Commercial airline protocol during COVID-19 pandemic: An experience of Thai Airways International.

INTRODUCTION: Coronavirus disease 2019 (COVID-19) pandemic has affected the aviation industry. Existing protocols have relied on scientifically questionable evidence and might not lead to the optimal balance between public health safety and airlines' financial viability.
OBJECTIVE: To explore the implementation feasibility of Thai Airways International protocol from the perspectives of passengers and aircrews.
DESIGN: An online questionnaire survey of passengers and an in-depth interview with aircrews.
SETTING: Two randomly selected repatriation flights operated by Thai Airways International using Boeing 777 aircraft (TG476 from Sydney and TG492 from Auckland to Bangkok). PARTICIPANTS: 377 Thai passengers and 35 aircrews.
RESULTS: The mean age of passengers was 28.14 (95%CI 26.72 to 29.55) years old; 57.03% were female. TG492 passengers were mostly students and significantly younger than that of TG476 (p<0.0001) with comparable flying experience (p = 0.1192). The average body temperature was 36.52 (95%CI 36.48 to 36.55) degrees Celsius. Passengers estimated average physical distances of 1.59 (95%CI 1.48 to 1.70), 1.41 (95%CI 1.29 to 1.53), and 1.26 (95%CI 1.12 to 1.41) meters at check-in, boarding, and in-flight, respectively. Passengers were checked for body temperature during the flight 1.97 (95%CI 1.77 to 2.18) times on average which is significantly more frequent in longer than shorter flight (p<0.0001). Passengers moved around or went to the toilet during the flight 2.00 (95%CI 1.63 to 2.37) and 2.08 (95%CI 1.73 to 2.43) times which are significantly more frequent in longer than shorter flight (p = 0.0186 and 0.0049, respectively). The aircrews were satisfied with the protocol and provided several practical suggestions.
CONCLUSION: The protocol was well received by the passengers and aircrews of the repatriation flights with some suggestions for improvement.

Introduction

Coronavirus disease 2019 (COVID-19) pandemic has affected several industries including aviation. Transmission of the severe acute respiratory syndrome (SARS) associated coronavirus (SARS-CoV) on aircraft was reported—individual with physical proximity to the index symptomatic patient (three rows in front) have approximately three times the risk of the passengers who seated elsewhere [1]. Despite many similarities with SARS-CoV, the novel coronavirus (SARS-CoV-2) appears to transmit more easily than its predecessor. A recent study reported potential transmission from asymptomatic COVID-19 infected individuals [2], suggesting that symptom-based case detection might be no longer adequate [3]. A commercial airline has begun carrying out serology tests on passengers before departure [4] in addition to temperature screening.

Given no specific and robust evidence on the risk of in-flight transmission of the SARS-CoV-2, preventive measures relied on the past experiences; at least 275 options have been proposed to reduce SARS-CoV-2 transmission in five key areas: (1) physical isolation, (2) reducing transmission through contaminated items, (3) enhancing cleaning and hygiene, (4) reducing spread through pets, and (5) restricting disease spread between areas [5].

While several preventive activities have been agreed upon by stakeholders, some measures have raised financial and feasibility concerns to the airline industry. An optimal balance between public health safety and airline financial viability is critical, especially when the airline passenger revenues already dropped by $314 billion in 2020 [6]. General biosecurity measures such as temperature screening of individuals, minimizing inter-personal contacts during the boarding and deplaning processes, limiting movement within the cabin during flight, increasing frequency and quality of cabin cleaning, and simplifying catering procedures [6] have been implemented at the expense of the aviation industry. The International Air Transport Association (IATA) recently endorsed the mandatory face-coverings for passengers and masks for crew members but opposes onboard social distancing because of the significant loss of revenue [6]. IATA asserted that the risk of infectious disease transmission on board is low even without special measures as suggested by scientifically questionable evidence such as contact tracing for selected flights or informal surveys of major airlines [6]. However, proving the effectiveness of these multi-faceted measures have been difficult. Also, these might not be well perceived or complied by some passengers.

Like other national aviation authorities, the Civil Aviation Authority of Thailand (CAAT) has issued a temporary ban on all international flights to Thailand during the COVID-19 pandemic with some exceptions [7]. Several commercial airlines, including Thai Airways International, have been able to operate repatriation flights, organized in coordination with governments to aid citizens stranded abroad. Individuals must fill in and submit the Application for Re-entry Permit to Return into the Kingdom (TM.8) to an immigration officer [8] and the COVID-19 Screening Questionnaire (T.8) to Port Health Officer [9]. The COVID-19 risk score is calculated by using three factors: the number of COVID-19 case in the country of departure, the proportion of seats occupied by the passengers, and flight duration into low, moderate, and high risks (Table 1). Flight without the High-Efficiency Particulate Air (HEPA) filtering system is considered high risk.

Table 1

COVID-19 risk score, The Civil Aviation Authority of Thailand (CAAT).

Score	1	2	3	4	5
Number of Covid-19 Cases in Country of Departure	< 50	50–100	101–500	501–1,000	>1,000
Proportion of Seats Occupied with Passengers (%)	< 40	40–80	> 80	-	-
Flight Duration (hours)	< 4	4–8	> 8	-	-
Risk-based Interventions:
Low Risk (score 3–4)	Passengers: Body temperature check by using a non-contact infrared thermometer before boarding. Passengers with body temperature higher than 37.3 degree Celsius or upper respiratory tract symptoms (cough, sore throat, running nose, and shortness of breath) will be reassessed by Port Health Officer if a boarding pass could be given.
	Crews: Disposable medical or surgical masks.
	Pilots: Disposable medical or surgical masks.
Moderate Risk (score 5–7)	Passengers: Body temperature check by using a non-contact infrared thermometer before boarding and in-flight for long-haul (>4 hours) flights.
	Crews: Disposable medical or surgical masks.
	Pilots: Disposable medical or surgical masks.
High Risk (score 8–11 or no HEPAa filtering system)	Passengers: Body temperature check by using a non-contact infrared thermometer before boarding and in-flight for long-haul (>4 hours) flights.
	Crew: N95 or surgical masks, goggles, and disposable rubber gloves.
	Pilots: Surgical masks and goggles.

aHigh-Efficiency Particulate Air

These repatriation flights offer a wonderful opportunity to gather useful evidence, especially from the passengers’ perspective, for commercial airline protocol development and improvement. This study aimed to explore the implementation feasibility of the Thai Airways International protocol from the perspectives of passengers and aircrews.

Methods

We conducted an online questionnaire survey of passengers and in-depth interview with aircrews of two randomly selected repatriation flights operated by Thai Airways International: TG476 (Sydney-Bangkok; 209 passengers (female 61.24%; adult 92.82%), 3 pilots, and 14 cabin attendants) on April 26 and TG492 (Auckland-Bangkok; 168 passengers (female 51.79%; adult 51.19%), 4 pilots, and 14 cabin attendants) on April 27, 2020. The Boeing 777 equipped with 18 seats in the business class and 306 seats in the economy class were used for both flights (Fig 1).

Fig 1

Passenger seats map of TG476 and TG492 repatriation flights.

Passengers were asked to estimate the distance to the nearest individual(s) at check-in, boarding, and inflight as well as their mobility during the flight. Their opinions and willingness-to-pay for six personal in-flight amenities—disposable food containers, bottled water, gloves, tissue paper, mask, face shield—were assessed using a five-point Likert scale (1, strongly disagree to 5, strongly agree) and an open-ended question, respectively. Passenger’s confidence in the company before and after the trip was assessed by using a ten-point scale (1, lowest to 10, highest).

Descriptive statistics (frequency, mean, and standard deviation) were used for data analysis. The response rate was calculated by using responses from passengers at least 18 years of age. Association between categorical variables was analyzed with the chi-square test. Student’s t-test was used to compare interval data between groups as appropriate. Likert scale findings were presented as mean and standard deviation for simplicity but the comparison between groups was performed by using chi-square or Fisher’s exact test where appropriate.

Ethics committee approval

This study was approved by the Institutional Review Board of Dhurakij Pundit University.

Patient and public involvement

The inception of this study was from the discussion with the pilots and cabin crews of the Thai Airways International. They agreed with the simple anonymous survey of passengers and in-depth interviews with aircrews.

Results

Thirty-seven and forty-one passengers of TG476 and TG492 responded to the survey, respectively. The overall response rate was 22.50% with statistically significant differences between the two flights (18.04% vs 32.56%, respectively; p = 0.007). Mean age and gender distribution of respondents and non-respondents were not statistically different (p = 0.6566 and 0.156, respectively).

The mean age of passengers was 28.14±13.94 years old and 57.03% were female. TG492 passengers were mostly students and significantly younger than that of TG476 (p<0.0001) although both groups have comparable flying experience (p = 0.1192) (Table 2, Fig 1). The average body temperature was 36.52±0.34 degrees Celsius.

Table 2

Characteristics and experience of passengers in two Thai airways repatriation flights.

	Overall	TG476	TG492	p-value
Route		Sydney-Bangkok	Auckland-Bangkok
Flight Distance (kilometers)		7,523	9,566
Flight Duration (hours)		9:25	11:50
Response Rates
- Overall	78/377	37/209	41/168	0.1100
- Age > = 18	63/280	35/194	28/86	0.0070
Agea	28.14±13.94	32.69±13.65	22.53±12.17	<0.0001
Female	57.03%	61.24%	51.79%	0.0650
Student	50.93%	34.93%	70.83%	<0.0001
Flying Experience (times in 2019)a	3.79±6.07	2.64±2.54	4.80±7.89	0.1192
Body Temperature (degree Celsius)a	36.52±0.34	36.61±0.34	36.40±0.30	<0.0001
Physical Distance (meters)a
- Check-in	1.59±0.48	1.57±0.36	1.61±0.58	0.7020
- Boarding	1.41±0.52	1.42±0.28	1.40±0.68	0.8507
- In-flight	1.26±0.65	1.27±0.28	1.26±0.86	0.9239
In-flight Body Temperature Checked (times)a	1.97±0.91	1.32±0.53	2.56±0.78	<0.0001
In-flight Mobility (times)a
- Move Around	2.00±1.65	1.54±1.41	2.41±1.76	0.0186
- To Toilet	2.08±1.54	1.57±1.30	2.54±1.61	0.0049
In-flight Personal Amenitiesa
- Disposable Food Container	4.59±0.78	4.54±0.87	4.63±0.70	0.6000
- Bottled Water	4.77±0.64	4.73±0.77	4.80±0.51	0.6095
- Gloves	4.46±1.02	4.46±1.10	4.46±0.95	0.9864
- Tissue Paper	4.68±0.67	4.65±0.75	4.71±0.60	0.7038
- Mask	4.74±0.69	4.65±0.89	4.83±0.44	0.2523
- Face Shield	4.54±0.88	4.46±1.04	4.61±0.70	0.4540
Willingness-to-Pay for In-flight Personal Amenities (THB)a
- Disposable Food Container	60.63±82.15	48.89±69.95	71.22±91.36	0.2331
- Bottled Water	32.71±65.41	19.05±20.75	45.02±86.72	0.0798
- Gloves	27.42±59.56	14.70±18.53	38.90±78.96	0.0729
- Tissue Paper	21.42±30.00	12.57±13.09	29.41±37.95	0.0123
- Mask	34.04±62.59	24.03±36.40	43.09±78.56	0.1810
- Face Shield	44.04±45.94	29.97±40.67	56.73±47.19	0.0093
Confidence in Thai Airwaysa
- Before	7.64±2.47	7.62±2.49	7.66±2.48
- After	8.10±2.49	8.19±2.46	8.02±2.54
- p-value	0.0001	0.0032	0.0144

aMean±SD; THB, Thai Baht (US$1 = THB32.45 as of April 26, 2020)

Passengers estimated average physical distances of 1.59±0.48, 1.41±0.52, and 1.26±0.65 meters at check-in, boarding, and in-flight, respectively. The physical distances at all stages were not different between the two flights. Passengers were checked for body temperature during the flight 1.97±0.91 times on average which is significantly more frequent in longer than shorter flight (p<0.0001). Likewise, the passengers moved around or went to the toilet during the flight 2.00±1.65 and 2.08±1.54 times which are significantly more frequent in longer than shorter flight (p = 0.0186 and 0.0049, respectively). The passengers agreed with the importance of in-flight personal amenities but were willing to pay for them at varying prices. The confidence in the airline company was statistically significantly increased from 7.64±2.47 before the trip to 8.10±2.49 after the trip (p = 0.0001).

The aircrews were satisfied with the protocol and provided several practical suggestions. Despite the return-to-work intention, they had expressed concerns regarding occupational exposure of themselves and their family members. These concerns seemed to be alleviated after the actual experiences working in the repatriation flights. Physical distancing at approximately 1.5 to 2.0 meters was more practical at the check-in counter, pre-boarding area, and boarding line than during the flight.

The cabin areas were divided by disposable curtains into five designated areas. ‘Clean area’ was located at the frontmost of the plane, in which only crews with PPE were allowed. ‘Buffer zone’ was assigned as a dressing area for crews. In the ‘passenger sitting area’, the initial CAAT requirement to set at least one meter between any two passengers was not feasible for the present seating layout so the repatriation flights asked and received permission from CAAT so that any adjacent seat is empty except for the declared family members. This was also done in the ‘quarantine area’ (the last three rows), which was for either passengers or crews with unanticipated symptoms just identified onboard. In that case, one cabin crew with PPE will be assigned for the service in the quarantine area and could not be close to the other crews within two meters. ‘Lavatories’ at the front of the plane were allowed only for crews. Magazines, newspapers, and unnecessary documents were removed.

Cabin crews got dressed in personal protective equipment (PPE) in the buffer zone with no difficulty. However, they reported several occasions in which the crews with PPE crossed paths with the less protected crews. Passengers received surgical mask and face-shield and cleaned their hands with alcohol gel before boarding; however, this approach was not practical for several passengers who had many carry-ons. Before providing the in-flight services, the cabin crews and passengers had to stay only in the assigned zones and minimize their movements. Prepackaged food in disposable containers, utensils, and bottled water were given to individual passengers. The food service was provided at different times, if possible, to minimize the chance of simultaneous mask removal by nearby passengers. Passengers were asked to use the provided alcohol gel to clean their hands before and after the meal. The passengers were asked to drop the garbage to the garbage cart by themselves or on the service tray to minimize physical contact with the cabin crew. The lavatory was disinfected every use.

During the landing, the cabin crews announced that the passengers remain seated and keep the physical distancing while disembarkation. After landing, the cabin crews noticed several passengers attempted to move out too early which might fail the physical distancing principle, so they decided to allow the passengers to stand and disembark on a row-by-row basis. Aircrews moved to buffer zone and take off the PPE before the cleaning staff moved in for aircraft disinfection. All passengers in both flights tested reverse-transcription—polymerase-chain-reaction (RT-PCR) for COVID-19 and were quarantined at a government-provided hotel in Bangkok for 14 days.

Discussion

The aviation industry has been greatly affected by the COVID-19 pandemic. Several preventive measures have been proposed [5] and some were implemented but might not ensure the optimal balance between public health risk minimization and airline financial viability. While the diagnostics industry has advanced laboratories and healthcare industry has hospital facilities for producing scientifically robust evidence, the aviation industry has a unique and dynamic context that might not be appropriate for evidence generation. The repatriation flights that received permission to operate during the COVID-19 pandemic have provided a partially controlled setting to collect useful data from passengers’ perspective and gather feedbacks from aircrews to assess the implementation feasibility of the mandatory protocol.

The protocol was well received by the passengers and aircrews. Physical distances seemed to be context-sensitive, as suggested by the varying physical distances between the check-in, boarding, and in-flight areas. Estimated physical distance reported by passengers might not be accurate but the data could reflect the subjective perception of passengers which is influential for business.

Some regulations might not have adequate detail so the inputs from the real experiences are essential. For instance, in-flight body temperature check was required for long-haul moderate- and high-risk flights but no frequency was specified. Passengers of the repatriation flights in this study not only agreed with the temperature check but also remained aware that they were approached for a body temperature check.

This study has some limitations. First, the response rates of this voluntary questionnaire survey were low; however, the responses were from an unbiased seat selection and could be representative of the flights. Second, the self-reported data relied on passengers’ perception and might not be accurate to be used as a reference for real practice. Third, the nature of Thai passengers might not be exactly like that of other ethnic origins.

Several preventive measures for in-flight transmission of the SARS-CoV-2 has relied on past experiences and raised financial and feasibility concerns to the airline industry.

Evidence on the implementation feasibility of commercial airline infection control protocol, especially from the perspectives of passengers and aircrews, has been lacking.

Our study suggests that the passengers reported varying degrees of physical distancing at check-in, boarding, and in-flight and that the in-flight body temperature check was possible.

The Thai Airways protocol was well received by the passengers and aircrews.

(DTA)

Click here for additional data file.

16 Jul 2020

PONE-D-20-15480

Commercial Airline Protocol during COVID-19 Pandemic: An Experience of Thai Airways International

PLOS ONE

Dear Dr. Pongpirul,

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Reviewer #1: 1.This article by Krit Pongpirul gives a research article on commercial airline protocol during COVID-19 pandemic from Thai airways international to explore the implementation feasibility of airways protocol. They conducted an online questionnaire survey of passengers and in-depth interview with aircrews of two flights and they thought that the protocol was well received by the passengers and aircrews of the repatriation flights. Overall, this article gives a broad interview of the potential flight-level prevent and control transmission of SARS-CoV-2 in flght, but lacks depth.

2.The satisfaction of passengers and crew members should not be taken as the main evaluation parameters of the study. The number of research flights should be increased to improve the reliability of the data.

3. 124-125 “The overall response rate of this research was 22.50.” and “Passengers estimated average physical distances” were the results bias?

4. The prolonged flight time is bound to increase the number of temperature tests and the number of activities of passengers on the plane, including eating, going to the toilet, etc. If there are confirmed patients on the flight but they are not detected before boarding the aircraft and subject them to the necessary isolation and treatment, these activities must increase the risk of normal passenger infection.

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17 Jul 2020

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Response: The data has been deidentified and deposited in the UK Data Service. The data was also uploaded to the manuscript submission system while the DOI link is not yet available.

Editor: 3. Thank you for including your competing interests statement; "The authors have declared that no competing interests exist." We note that one or more of the authors are employed by a commercial company: Thai Airways International Public Company Limited. Please provide an amended Funding Statement declaring this commercial affiliation, as well as a statement regarding the Role of Funders in your study. If the funding organization did not play a role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript and only provided financial support in the form of authors' salaries and/or research materials, please review your statements relating to the author contributions, and ensure you have specifically and accurately indicated the role(s) that these authors had in your study. You can update author roles in the Author Contributions section of the online submission form. Please also include the following statement within your amended Funding Statement. “The funder provided support in the form of salaries for authors [insert relevant initials], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.” If your commercial affiliation did play a role in your study, please state and explain this role within your updated Funding Statement. Please also provide an updated Competing Interests Statement declaring this commercial affiliation along with any other relevant declarations relating to employment, consultancy, patents, products in development, or marketed products, etc. Within your Competing Interests Statement, please confirm that this commercial affiliation does not alter your adherence to all PLOS ONE policies on sharing data and materials by including the following statement: "This does not alter our adherence to PLOS ONE policies on sharing data and materials.” (as detailed online in our guide for authors http://journals.plos.org/plosone/s/competing-interests). If this adherence statement is not accurate and there are restrictions on sharing of data and/or materials, please state these. Please note that we cannot proceed with consideration of your article until this information has been declared. Please include both an updated Funding Statement and Competing Interests Statement in your cover letter. We will change the online submission form on your behalf. Please know it is PLOS ONE policy for corresponding authors to declare, on behalf of all authors, all potential competing interests for the purposes of transparency. PLOS defines a competing interest as anything that interferes with, or could reasonably be perceived as interfering with, the full and objective presentation, peer review, editorial decision-making, or publication of research or non-research articles submitted to one of the journals. Competing interests can be financial or non-financial, professional, or personal. Competing interests can arise in relationship to an organization or another person. Please follow this link to our website for more details on competing interests: http://journals.plos.org/plosone/s/competing-interests

Response: The Funding Statement was updated as “Thai Airways International provided support in the form of salaries for author ST, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of the authors are articulated in the ‘author contributions’ section.” The Competing Interests Stement was updated as “The authors declare that they have no conflicts of interest. The commercial airline affiliation of author ST does not alter our adherence to PLOS ONE policies on sharing data and materials.”

Reviewer #1: 1.This article by Krit Pongpirul gives a research article on commercial airline protocol during COVID-19 pandemic from Thai airways international to explore the implementation feasibility of airways protocol. They conducted an online questionnaire survey of passengers and in-depth interview with aircrews of two flights and they thought that the protocol was well received by the passengers and aircrews of the repatriation flights. Overall, this article gives a broad interview of the potential flight-level prevent and control transmission of SARS-CoV-2 in flght, but lacks depth.

Response: Thank you very much for the comments. Although we wish we could conduct a more in-depth study, there had been several situational limitations that prevented us from doing so. We decided to conduct the study as best as possible.

Reviewer #1: 2.The satisfaction of passengers and crew members should not be taken as the main evaluation parameters of the study. The number of research flights should be increased to improve the reliability of the data.

Response: The ‘satisfaction’ of passengers and crew members was not the primary focus of our study. Rather, they were ask to report useful information from their perspectives as shown in Table 2. We wish we could increased the number of research flights as advised.

Reviewer #1: 3. 124-125 “The overall response rate of this research was 22.50.” and “Passengers estimated average physical distances” were the results bias?

Response: Despite the low response rate, given the situational limitations mentioned above, we believe that the selection bias was only a minor concern in our study. As mentioned in the Discussion section, the responses were from an unbiased seat selection so the findings could be representative of the flights.

Reviewer #1: 4. The prolonged flight time is bound to increase the number of temperature tests and the number of activities of passengers on the plane, including eating, going to the toilet, etc. If there are confirmed patients on the flight but they are not detected before boarding the aircraft and subject them to the necessary isolation and treatment, these activities must increase the risk of normal passenger infection.

Response: Thank you very much. We agree with the point raised but our data could not be used for testing the hypothesis.

27 Jul 2020

Commercial airline protocol during COVID-19 pandemic: An experience of Thai Airways International

PONE-D-20-15480R1

Dear Dr. Pongpirul,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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29 Jul 2020

PONE-D-20-15480R1

Commercial airline protocol during COVID-19 pandemic: An experience of Thai Airways International

Dear Dr. Pongpirul:

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