Taxi Time Reduction

This case study presents initial findings from the deployment of Assaia’s ApronAI, Turnaround Control solution at one of the fastest growing airports in the US. Airports’ growth brings typical challenges related to capacity. The examined airport is a classic case because there is little room for physical expansion and the only options that are available are extremely costly as major infrastructure works are required.

As a result of limited capacity and high traffic, the airport can get very busy, especially at peak hours. One result of this has been that inbound flights often have had to hold before their gate becomes available. The preferred location to hold an aircraft is in the movement area between the two parallel runways. If it is known that the target gate of an arriving aircraft is not yet available, the ramp control tower thus asks Air Traffic Control (ATC) to hold the aircraft there until the gate becomes available. Then the flight is cleared to enter the non-movement area and is guided by Apron Control to its gate.

However, if information about gate availability is not known in advance, a flight might be directed towards the non-movement area even though its gate is not available. As there is no space in the non-movement area for holding, in this case Apron Control lets the aircraft move around the non-movement area not to block any other traffic. This means that an inbound plane is taxiing in circles until its gate becomes available. This procedure obviously increases aircraft fuel consumption and thus imposes unnecessary cost to the airlines as well as negatively impact airport sustainability and noise levels. Furthermore, this procedure also often includes handovers of the control of the aircraft between Apron Control and ATC. In an already busy situation this introduces additional workload for traffic controllers and therefore brings unwanted risk.

Set Up

Besides helping airlines to enhance their on time departures through real-time insight into ongoing turnaround operations, the Turnaround Control solution also provided a solution to reduce taxi times of inbound aircraft.

On the 19th of May 2021, the airport took the Turnaround Control solution into production for 44 gates. The map view of the application shows the users in the ramp tower a real-time overview of gate occupancy. Furthermore, by clicking on any of the gates the apron controllers can get a detailed view of the turnaround progress and estimate how much time is left before the aircraft will leave the gate. This information, which was not available before, gives the controllers a better understanding of which gates will be available when. It enables them in advance to decide which aircraft should be held between the runways in the movement area and which aircraft can directly enter the non-movement area to taxi to their gate.

This implies, with more aircraft being held in the movement area, that less aircraft enter the non-movement area while their gate is not available. And thus reduces the cases where aircraft are taxiing around and unnecessarily burning fuel and keeping ground controllers busy with handovers.

Even though the first release of the Turnaround Control application already made a big impact (see next section), the best is yet to come! In October 2021, during the second release, the solution was rolled out across another 21 gates covering almost the entire airport. Furthermore, the Predicted Off-Block Time (POBT) feature will be implemented too. The POBT is a prediction that uses a wide range of data sources in order to continuously predict when an aircraft is going to go off-block. This proactive and predictive information will further enhance Apron Controllers’ real-time insight and enable them to make even better decisions than before.

Results

In order to validate and quantify the positive impact of the introduction of the Turnaround Control solution, we investigated taxi-in times of arriving aircraft. Better insight into gate availability should lead to less aircraft being allowed into the non-movement area and spending time there taxiing around. We found that shortly after the Turnaround Control solution had been implemented, average taxi-in times decreased.

Figure 3 shows the average difference in taxi-in times between Assaia and non-Assaia gates over time. Since many external factors can influence the taxi-in times, we have chosen to take the taxi-in times to non-Assaia gates as a baseline and show the difference with Assaia gates. You can see that before the implementation of the Turnaround Control solution, taxi-in times were higher at the Assaia gates (hence the positive values). After the implementation, this difference decreased.

In order to quantify the results, we compared taxi-in times for aircraft headed to gates where the system is active versus gates where the system is not active. In line with our expectations, we found that whereas taxi-in times increased for aircraft heading to non-Assaia gates, they decreased for aircraft heading to Assaia gates.

Again, if we take the taxi-in performance on non-Assaia gates as a baseline we can conclude that the introduction of Turnaround Control reduced taxi-in times on Assaia gates with 49 seconds.

Based on average aircraft operating costs as provided by the FAA this reduction in taxi-in times results in a cost saving for the airlines of $122 per flight, or an annual total saving of more than $25 million for all flights at the examined airport. Furthermore, these reduced taxi times also reduce CO2 emissions by 13kg per flight or 2.6 million kgs of CO2 per year.

If you are eager to learn more about this particular case study or about different ways in which Assaia’s ApronAI software can create value for your airport or airline contact us at info@assaia.com or via the website form.