June 26, 2020, ©. Leeham News: In our Corner series about flying during the COVID-19 pandemic, we look closer at the boarding and deboarding part.
We have identified it as possibly the most troublesome part of a flight during the COVID pandemic. We look at the findings from simulations by boarding/deboarding experts.
When one looks at the whole chain of events for a commercial flight and combines it with recent research into the primary virus contamination process (via the exhaled breath of an infectious person), the boarding and deboarding processes have the most unpredictable and troublesome face to face moments.
A report from an experienced boarding simulation team is in final review and will publish in the coming days. The report is produced by Dr. Michael Schultz, Institute of Logistics and Aviation, Dresden University of Technology, and Dr. Jörg Fuchte, Diehl Aviation.
There is considerable knowledge around simulations of airliner boarding and deboarding. Target has then been how different schemes (random, least row first, etc.) affect the efficiency of the process.
Now the target is minimizing the instances and time passengers spend in close proximity, waiting for bags to be put in bins and passengers to find their place.
By adding a virus transmission model to well-known boarding and deboarding simulation tools, the chance of a contagious person infecting others can be simulated.
The report analyzes different boarding strategies, with each strategy simulated 125,000 times to cover individually different behaviors, passengers entering the aircraft at slightly different times, or changes in the entry sequence.
The result is a statistically relevant analysis of the number of critical contacts caused by different boarding strategies.
Figure 2 shows a results table from the report. The avg. row shows the average number of additional possible infections followed by RSD, which stands for Relative Standard Deviation (a measure of the amount of variation of the result in correlation to the average value).
The conclusions from the simulations are:
“The standard random boarding without additional distances and normal carry-on luggage results in about 5-6 critical contacts between passengers.
Changing the boarding procedure reduces the number of contacts by more than half. Introducing a distancing of 1.6 m reduces the number of critical contacts for the random boarding to about 1-2. Hence, distancing alone does not eliminate these contacts.
Carry-on luggage influences the time spent in the aisle at a high physical workload (with high breathing). Reducing the luggage by 50% reduces the number of critical contacts to about 1 for the random boarding.
Boarding procedures like outside-in or reverse pyramid have a profound effect and reduce the number of critical contacts substantially below 1, even with normal carry-on luggage.
In the context of COVID-19, the question arises, how these contacts will be critical in terms of transmission probability. The authors derived a transmission risk model and evaluated the individual passenger contacts. Here, they find that back to front procedures will provide less transmission risk than random boarding but at the costs of higher boarding times.
The use of the rear door will reduce the transmission probability significantly for all boarding strategies.
The transmission probability during deboarding is hard to influence since physical distancing is difficult, if not impossible, to impose. The number of contacts and the transmission probability remain at a high level, which indicates deboarding as the critical process in the aircraft cabin.
To reduce the transmission probability, the timing of passengers entering the deboarding would need to be controlled.”
Airlines should focus their COVID-19 work on the boarding and deboarding procedures. Stowing of hand luggage is a major cause of critical contacts. Reduction schemes like letting it be stowed in the cargo bay in exchange for a perk shall be a focus.
In addition, boarding schemes like outside-in are effective.
The most critical moment is deboarding, where passengers are standing face to face in the aisle for a long time, waiting for the aisle to clear for deboarding, Figure 1. A scheme where passengers remain seated until the rows ahead move would help a lot.
There is presently no initiatives around deboarding to our knowledge. It would be an area where the airlines could achieve significant improvement in lowering infection risks.
My friend Mentourpilot has flown as a passenger the trip Barcelona-Frankfurt-Stockholm with his family on Lufthansa in the week. He gives a good view of flying in Europe just days after the partial opening: