CASE STUDY: Flight path optimization makes Volotea eco-efficient
Author: Luis Fernandes, Fuel Efficiency Manager, Volotea and David Rytter, CEO, AVTECHSubscribe
Luis Fernandes, Fuel Efficiency Manager, Volotea and David Rytter, CEO, AVTECH share the experience of leveraging a flight crew’s profile optimizing solution for eco-efficient flying.
The plan for this case study is to give readers an overview of the flight path optimization tool adopted by Volotea and what it provides for pilots and the airline. But, before going into that, it’s always useful to know something about the subject of a case study, in this case, Volotea.
Volotea is an airline that connects mid- to small sized cities across Europe with an all-Airbus fleet of 41 aircraft operating from 19 bases. There are more than 1,600 people employed in the business and Volotea flies around 365 routes carrying 9.5 million passengers a year (figure 1).
Looking at a history of Volotea’s growth (figure 2) we can see that from conception in 2009, the airline made its first flight in 2012.
The initial fleet used Boeing 717 aircraft but in 2016, started to change to Airbus starting with A319s. Then in 2021, after the COVID pandemic period, the Boeing 717 fleet was replaced with Airbus A320s.
The airline has recently opened its latest base in Lille plus, in March 2022, Volotea passed 40 million passengers carried in the ten years since launch.
AVTECH designed ClearPath to be an advanced in-flight optimization capability that integrates very smoothly into the user airline’s existing operation (figure 3). The system operates as a ground-based service and utilizes already installed technology and therefore requires no investments.
Airlines can utilize the equipment they already have, and pilots can continue to fly in the same way they currently do, interacting with the FMC (Flight Management Computer) as usual. ClearPath calculates a cost-optimal flight path based on the cost index, aircraft gross weight and route, as downloaded from the FMC in-flight.
As the service is ground based, it is able to perform its flight optimization calculations with unlimited computational resources and full access to the latest accurate high-resolution weather forecasts (figure 4).
The service is fully automatic and starts by collecting data from the flight such as active route, Aircraft gross weight, the selected speed or cost index.
Using this data, a four-dimensional flight trajectory is calculated and used to retrieve the latest high-resolution weather forecast for the specific flight path. ClearPath then calculates the cost optimal flight profile by comparing all different flight level options to fly from point A to point B.
The resulting optimal flight path is uplinked to the cockpit in real time, together with information about estimated savings. This means that it’s entirely hands-off for the pilots to get this information and then it’s up to them to use it to optimize the flight.
For each flight, the service automatically looks at how the ClearPath optimized profile compares with the fuel burn time of flying the planned flight profile (OFP) altitude steps. This fuel saving potential is typically around 2.5 percent, however this varies with airline and operation.
How the system works
After take-off, the system monitors the flight and automatically uplinks the information to the pilots. ClearPath requests certain parameters from the Flight Computer, such as the active route, the cost index and the weight of the aircraft. The solution does a 4DT (four-dimensional trajectory) calculation using the high-resolution weather forecast from the Met Office. This is a full 10k resolution weather forecast with hourly temporal resolution, compared to the standard 140km resolution weather forecast that you see in flight planning. The solution works with the full trajectory and does the ClearPath optimization, calculating the most cost optimal flight profile. The system then calculates what altitudes will give this flight, in this atmosphere with this weight, the most cost-optimal flight profile. Creating a short message uplink to the cockpit.
How ClearPath supports pilots
Figure 5 shows a typical ClearPath message, uplinked to the pilot. This message can be tailored to the airline preference.
Here we see a great example of ClearPath in action on a Boeing 787 flight over the Atlantic.
In the illustration we see the operational flight plan profile as a blue line with a typical planned step climb towards the end of the flight as it’s coming in over Europe. In the same picture we can also see a jet stream core over Europe with beneficial winds on lower altitudes.
On the right side of the screen, we can see the ClearPath text message that the pilots received during climb at roughly FL150. This message contains the optimal initial altitude and steps for this flight, as calculated by ClearPath for the actual aircraft weight and cost index 15. The ClearPath advice is seen as a green line in the illustration.
As this flight is operated at a low cost index of 15, meaning fuel is prioritized over time, the cost optimal flight path is to step down into the more beneficial wind layers. The pilots see that if they can follow the optimal path, they will achieve a fuel saving of 661 kg and a time delay of 5 minutes, as compared to flying the planned profile. This is a fuel saving of 1.7% of the entire cruise fuel, at the cost of a few minutes later arrival on an 8- or 9-hour flight. On this flight we know that the pilots also followed the optimal path perfectly and after landing we received a report that confirmed the savings.
By running the service automatically (figure 6) after take-off not only does it ensure that every flight gets optimized it also ensures that the optimization is based on the actual aircraft parameters as extracted by the service from the flight computer.
ClearPath, as compared to other services on the market, puts very little workload on the pilots as it is hands-off and fully automated. As the pilots receive the optimization automatically all they need to do is to coordinate with air traffic control and fly the recommended profile. We have seen in airline case studies that this leads to a high pilot compliance which maximizes the value for the airline.
We just launched a brand-new feature in ClearPath that we think pilots, crew and passengers will like (figure 7).
ClearPath now has detection, notification and avoidance of hazardous turbulence built right into its optimization (figure 8). From now on ClearPath will inform pilots about hazardous turbulence enroute and suggest how to avoid it in the most cost optimal way. And it’s fully automatic. This is based on a detailed high resolution EDR turbulence forecast from the UK Met Office. With the demonstrated accuracy of this weather information, we think this new feature will be a game changer.
The ClearPath report now lists in a separate section any turbulence and temperature exceedances along the planned flight profile, complete with start point, end-point and intensity and the ClearPath optimization will now clearly state when optimal flight levels are limited by temperature or turbulence. ClearPath always shows the most cost-optimal altitudes and step positions to avoid these hazards.
The accuracy of this weather information now truly makes this new feature a game changer for pilots and airlines. The text-based version of ClearPath (figure 9) really makes it easy to get started and get it into the cockpit and used by the pilots while the pilots continue to interact with the FMC.
There is no need for additional Apps or to introduce a lot of new things, Pilots continue to operate in the same way but now have better guidance.
The ClearPath service can also be integrated into AVTECHs ProFlight EFB app (figure 10) where the pilot will be able to interact a bit more, put constraints on the optimization and more. However, the optimization remains the same advanced optimization in the background.
AVTECH’S CLEARPATH IN VOLOTEA
AVTECH’s ClearPath service implementation timeline with Volotea. Can be seen in figure 11.
AVTECH and Volotea first met in 2019 at an Aircraft Commerce, Aircraft IT conference. However, because of COVID, any progress on the project stopped but was re-activated in February 2021. The trial started July 2021 and was commenced using six A319 aircraft. The application was tested over four months until October 2021, and was afterwards fully implemented to the entire fleet.
Based on pilot feedback the system has been customized slightly. ClearPath now uses Volotea’s actual takeoff weight including last-minute changes, making the optimization much more accurate.
Volotea chose to do a survey amongst their pilots in order to verify the service utilization and how much of the potential savings actually could be achieved. Since Volotea has a lot of shorter routes, it was never going to be possible to realize the full saving potential.
In the survey the pilots were able to offer feedback during around 6,200 flights and pilot responses were obtained in respect of 64 percent of those flights (figure 12).
The answers told the airline that 62 percent were able to fully operate the route according to the recommendations from ClearPath optimization. In 31 percent of the cases, ATC were unable to grant the pilots requests, and for the remaining seven percent of the flights there were performance limitations or other unspecified reasons why the pilots did not used the optimized flightpath.
In respect of the 62 percent that were able to use the optimized flightpath, only ten percent achieved no savings with ClearPath versus the OFP. With a further 22 percent only being partially approved (perhaps not all steps in the cruise were approved) while 68 percent were able to fully use ClearPath.
Out of the 62 percent of flights that used ClearPath, 68 percent of those were able to take full advantage of the service. Another 22 percent were able to take partial savings from the service. It all adds up to an actual saving of 49 percent of the savings potential (figure 13).
ClearPath gives direct fuel and time savings.
In Q1 2022 we could see an increased fuel saving as the months progressed. In January 2022, the A319 fleet had an average saving of 4.1 kilos per flight. When the system was implemented for A320 in February, the average flight hours per flight increased. In March, savings were even higher with the longer cruise times of the A320 fleet giving them a saving of 7.5kg per flight and the A319s returning savings of 6.1kg per flight. Volotea was able to realize more value from the system as the year progressed.
When it comes to time saving, we could see 14 seconds time saving per flight in January. Increasing the coming months to around 25 seconds per flight on the A319 fleet and around 11-16 seconds per flight for the A320s.
When adding both time and fuel savings, summarizing the total direct fuel savings and seconds per flight shown in the table on the right, you can see the overall value of 18kg per flight obtained from using the AVTECH ClearPath system.
Looking at the savings per route, figure 14 shows what Volotea expects to be the most optimal routes using ClearPath.
An interesting fact that you can see in the graph above are the flights with quite short cruise phases where verified savings could be achieved. For instance, the flight from Nantes (NTE) to Strasbourg (SXB), a short French domestic flight, achieved an average savings of 22.8kg. While our expectation was to have high savings on flights with longer cruise phases, the analysis revealed valuable savings on the shorter routes as well.
Looking at savings by flight hours per flight between 0.8 and less than one hour, there was an average saving of 22kg per flight. Regarding the longer cruises, between 3.4 and 3.5 hours per flight, there was an average saving of 27kg per flight; the difference is not as big as had been initially expected.
Taking into account that savings gained will vary according to the airline’s route mix, for Volotea there has been an overall saving of 1 percent of the total fuel burn (figure 15).
The conclusions that can be extracted from all of the above data from Volotea was that, while savings are not directly related to the cruise length of a flight, the greatest savings have been gained on longer routes. That does give rise to some questions. Is the flight planning system sufficiently accurate, is it optimizing the flight? Also, is the baseline of the OFP enough? Volotea tested ClearPath against the FMS to obtain more accurate results and to check whether the system is working, as well as to isolate individual initiatives. The ClearPath initiative’s savings can then be calculated. From that, it was revealed that 0.81 percent of the total fuel consumption had been saved in Q1 2022. This means the real result that Volotea has obtained with the system (1 percent against the OFP base line) turned out to be 0.81 percent of total fuel consumption, which is regarded as a very good result during that first quarter.
During Q2 and the busy summer season, the skies are more crowded and, as a consequence, ATCs are less flexible to allow pilots to change flight levels. Despite this it is likely that AVTECH ClearPath will save Volotea around €3 million of fuel costs per year.
The busier the airline industry becomes, and as fuel prices increase, more airlines will implement fuel saving services. Which in turn will add to the workloads of ATCs as more pilots request re-routes and level changes. Will that reduce the benefit airlines can gain from these systems? AVTECH’s ClearPath service is constantly communicating with the pilots and knows where the airplane is and where it is going. This is a great opportunity to improve information sharing, and for pilots to start planning ahead and to notify ATC well in advance when requesting new altitudes. Despite busy airspaces, AVTECH has already seen that airlines using ClearPath have been able to utilize a big part of the potential savings.
Luis is an aeronautical engineer who started working at Volotea in 2016 as Safety Data Manager managing and analyzing flight data to maintain safety performance targets and reducing the risk within operations. During the case study in 2022 he was the Fuel Efficiency Manager developing Volotea’s fuel efficiency and sustainability program and applying new data technologies to improve the detection of inefficiencies and drive Volotea to fuel consumption excellence.
David is a pilot and aerospace engineer that has been working in Aviation and IT since 2010 when he started at AVTECH. Over the years he has engaged in software and product development projects through various roles as product owner, project manager, solution architect and deployment manager. David enjoys working in close cooperation with customers. From 2015 to 2019 he was AVTECHs CTO and since 2020 he manages the company as CEO. David is the holder of a commercial pilot license from Scandinavian Aviation Academy and a MSc in Aerospace Engineering from KTH Royal Institute of technology, Stockholm.
Volotea is one of the fastest-growing independent airlines in Europe serving more than 100 airports from 19 European capitals with its fleet of 41 Airbus A319 and A320. To date, Volotea has launched over 50 sustainability initiatives that have driven a reduction in carbon footprint per passenger and kilometre, and has been working on developing emission-free alternative technologies, operating Airbus’ internal shuttle service with 34% of sustainable aviation fuel.
AVTECH, specializes in tailored information to the cockpit with easy, automated and inexpensive improvements in FMS optimization. The result is a reduced fuel burn and CO2 footprint, while improving safety and comfort by avoiding turbulence. AVTECHs ClearPath service provides an automated optimization and decision support to each flight based on real-time flight parameters, and the latest high resolution weather modelling. ClearPath now also has detection, notification and avoidance of hazardous weather built right into its optimization. The service informs pilots about hazardous turbulence enroute and suggest how to avoid it in the most cost optimal way.