Experimental Study on Individual and Group Evacuation of Passengers from an Aircraft Cabin in the Pitch/Roll State
Yunhe Tong
Round 1
Reviewer 1 Report
The study presents and investigates pedestrian dynamics in an aircraft simulator, which is an interesting approach. However, there are a few key concerns that need to be addressed:
1 It would be beneficial to clarify the differences between pedestrian dynamics in inclined environments such as ships or roads. Conducting similar experiments in different platforms with similar characteristics might not provide valuable insights into pedestrian behaviour.
2 The paper lacks essential details regarding the experimental design, particularly the instructions provided to the participants.
3 The sample size in this work appears to be low, which raises concerns about the statistical robustness of the conclusions drawn.
4 Given that pedestrian movements are influenced by factors such as height, it is important to address whether these factors were adequately considered in the study.
Author Response
Thank you very much for your suggestions. each of which has benefited me greatly, and I will answer these points in turn below.
Point 1: It would be beneficial to clarify the differences between pedestrian dynamics in inclined environments such as ships or roads. Conducting similar experiments in different platforms with similar characteristics might not provide valuable insights into pedestrian behaviour.
Response 1: A description of the particularities of aircraft evacuation was added, particularly regarding comparing inclined aircraft with floating ships and inclined roads, which can be seen on lines 80 to 90. On the one hand, the aircraft space is narrow inside, and the structure is complicated. Passengers likely receive the impact of seat legs and other equipment in the inclined aircraft cabin, which was emphasized in FAA experiments, with new reference[32]. On the other hand, compared with other scenarios, the aircraft evacuation time is very short, which makes passengers likely to choose a running method with a faster evacuation, such as the phenomenon observed in the A380 aircraft's emergency evacuation demonstration experiment. as observed in the A380's Emergency Evacuation Demonstration Experiment (at 1:18, https://www.youtube.com/watch?v=XIaovi1JWyY). In previous experiments, however, experimental subjects were required to move or evacuate in a walking mode, which limited the speed range. In this work, passengers are required to evacuate as quickly as possible to simulate the real evacuation process. The experimental results in this work confirmed that the pitch/roll angle has different effects on the larger speed.
Point 2: The paper lacks essential details regarding the experimental design, particularly the instructions provided to the participants.
Response 2: A description of the experimental design was added, which can be seen on lines 131 to 138. During the course of the experiment, we first measured the physiological parameters of the passengers, asked him/her to wear experiment specific clothing, and informed him/her about the safety of the experiment. Then the passenger would then be asked to sit in a position and wait for instructions, which were divided into normal walking and rapid evacuation. Normal walking meaning walking comfortably and naturally. Rapid evacuation meaning evacuate at the fastest speed. After the cabin simulator will tilt to a pitch/roll angle, the experimental commander issues the command. Passenger moved to the forward exit of the cabin in the commanded movement mode, completed one test, and returned to their seats, waiting for the cabin simulator to change angle and begin the next experiment. In the individual movement experiment, there are two modes, in the cabin, to obtain the individual's base speed and maximum speed, respectively. In the group evacuation experiment, only the rapid evacuation mode existed to simulate the evacuation of a real group in an aircraft cabin.
Point 3: The sample size in this work appears to be low, which raises concerns about the statistical robustness of the conclusions drawn.
Response 3: In this work, each experiment condition is performed twice, which was not noted in previous versions and is now supplemented on line 149. The main focus of this work is to analyze the effects of different experimental conditions on the same individual or group movements. Therefore, the method of repeating experiments multiple times under different experimental conditions of the same subject is adopted instead of a large number of subjects participating in different experiments. The number of participants in both individual and group experiments was designed according to previous similar studies, and statistical analysis of variance was added to the new manuscript to prove the reliability of the data.
Point 4: Given that pedestrian movements are influenced by factors such as height, it is important to address whether these factors were adequately considered in the study.
Response 4: I'm sorry, I didn't quite understand whether 'height' refers to the height of the passenger or the height of the aircraft cabin. Information about the height of the passengers has been added to the new version. The main goal of this article is to analyze the effect of different pitch/roll angles on individual speed and group evacuation, so there is no analysis of individual speed at different heights. I can add to this in the next revision if you think it is needed. For cabin height, although the cabin is in a higher position, the cabin simulator in the experiment is closed, and the passenger does not need to evacuate to the outside, only to reach the exit. So passengers are not affected by being at a higher altitude.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript by Zhang and co-workers addresses an important question of passenger evacuation times based on the cabin at various pitch or bank angles. Most often such evacuation times are based on a cabin at 0o pitch/bank. The experiments are well designed and make use of a to scale aircraft cabin simulator on a hydraulic platform. Unfortunately, I have several major concerns which need to be addressed. These are below.
MAJOR CONCERNS.
1) The English is extremely poor and in some cases it was unclear as to the point being made/concluded by the authors. I would thoroughly recommend that the manuscript be proof-read by an individual well versed in aviation and whose first language is English. A few examples of such deficiencies are below (English Deficiencies).
2) Regarding the Methods, no mention is made of passenger size/weight. This is a particularly important point considering the level of obesity in in Western industrialized countries in particular. The authors should make the point that future studies should be undertaken to address this issue.
3) In several figures (e.g. Figs 7, 9, 12A, 13A) the authors show the effect of pitch and roll orientations on passenger exit speed and state that increases or decreases are evident for this parameter. However no statistical testing is undertaken to determine if such changes are significant and indeed the large error bars might suggest otherwise. I would recommend that ANOVA tests be used to determine if the various degree pitch/roll attitudes do in fact significantly change from a level attitude.
4) I am not sure what the authors were undertaking in the sections “Distance” and “Time headways” and there is no corresponding description in the Methods. The authors should explain.
5) Lastly, the authors should comment on the practical application of their findings. After all, in a crash-landing there is little control over the final attitude of the aircraft when it comes to rest.
OTHER COMMENTS.
1) Comparison of the current findings to prior work (e.g. Fig 8) is more appropriate to the Discussion rather than the Results. In fact earlier work could just be verbalized in the Discussion and it is not necessary to graph previously published work by other investigators.
English Deficiencies.
1) the term “trim” angle can be easily confused with pitch. The authors should replace the former term with “bank” or “roll” angle as used in some parts of the paper.
2) line 29 “Canada launched a fire and 23 passengers lost their lives are surrendering” means what??
3) line 35. …”emergency landing due to the failure of the resumed flight” meaning is unclear?
4) line 44- replace “posture” with “attitude”
5) line 52- replace “exercise” with “movement.”
6) line 59. What does passenger’s “biological diversity” mean? Gender, weight, height?
7) line 64- landing rack presumably means “landing gear” or “undercarriage”
8) line 118, presumably “pedestrian object” refers to a passenger? Please clarify.
9) line 172- what do the authors mean by “discrepancy in physical quality considering the gender..”
10) line 247- I assume the authors mean “exit” door rather than “export” door.
11) line 266- “size of the front predecessor speed” means what?
12) line 346- “pedestrian’s athletes” means what?
Comments for author File: 
Comments.pdf
Very poor. Needs to be proof-read by an aviation specialist who is English -proficient
Author Response
Response to Reviewer 2 Comments
Thank you very much for your suggestions. each of which has benefited me greatly, and I will answer these points in turn below.
Point 1: The English is extremely poor and in some cases it was unclear as to the point being made/concluded by the authors. I would thoroughly recommend that the manuscript be proof-read by an individual well versed in aviation and whose first language is English. A few examples of such deficiencies are below (English Deficiencies).
Response 1: I apologize for my English writing and thank you for your correction. I have corrected each of the writing errors you mentioned and other similar errors in this article. In addition, I used MDPI's editing services to embellish the language of the article, and the related proofs are shown in the diagram.
Point 2: Regarding the Methods, no mention is made of passenger size/weight. This is a particularly important point considering the level of obesity in in Western industrialized countries in particular. The authors should make the point that future studies should be undertaken to address this issue.
Response 2: The height and weight information for participating passengers was supplemented on lines 138 and 144. At the end of the article, it is also mentioned that obesity may influence the experiment results and that future studies will consider the effects of obesity factors on passenger movement and evacuation in the aircraft cabin, on lines 416 to 420.
Point 3: In several figures (e.g. Figs 7, 9, 12A, 13A) the authors show the effect of pitch and roll orientations on passenger exit speed and state that increases or decreases are evident for this parameter. However no statistical testing is undertaken to determine if such changes are significant and indeed the large error bars might suggest otherwise. I would recommend that ANOVA tests be used to determine if the various degree pitch/roll attitudes do in fact significantly change from a level attitude.
Response 3: The results of the ANOVA method analysis for individual movement speed, group evacuation time, line density, forward distance, and forward time at different pitch/roll angles are supplemented. As for individual movement speeds, since the experiment was designed to be carried out by the same individual at different conditions, one-way repeated measures ANOVA was used for calculation, with the results shown in Table 3 and rows 212 through 215. The parameters of the group evacuation experiment were analyzed by one-way ANOVA, with the results as rows 263 to 265, 306 to 308, 331 to 332, and 356 to 358. The results are consistent with the original conclusions.
Point 4: I am not sure what the authors were undertaking in the sections “Distance” and “Time headways” and there is no corresponding description in the Methods. The authors should explain.
Response 4: Added explanation for distance and time headway analysis, lines 326 through 366. In the previous section, we found that pitch/roll angles can affect group evacuation efficiency, where in addition to having a direct effect on the individual speed, there is another effect on group evacuation (as the value of average speed reduction in the group evacuation is not within the range of the individual speed reduction). So this article would like to explore what factors pitch/roll angles also affect. Based on previous studies of group movement, the most likely factors that affect individual speed are density and distance headway (distance from the passenger in front). So I extracted the density and distance headway corresponding to each passenger in a group evacuation in the aisle area (similar to the environment studied by others) and analyzed that the pitch/roll angle had no significant effect on the density and distance headway. I think the effect of pitch/roll angle on individual speed is still doped, and I want to strip the speed parameters off. According to formula 6, the distance headway can be expressed as the product of forward personnel speed and time headway. The time headway is statistically analyzed, and it is found that the pitch/roll angle has a significant effect on the time headway. Therefore, it is concluded that during the group evacuation of an aircraft cabin, the pitch/roll angle attenuates the individual speed and increases the headway between passengers, which in turn reduces the evacuation efficiency.
Point 5: Lastly, the authors should comment on the practical application of their findings. After all, in a crash-landing there is little control over the final attitude of the aircraft when it comes to rest.
Response 5: Practical applications are supplemented in the conclusion section of the article, in lines 415 to 427. Although the pitch/roll angle cannot be controlled during a forced landing, the effect of the pitch/roll angle on the aircraft cabin evacuation efficiency should be considered. In aircraft evacuation, particularly in a fire accident, where reduced evacuation efficiency can result in additional casualties, inclined cabins should be considered in aircraft cabin safety design and emergency evacuation airworthiness requirements. In addition, current research on aircraft cabin evacuation is dominated by numerical simulation, with most of the available data being macro data ( evacuation time, evacuation flow rate) or micro pedestrian dynamics data in other scenarios, lacking pedestrian dynamics data in real aircraft cabin environments. The data in this work can provide greater support for cabin evacuation numerical simulation, including experimental data and predictive models.
OTHER COMMENTS.
Other point 1: Comparison of the current findings to prior work (e.g. Fig 8) is more appropriate to the Discussion rather than the Results. In fact earlier work could just be verbalized in the Discussion and it is not necessary to graph previously published work by other investigators.
Other response 1: Figure 8 was changed, removing other studies' data. The differences between this article's results and other studies verbalized in the discussion were added on lines 230 to 250.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
All my concerns have been addressed.
Author Response
Thank you very much for your comments and suggestions, which have benefited me greatly.
Reviewer 2 Report
Only remaining issue is point # 4 which was not addressed. Thus please define distance headway as "distance from the passenger in front"
Author Response
Thank you very much for your comments and suggestions, which have benefited me greatly.
I have revised the article to your opinion, mostly the text and diagram about "distance from the passenger in front", in 323-346 lines, 370-393 lines, and Figure 14.
