costs.
In-flight fuel optimization during cruise
Reducing fuel burn during the descent & final approach
Whenever possible, plan to fly a Continuous Descent Approach (CDA) or Continuous Descent Operations (ICAO name). With accurate descent winds loaded, the FMS computes a largely accurate, efficient descent profile and an optimum Top of Descent (TOD). If you choose to descend early or late or modify speed and descent rates the benefits shall be reduced, and you should update the FMS in such cases. Starting a descent profile too early or too late will generate significant extra fuel burn.
Use the most efficient speeds, continuously trading speed for altitude or vice versa as required unless specific speeds are assigned. Avoid the use of speed brakes as much as possible. Energy management should always be kept in mind.
Even when no CDA procedure is published, it is often possible to perform CDAs at most airports. Sharing statistics on CDA application can help pilots request them when they are most likely to be granted.
Where allowed (airport/ATC regulations, company SOPs, current conditions) and if the airport is not too congested, a Visual Approach or a Short Approach may be considered instead of sticking with the announced standard arrival procedure (STAR).
Some airlines have developed Precision Approaches (also known as PBN or RNP-AR), in which the aircraft, the airline, and its pilots are certified to follow a GPS-designed procedure.
By optimizing the approach profile specifically, they can increase safety and reduce fuel consumption. Within the safety limits of current conditions and keeping in mind company SOPs for stabilization criteria, avoid deploying flaps and landing gear too early to avoid wasting energy; this Best Practice ties in with the general concept of Low-Noise, Low-Drag approaches.
Fuel efficiency procedures for landing
Reduced Flap Landing will reduce fuel burn and decrease noise and emissions where it counts- around the airport.
Operational conditions apply, of course, and will be part of the SOPs. Reduced-Flap Landing will see an average 5 knots higher touch-down speed and an extra landing distance of around 500 feet (for A320/B737). Several airlines have made reduced flap landing procedures standard except for high-altitude airports, contaminated runways, or airports with short runways.
Use Idle Reverse Thrust after touchdown. Again, operational conditions apply and will be part of the SOPs. Advantages include extending engine life thanks to:
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one less high-power cycle,
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less foreign object damage (FOD),
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slower engine performance deterioration,
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increased reliability
Other benefits include lower fuel burn and noise, passenger comfort, and operationally, a lower cooling time requirement before shutting (an) engine(s) down for Engine-Out Taxi-In.
Reducing aircraft fuel use during taxi-in
When conditions allow, many pilots use the Engine-Out Taxi-In (EOTI). Well-designed SOPs are required, as well as training. Runway crossing, taxiway/ramp surface condition and gradient, last turn angle, and aircraft constraints (as regards to which engine can be shut down) are factors, among others, to be considered when applying Engine-Out Taxi-In.
Anticipation is key in keeping the aircraft moving. The main advantages are lower fuel burn and noise and, especially with twin-engine aircraft, lower brake wear.
Related content >>> What you need to know about Engine-Out Taxi-In
Unless you perform an Engine-Out Taxi-In and the manufacturer’s procedure mandates to switch the APU on, start the Auxiliary Power Unit as late as possible when you arrive at the gate (APU during Taxi-In).
Sharing fuel-saving insights during debriefing
You've completed this introduction module!
Thank you for reading this introduction module on fuel efficiency procedures. As you’ve seen, every stage of a flight offers opportunities to optimize fuel use while maintaining the highest safety standards.
Go further by exploring in detail each technique.
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