Reducing CO2 Emissions in Daily Operations
Operational Methods and Other Measures
The JAL Group is conducting various activities in workplaces, such as reduction of aircraft weight and regular engine washing to improve fuel economy. Specifically, we are implementing CO2 emission reduction initiatives through the cross-organizational Fuel-Saving Project and implementing the PDCA cycle to monitor and share progress in order to achieve our goal.
During regular maintenance
Large quantities of waste water are discharged when washing aircraft or repaired components and plating components as part of aircraft maintenance. JAL collects the waste water in company treatment facilities, remove harmful substances, and treat and recycle water in order to use valuable water resources effectively.
Water treatment facility-OutsideWater treatment facility-Inside
Aircraft engines get dirty as they ingest and accumulate airborne particles in flight, which in turn reduces fuel efficiency and increases CO2 emissions. The JAL Group regularly washes the engine interior to remove particles that have adhered to internal components during flight. This contributes to approximately 1% recovery of fuel efficiency. Engine washing is performed on the Boeing 777 (PW4000 engine), the 767 (CF6 engine), and the 737-800 (CFM56 engine) every 200 to 300 days, resulting in CO2 emission reduction of approximately 14,000 tons per year (estimate for fiscal 2012).
While Parked in Spot
Reduce APU usage
Aircraft need power and air conditioning for cabin lighting even while parked on the ground. Therefore, an auxiliary power unit (APU) is installed in the tail of many large passenger aircraft. The APU is a small jet engine providing power and compressed air. It runs on fuel, and therefore emits a certain amount of CO2. APU is essential for starting the engines for pushback, during which an aircraft is pushed backwards away from the spot by a towing truck to the taxiway that leads to the runway.
At departure, a delayed APU start to shorten APU usage can contribute to reducing CO2 emissions. When the APU is not used, power and air conditioning is supplied by a ground power source, which is more efficient than the APU and effective in reducing CO2 and noise emissions, as the APU is designed for installation on aircraft.
The JAL Group strives to shorten APU usage and reduce CO2 emissions during pre-flight preparations without compromising passenger comfort through the coordinated teamwork of its flight crew members, maintenance engineers and ground staff. For example, 100 kg of CO2 emissions can be reduced at Haneda Airport by switching power and air conditioning supply from the APU of a Boeing 777 to a ground power source for 10 minutes.
The auxiliary power unit (APU) is installed in the tail.
Close window shades
When aircrafts are parked in the spot, window shades (sunshades) are lowered depending on the weather and the time of day, with cooperation from passengers. Air-condition is supplied from the APU installed in the tail or a ground power source to maintain comfortable cabin temperatures. However, as the APU runs on fuel, it emits CO2. Therefore, by lowering window shades and maintaining appropriate cabin temperatures, air-conditioning use can be shortened, thus reducing unnecessary CO2 emissions.
Window shades are lowered depending on the weather, etc.
Reduce aircraft weight
Like cars, aircraft consume less fuel and emit less CO2 when they are lighter. Since 2005, we have taken steps to reduce onboard weight such as tableware, and since 2014, have progressively introduced lightweight containers. The lightest product weighs approximately 60kg compared to previous products which weigh around 100 kg.
Advanced route planning technology
User Preferred Routes (UPR) are used in operations on routes connecting Japan and Hawaii, Australia, and the west coast of North America (Los Angeles, San Francisco, Vancouver). Instead of following the conventional approach of flying along predetermined flight routes set by air traffic controllers (ATC), the airline is free to decide the flight path according to weather conditions and other factors under certain restrictions. This was made possible through advancements in navigation system precision in recent years to pinpoint an aircraft’s position in the air. As a result, by operating in optimal weather conditions, flight times can be reduced, leading to reductions in fuel consumption and CO2 emissions. We actively use this operational method to select routes and altitudes, for example, to take advantage of a tailwind or avoid turbulence. These advanced operational methods have contributed to CO2 emission reduction of 3,000 tons per year for the entire JAL Group.
Example of UPR
Blue line: Example of UPR from Narita to Honolulu
Red line: Conventional flight paths
Ascent with early acceleration
Ascending after takeoff while accelerating from an earlier point is effective for reaching cruising altitude earlier in the flight and reducing fuel consumption. Therefore, JAL is actively utilizing this approach to reduce CO2 emissions.
During the Descent Phase
Reduced air resistance
Setting flaps at shallow angles and delaying the timing for lowering the wheels and flaps, while maintaining safety, is being conducted to minimize air resistance in flight and reduce CO2 emissions.
Continuous Descent Operations
Aircraft climb and descend stepwise with level-off portions in-between according to instructions of ATC, resembling a staircase (figure below). In the descent phase to prepare for landing, the aircraft descends to a lower altitude by operating at lower engine thrust or idle thrust. Then the pilot waits for instructions from ATC to descend to the next altitude. During level flight, the pilot must increase power to keep the aircraft level. Long segments of level flight increase fuel consumption and CO2 emissions. To eliminate such inefficiencies, the descent path is identified in advance through ATC-pilot communications and the pilot performs the continuous descent approach along the glide slope to the runway. At Helsinki International Airport and Kagoshima Airport, where continuous descents are in operation during specific hours, the JAL Group actively uses this process. As a result, in addition to CO2 emission reduction, CDOs reduce the frequency of ATC-pilot communications and pilot workload, contributing significantly to flight safety.
The wings of an aircraft change shape at the landing phase so that the approach to the ground can be flown more slowly to maintain safety. At this time, flaps are extended from the rear edges of the main wings. This enables the wings to produce more lift at slower speed, but increases air resistance (drag) at the same time. Flap angles differ depending on aircraft type. A longer flap will produce more lift but also more drag because of the increased projected area. When large angle flaps are used, higher engine thrust must be maintained, which increases fuel consumption and CO2 emissions.
Therefore, when conditions and safety allow it such as when landing on a long runway, the pilot will select a smaller flap angle (reduced flap) to perform the final approach until touchdown, which will contribute to reducing CO2 and noise emissions on the ground.
Delayed Flap & Gear
Landing gears (arrows) and flaps (circles), which are essential mechanisms for landing, produce large amounts of drag, and to overcome the drag on the aircraft, the engines need to produce extra power. Flaps and landing gear are indispensable at landing, but for aircraft, extension of landing gears and flaps produce more drag than in cruise, resulting in greater fuel consumption and CO2 emissions.
To reduce CO2 emissions, the pilot delays flap and gear extension depending on conditions at landing.
Photo: Hisao Furugaya
After landing, the aircraft decelerates appropriately on the runway, exits the runway and proceeds to the specified taxiway. Reverse engine thrust and the brakes in the landing gears are used to slow down, but the thrust reversers have the greatest effect when decelerating at high speeds immediately after touchdown. The engine’s mechanical structure diverts thrust so that it acts against the forward travel of the aircraft and provides deceleration. This is powered by rotations of the engine. The greater the reverse thrust that is applied, the faster the engine rotates. If conditions allow at landing, such as a strong headwind or a dry runway, the aircraft can decelerate by using reverse thrust at idle power. Therefore, to reduce CO2 emissions, the pilot determines landing conditions and applies reverse thrust if sufficient deceleration can be achieved.
Photo: Hisao Furugaya
Reverse thrust after landing (engine cowls open up)
Thrust, generated by the engine, is the force which operates airplanes. This thrust is extremely powerful and can move the airplane forward even when the throttle is idling. As the weight of the airplane is lighter after consuming large amounts of fuel, after landing away from the runway and on the taxiway, the pilot will shut down a single engine while moving to an open spot, thus reducing excessive CO2 emissions.
Initiatives Other Than Operational Initiatives
Improvement of Wing Tips and Fuselage
The tips of wings were straight on previous aircraft but by curving them, wing tip vortices that occur at the wing tips can be reduced as well as drag, thus improving fuel efficiency and reducing CO2 emissions.
As the benefits of winglets on fuel economy was expected, the JAL Group revamped nine Boeing 767 aircraft operated on long-haul routes. On recent aircraft, the Boeing 737-800 and 787and the Airbus A350 have winglets or wing shapes that are equally effective.
Engine Upgrades and Replacement
JAL Group Boeing 787 aircraft are fitted with General Electric GEnx-1B engines. Various design changes called PIP (Performance Improvement Program) have been undertaken to improve engine performance. There are currently two types, PIP-1 and PIP-2.
The PIP-2 engine is an improved version of the PIP-1 engine with significantly improved designed parts. By improving the low-pressure compressor, high pressure compressor, combustor and high-pressure turbine, fuel efficiency has improved approximately 1.2% compared to the PIP-1 engine.
The JAL Group plans to upgrade all PIP-1 engines to PIP-2 engines, in consideration of environmental impacts of engines.
GEnx-1B engine installed on the Boeing 787
Investments to reduce CO2 emissions
The JAL Group continues to investment in CO2 emissions reduction. Currently, the most effective measure is renewal of aircraft to more fuel-efficient aircraft. In FY2014, we introduced five fuel-efficient 787-8's, and retired five 777-200, 767-300, and 737-400 aircraft, and in FY2019 we introduced A350. We will continue investments for aircraft renewal.
introduce LED lighting in maintenance facilities
Improvement of On-time Departure Rate
When pre-flight preparation such as passenger boarding and cargo loading are completed, the pilot requests clearance to leave the spot and departure clearance from ATC by radio. Only after the pilot is given departure clearance, the aircraft can start to taxi to the runway. Basically, clearance is issued on a first-come, first-served basis. In addition, in the en route phase, the pilot must make requests for any change of route or altitude due to weather conditions or turbulence before initiating it. This is also processed on a first-come, first-served basis. Although aircraft are operated according to the flight schedule, on-time departure will not only ensure on-time arrival at the destination but also greater passenger comfort by selecting optimal altitudes with less turbulence and also environmental benefits from less fuel consumption by selecting routes and altitudes with a better tailwind.