One of the little researched areas during the pandemic is the impact of COVID-19 on aircraft operations and passenger handling during boarding and disembarkation. Dr Michael Schultz, Senior Research Associate at the Chair of Air TransportTechnology and Logistics at the "Friedrich List" Faculty of Transport and Traffic Sciences at TU Dresden, has conducted extensive research on this topic in collaboration with universities and aviation-related institutions in North America and Europe.

Stochastic simulation environment for different operational scenarios

A review article ("COVID-19: Passenger Boarding and Disembarkation", Sep. 2021) summarises the results of one and a half years of research on efficient passenger boarding in the aircraft cabin under pandemic conditions. Here, essential methods were developed and procedures optimised to avoid contacts and COVID-19 infections among passengers. "During normal boarding, there are a considerable number of possible transmission routes when infectious passengers are present," says Dr Schultz. He and the scientists involved used a stochastic simulation environment to analyse and optimise the movement behaviour of passengers and the risk of spread in different operational scenarios. A newly developed mathematical model also takes into account trade-offs between low process times and low contagion risks. In principle, the distribution of seats within the cabin and the associated entry/exit sequences were optimised. The results show that with an improved seat allocation, a reduction of the transmission risk by 90 percent can be expected and at the same time the process times can also be sustainably reduced.

Start 2020 with transmission model and evaluation of commonly used procedures

Another review article describes the step-by-step development of the research work, which started with the development of a transmission model and the evaluation of commonly used procedures in early 2020 (Evaluation of Aircraft Boarding Scenarios Considering Reduced Transmission Risks). Basic modelling considerations of individual minimum clearances and transmission probabilities identified initial suggestions for procedural improvement. For example, specific boarding procedures and the reduction of passenger interactions in the cabin (e.g. by reducing hand luggage) could minimise virus transmission and achieve boarding times of pre-COVID time. However, it became apparent that exiting the cramped cabin in particular is associated with an increased probability of transmission.

Wall Street Journal interview: Less hand luggage = less risk of transmission

In the interview published on this subject in the renowned "Wall Street Journal", Michael Schultz points out that a random boarding order, where passengers are not all seated in the same rows at the same time, would be better to reduce possible transmission. "It would also be important to limit the number of carry-on bags so that a passenger doesn't try to shove something into an overhead compartment while breathing over a seated passenger. A reduction in hand luggage alone, can reduce the risk of transmission by about 75 percent," he is quoted as saying. He also points out that as a precautionary measure, airlines design boarding and deplaning procedures so that passengers walk across the tarmac in the open rather than in poorly ventilated jetways. "Unfortunately, airlines mostly do not opt for the approaches already successfully tested in scientific studies," says Michael Schultz.

Integer linear optimisation problem solved by genetic algorithm

For this reason, the researchers around Dr. Michael Schultz decided to consider additional, realistic assumptions in further investigations. On the one hand, the effects of (self-organising) passenger groups on the optimised seat distribution and the course of boarding were analysed (Analytical approach to solve the problem of aircraft passenger boarding during the coronavirus pandemic), on the other hand, the disembarkation of passengers was in the foreground of the scientific research (Optimised aircraft disembarkation considering COVID-19 regulations). In both cases, taking into account possible transmissions among the different passenger groups, an integer linear optimisation problem was set up and solved by a genetic algorithm. In addition to the existing findings, it was shown that by taking group behaviour into account, both process times (by 40 percent) and transmission risk (by 85 percent) can be minimised. Currently, the results of another research contribution are under review, in which the aspects of hand luggage distribution in the cabin were integrated into the optimisation procedures.

Support by associated research areas

These research results have also made significant contributions to the future ground handling of aircraft (Future aircraft turnaround operations considering post-pandemic requirements). Together with colleagues from the Institute of Logistics and Aviation at TU Dresden and the University of New South Wales, Australia, Dr. Schultz has shown what additional resources are needed to meet pandemic requirements in the future. The result is that, despite optimisation and extended use of resources, ground times will be up to 10 percent longer. This would have a far-reaching impact on the entire air transport network, especially in the case of closely timed flight connections.

Foundations laid for a networked aircraft cabin

Maintaining minimum distances between groups and people has been assumed as a prerequisite in previous scientific studies. However, in reality, the exact determination of the position of passengers within the aircraft cabin is a major technological challenge. In close cooperation with the Chair of Transport Systems Information Technology at the TU Dresden, the requirements from an operational point of view and the possibilities of new technological procedures were compared (Evaluation of Technology-Supported Distance Measuring to Ensure Safe Aircraft Boarding during COVID-19 Pandemic). With this publication, the necessary foundations for a networked aircraft cabin were laid. The radio propagation simulation within a 3D-modelled aircraft cabin as well as the operational processes taking place in the cabin were brought together so that the next research work can be carried out in a holistic modelling environment.