Passenger Boarding Strategies

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1		Luís Pinto Ferreira	--	1715	2024-02-08 09:51:48	\|
2	Reference format revised.	Lindsay Dong	Meta information modification	1715	2024-02-11 12:26:14	\|

This entry is adapted from the peer-reviewed paper 10.3390/su152316476

Boarding time constitutes a critical element of turnaround time, which is used to measure the efficiency of airline operations. Therefore, to reduce boarding time, it is imperative to reconsider traditional passenger boarding strategies to make them more efficient. Different techniques have been used to address the problem, including the following: (1) simulation, (2) analytical methods, and (3) experiments in the aircraft.

boarding strategies turnaround time sustainability

1. Introduction

Aircraft have become an essential means of transport and, as such, air travel has increased dramatically over the last decades ^[1]. This demand for air travel has caused enormous competition in the aviation sector with a view to reducing costs, increasing efficiency, and meeting customer satisfaction ^[2]^[3]. To avoid congestion at airports, as well as to enhance operational efficiency, airlines have been compelled to reduce their turnaround time ^[4]. This is because airlines only generate revenue when planes fly, as having aircraft on the ground is considered unproductive ^[3]^[5]. The turnaround time mainly consists of passengers deboarding, cleaning, and passengers boarding; however, the most critical point resides in the boarding activity. It is estimated that a 1 min reduction in boarding time represents a saving of $30 United States Dollars (USD) for each turnaround ^[2]. Nevertheless, the process of boarding passengers on an aircraft is not always carried out in the best possible manner ^[6], with airline companies having limited control over passengers ^[5].

To reduce boarding time, the amount of interference amongst passengers should be minimized. This means that airlines must adopt an efficient boarding strategy to control the order in which passengers enter the aircraft ^[3]^[5]. The literature addressing strategies to improve the boarding process is still rather scant ^[2]^[3]^[5]^[7]. Boarding processes, if executed incorrectly, can lead to delays and additional costs for the airline ^[8].

In the case of well-implemented strategies, the three main parts involved—airlines, airport operators, and passengers—ultimately benefit from this reduction in boarding time ^[6]. Additionally, passengers valorize solutions that minimize waiting time at the boarding gate ^[9].

2. Passenger Boarding Strategies

Marelli et al. ^[10] define the turnaround time of an aircraft as “the time required to unload an airplane after its arrival at the gate and to prepare it for departure again”. During this time, several events occur, namely: deboarding and boarding of passengers, unloading and loading of luggage and/or cargo, refueling, crew replacement, cabin cleaning, and kitchen maintenance ^[1]^[3]^[5]. The study developed by Van Landeghem & Beuselinck ^[4] concluded from interviews that the turnaround time can range from 30 to 60 min. Theoretically, the activity of deboarding requires approximately 10 to 15 min, cleaning about 15 to 20 min, and boarding approximately 10 min. Yet, in practical terms, the latter is almost always exceeded, often reaching 30 min ^[4]. Average boarding speed has seen a drop in the last 30 years of about 55% ^[10]. This decline in the efficiency of the boarding process can be attributed to the more generalized use of carry-on baggage, a greater convenience on the part of passengers, and passenger demographic data, as well as the strategies implemented by an airline and the flight distance ^[2]. Lower boarding rates will certainly lead to an increase in boarding times.

The main cause of delay in passenger boarding is interference among passengers. Soolaki et al. ^[3] define this interference in boarding as an instance when a passenger blocks another passenger or the aisle itself, or when passenger access to a seat is obstructed. Interference can be classified into the following two types: aisle interference and seat interference. Aisle interference occurs when passengers wish to reach their seats and are blocked in the aisle by other passengers who have stopped in front of them, usually stowing hand luggage in the upper lockers. Seat interference occurs, for example, when the window passenger wishes to take his seat and must ask the passenger already sitting in the aisle seat or in the middle to get up and allow their passage. According to Delcea et al. ^[11] and Cotfas et al. ^[12], there are four types of seat interference that passengers are faced with during their journey. Moreover, according to the same authors ^[11]^[12], the greatest interference delay is generated by type 1, during which the passenger with a window seat is required to wait for the other two passengers to move out before occupying their corresponding seat. The second longest delay, generated by the fact that a window seat passenger must wait for the occupant of the middle seat to clear the way is presented as a type 2 seat interference. Types 3 and 4, which refer to the passenger in the middle or window seat waiting for the passenger in the aisle seat to clear the way, both generate an identical delay time, which is still shorter than the first two types.

To reduce passenger interference and, in turn, boarding time, several boarding strategies have been considered. The main boarding strategies used by airlines are summarized as follows ^[7]^[13]:

Random: One single boarding group of passengers randomly accesses the plane’s entry point. This procedure is often used as a point of reference for subsequent comparison with other boarding methods ^[13] (see Figure 1a).
Back-to-Front: In this method of boarding, the first passengers to board are those in the last rows of the plane. Boarding continues until the front rows are reached. The rows on the plane are divided into zones (or blocks). Any number can be attributed to these zones, from two to the total number of actual rows. Despite being a straightforward strategy to implement, it can easily result in inefficiency, as congestion often occurs in the boarding queues ^[13] (see Figure 1b).
Outside-In: also denominated as WMA or Wilma (Window–Middle–Aisle), this method first boards passengers who have window seats and, subsequently, those in the middle seats, finally followed by passengers sitting next to the aisle. This method has so far led to very efficient boarding times, eliminating seat interference ^[5] (see Figure 1c).
Reverse Pyramid: In this method, the boarding of passengers occurs from the external rear to the inner front section of the cabin. In fact, it combines the back-to-front and outside-in strategies, so that simultaneous boarding occurs on the aircraft from back-to-front and from the outside-in. During this procedure, the first passengers to board are those with a window seat and a middle seat located at the rear of the airplane. Passengers with an aisle seat at the front of the plane are the last to board. This strategy has proved to be an efficient method and is implemented by American West Airlines ^[5] (see Figure 1d).
Blocks: In this case, the rows in an aircraft are divided into zones or blocks, each consisting of several rows, with each passenger assigned to a designated block. This method first boards passengers seated in the last rows (block 1) and then passengers that are in the front rows (block 2). Subsequently, the order proceeds once again, beginning with the farthest zone (last unoccupied rows), then the front rows, and so forth. The positive aspect of this procedure is that when passengers enter the aircraft from the back and front, they do not block each other’s paths ^[5] (see Figure 1e).
Steffen: The Steffen method organizes passengers in a specific order. Boarding is carried out from back to front and from the windows to the corridor. Passengers occupying a specific seat in the row are seated two rows from each other, in the same seat position (e.g., 12F, 10F, 8F, 6F, 4F, 2F). Firstly, on each side of the cabin, passengers are seated according to even and odd rows, occupying the window seats, then the middle seats, and, finally, the aisle seats ^[13] (see Figure 1f).
Modified Optimal: This method consists of boarding passengers in alternating queues, providing them with enough space to carry their luggage. Passengers are divided into four boarding groups. The first of these consists of all those passengers who will occupy seats in the even rows, which are limited to the right or left sides of the plane only. The second group includes all the passengers who will sit on the unoccupied side of the plane. The third and fourth groups consist of passengers occupying seats in the odd rows on each side of the plane ^[5] (see Figure 1g).

Figure 1. Illustration of the following boarding strategies ^[13]: (a) random; (b) back-to-front; (c) outside-in; (d) reverse pyramid; (e) blocks; (f) Steffen; and (g) modified optimal.

Several studies have already been carried out with a view to implement aircraft boarding strategies. Different techniques have been used to address the problem, including the following: (1) simulation ^[1]^[4]^[5]^[9]^[10]^[14]^[15], (2) analytical methods ^[2]^[3]^[16]^[17], and (3) experiments in the aircraft ^[13]^[18]. The study developed by Bidanda et al. ^[8], for example, reviews the literature dealing with the implementation of models aiming to optimize boarding processes, thus achieving maximum efficiency. A more extensive comparative study ^[6] considered previous and future research studies in this area. On analyzing the results found in the research pertaining to boarding strategies, the authors Jaehn & Neumann ^[6] concluded that simple methods such as random boarding are more effective than the most commonly used back-to-front strategy. Nyquist & McFadden ^[2] demonstrated that luggage restriction reduces boarding time. Qiang et al. ^[15] developed a simulation model in which passengers carrying more luggage are boarded first. Kisiel ^[14] looked into the potentially problematic issues of generalized strategies, more specifically those which concern the number of priority passengers involved. Ren & Xu (2018) ^[18] claimed that the absence of music during boarding reduces the time required for this activity. A study conducted by Schultz ^[16] proposed changing the aircraft’s infrastructure to reduce the number of interference events. Tang et al. ^[17] presented a boarding strategy that considers the characteristics of individual passengers. This study was one of the first to discuss the correlation between boarding time and the percentage of passengers carrying hand luggage and/or the number of priority passengers, using seven different boarding strategies. Although this study used the Airbus 320 aircraft in its analysis, this is simply a general example which can be applied to different aircraft. Another more recent study undertaken by Kobbaey et al. ^[19] implements independent agent-based simulation in order to evaluate the most widespread research pertaining to the boarding of individual passengers and groups. The aspects considered include luggage, walking speed, and passengers’ disrespect of required norms. The analysis also puts forward a new procedure to reduce delays in boarding. The research results point to an improved performance of this new strategy when compared to previously implemented ones, especially when there are greater levels of seating and luggage capacity in an aircraft.

References

Kalic, M.; Markovic, B.; Kuljanin, J. The airline boarding problem: Simulation based approach from different players’ perspective. In Proceedings of the 1st Logistics International Conference, Belgrade, Serbia, 28–30 November 2013; Vidović, M., Kilibarda, M., Zečević, S., Miljuš, M., Radivojević, G., Eds.; pp. 49–54.
Nyquist, D.; McFadden, K. A study of the airline boarding problem. J. Air Transp. Manag. 2008, 14, 197–204.
Soolaki, M.; Mahdavi, I.; Mahdavi-Amiri, N.; Hassanzadeh, R.; Aghajani, A. A new linear programming approach and genetic algorithm for solving airline boarding problem. Appl. Math. Model. 2012, 36, 4060–4072.
Van Landeghem, H.; Beuselinck, A. Reducing passenger boarding time in airplanes: A simulation based approach. Eur. J. Oper. Res. 2002, 142, 294–308.
Jafer, S.; Mi, W. Comparative Study of Aircraft Boarding Strategies Using Cellular Discrete Event Simulation. Aerospace 2017, 4, 57.
Jaehn, F.; Neumann, S. Airplane Boarding. Eur. J. Oper. Res. 2015, 244, 339–359.
Kierzkowski, A.; Kisiel, T. The human factor in the passenger boarding process at the airport. Procedia Eng. 2017, 187, 348–355.
Bidanda, R.; Winakor, J.; Geng, Z.; Vidic, N. A review of optimization models for boarding a commercial airplane. In Proceedings of the 24th International Conference on Production Research, Poznan, Poland, 30 July–3 August 2017; pp. 1–6.
Zeineddine, H. A dynamically optimized aircraft boarding strategy. J. Air Transp. Manag. 2017, 58, 144–151.
Marelli, S.; Mattocks, G.; Merry, R. The Role of Computer Simulation in Reducing Airplane Turn Time. 1998. Available online: https://www.boeing.com/commercial/aeromagazine/aero_01/textonly/t01txt.html (accessed on 26 October 2020).
Delcea, C.; Cotfas, L.-A.; Chirita, N.; Nica, I. A Two-Door Airplane Boarding Approach When Using Apron Buses. Sustainability 2018, 10, 3619.
Cotfas, L.A.; Delcea, C.; Milne, R.J.; Salari, M. Evaluating Classical Airplane Boarding Methods Considering COVID-19 Flying Restrictions. Symmetry 2020, 12, 1087.
Steffen, J.; Hotchkiss, J. Experimental test of airplane boarding methods. J. Air Transp. Manag. 2012, 18, 64–67.
Kisiel, T. Resilience of passenger boarding strategies to priority fares offered by airlines. J. Air Transp. Manag. 2020, 87, 101853.
Qiang, S.-J.; Jia, B.; Xie, D.-F.; Gao, Z.-Y. Reducing airplane boarding time by accounting for passengers’ individual properties: A simulation based on cellular automaton. J. Air Transp. Manag. 2014, 40, 42–47.
Schultz, M. Dynamic change of aircraft seat condition for fast boarding. Transp. Res. Part C Emerg. Technol. 2017, 85, 131–147.
Tang, T.; Wu, Y.H.; Huang, H.; Caccetta, L. An aircraft boarding model accounting for passengers’ individual properties. Transp. Res. Part C Emerg. Technol. 2012, 22, 1–16.
Ren, X.; Xu, X. Experimental analyses of airplane boarding based on interference classification. J. Air Transp. Manag. 2018, 71, 55–63.
Kobbaey, T.; Bilquise, G.; Naqi, A.A. A Comparative Evaluation of Airplane Boarding Strategies with a Novel Method for Sustainable Air Travel. In Proceedings of the 2023 9th International Conference on Information Technology Trends (ITT), Dubai, United Arab Emirates, 24–25 May 2023; IEEE: New York, NY, USA, 2023; pp. 169–174.

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Subjects: Engineering, Aerospace

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Hélio Moreira

Luís Pinto Ferreira

Nuno O. Fernandes

Ana Luísa Ramos

Paulo Ávila

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Update Date: 11 Feb 2024

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1. Introduction

2. Passenger Boarding Strategies

References