1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. Declaration of Interests
  8. References


In 2010, malaria caused approximately 216 million infections in people and 655,000 deaths. In the United States, imported malaria cases occur every year, primarily in returning travelers and immigrants from endemic countries. In 2010, five Plasmodium falciparum malaria cases occurred among crew members of one US commercial airline company (Airline A). This investigation aimed to assess the malaria prevention knowledge, attitudes, and practices (KAP) of Airline A crew members to provide information for potential interventions.


The web link to a self-administered on-line survey was distributed by internal company communications to Airline A pilots and flight attendants (FA) eligible for international travel. The survey collected demographic information as well as occupation, work history, and malaria prevention education.


Of approximately 7,000 nonrandomly selected crew members, 220 FA and 217 pilots completed the survey (6%). Respondents correctly identified antimalarial medication (91% FA, 95% pilots) and insect repellents (96% FA, 96% pilots) as effective preventive measures. While in malaria-intense destinations, few FA and less than half of pilots always took antimalarial medication (4% FA, 40% pilots) yet many often spent greater than 30 minutes outdoors after sundown (71% FA, 66% pilots). Less than half in both groups always used insect repellents (46% FA, 47% pilots). Many respondents were unaware of how to get antimalarial medications (52% FA, 30% pilots) and were concerned about their side effects (61% FA, 31% pilots).


Overall, FA and pilots demonstrated good knowledge of malaria prevention, but many performed risky activities while practicing only some recommended malaria preventive measures. Malaria prevention education should focus on advance notification if traveling to a malaria-endemic area, how to easily obtain antimalarial medications, and the importance of practicing all recommended preventive measures.

Malaria is a major public health problem worldwide, with approximately 216 million infected people and 655,000 deaths in 2010, mostly affecting developing countries.[1] In the United States, despite recommendations from health agencies, such as the Centers for Disease Control and Prevention (CDC), a steady number of imported malaria cases occur each year, typically from returning travelers and immigrants from malaria-endemic areas.

Many US commercial airlines travel regularly to malaria-endemic countries. Data on malaria cases among US airline crew members are scarce; however, previous studies in other countries suggest a low occupational risk for airline crew members traveling to malaria-endemic areas.[2, 3] Long layovers in areas endemic with Plasmodium spp. can increase the risk of malarial infection.[1, 4]

In 2010, five Plasmodium falciparum malaria cases occurred in the United States among airline crew members of one large commercial airline company (Airline A).[5] All five had a recent history of travel to West Africa where, within areas of intense transmission of malaria, exposure for even short periods of time can result in infection. Four of the five cases were reported within a 4-day period: three by the Florida Department of Health and one by the Pennsylvania Department of Health. This cluster of malaria cases among crew members raised concern of a potential outbreak and of insufficient preventive practices utilized by Airline A crew members. The CDC-recommended preventive measures in malaria-endemic countries include taking appropriate antimalarial medication; wearing protective clothing when outdoors, especially from dusk to dawn; minimizing contact with mosquitoes by remaining in well-screened or air-conditioned locations; using insecticide-treated mosquito nets or applying a permethrin-containing insecticide to clothing; and using an effective mosquito repellent, such as N,N-diethylmetatoluamide (DEET), applied to the exposed parts of the skin.[6]

Airline A's malaria prevention education program, incorporating the CDC's guidelines, included information about malarial transmission, its signs and symptoms, and how to prevent illness. It also provided instruction on what to do if one developed fever. In recent years, malaria prevention education, developed by the airline's occupational and health services (OHS) staff and with CDC consultation, occurred during initial and recurrent employee training, as well as through other venues, such as the company employee websites, posters, and wallet cards which list malaria symptoms, what to do if any occur, and OHS contact information. The airline recommended that crew members keep a 26-day supply of atovaquone-proguanil (A/P, Malarone, GlaxoSmithKline) at home when working “on-call” for travel. Employee purchases of Malarone were 100% reimbursed. For short notice travel, antimalarial prophylaxis was also offered through a telephonic screening and prescription process. The airline's general practices also included securing hotels that met minimum criteria for health, safety, and malaria prevention, as applicable, eg, private rooms with air conditioning.

The aim of this investigation was to assess the malaria prevention knowledge, attitudes, and practices (KAP) of Airline A crew members when traveling to a “malaria-intense destination,” defined by Airline A in their training as a destination in which a person can potentially become infected with malaria during short layovers. As there appeared to be a comprehensive occupational malaria prevention program in place, the goal was to determine knowledge gaps, inappropriate attitudes, or incorrect practices among Airline A crew members that may be contributing to the recent increase in malaria infections so that appropriate interventions could be developed.


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. Declaration of Interests
  8. References

A KAP survey was developed by CDC, with the assistance of the Florida Department of Health and the Airline A OHS office, and determined to be exempt from review by the CDC Institutional Review Board. The 36-question KAP survey was self-administered anonymously through an online survey tool and took 15–20 minutes to complete. A CDC letter about the KAP survey, containing the survey webpage link, was disseminated by Airline A through numerous internal communication channels including company electronic newsletters, OHS web pages, e-mails to flight attendants (FA), and through pilot union communications. Survey participation was voluntary and respondents could skip any questions. Information collected included demographics, occupation, work history, malaria training history, and preferred training methods. Participants who indicated they had worked internationally at least once during the previous year were asked additional questions about their KAP in a “malaria-intense destination.” The survey did not collect personal identifying information or respondents' Internet Protocol (IP) addresses to maintain anonymity.

The investigation population consisted of approximately 12,000 Airline A crew members (∼50:50 pilots to FA) who are eligible to travel internationally. Of these, approximately 7,000 received direct communication about the survey: all pilots received an e-mail from the pilot union and a non-random sample of 1,061 FA, whose travel did include West Africa in the previous year, were sent an individual e-mail from Airline A. Despite attempts to extend the e-mail communication to the remaining FA, it was not accomplished. Descriptive and variable frequency analysis was conducted as one group and by occupation, using SAS 9.2 (SAS Institute Inc., Cary, NC). Airline A was not involved in the data collection or analysis, but received the aggregate results.


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. Declaration of Interests
  8. References

The survey analysis consisted of 220 FA and 217 pilots, a 6% participation rate (Table 1). The majority of FA and pilot participants were 45 years old or older (>59% for both groups), had worked for the airline 10 or more years (81 and 86%, respectively), and almost all had traveled internationally for work (99 and 94%). FA were 20% male; pilots were 96% male. Most participants reported knowing ahead of time that they would have a layover in a malaria-intense destination (78 and 86%). Among FA who worked an on-call schedule (n = 125), 62% reported receiving <4 hours' notice for flights; among pilots (n = 111), 80% had more than 8 hours' notice for flights. Less than one third of FA and pilots believed they were at high risk for malaria because of their jobs.

Table 1. Flight attendant (FA) and pilot respondent characteristics and perception of malaria risk*
 FA (%) n = 220Pilot (%) n = 217
  • *

    Response rate was not 100% for all questions.

Male44 (20.0)209 (96.3)
Female175 (79.5)8 (3.7)
Age group
≤24 y1 (0.5)0 (0.0)
25–34 y25 (11.4)4 (1.9)
35–44 y64 (29.1)24 (11.1)
45–54 y74 (33.6)123 (56.9)
≥55 y56 (25.5)65 (30.1)
Typical advance notice for international travel if worked “on-call”
Never on-call77 (38.1)87 (43.9)
<4 h78 (38.6)21 (10.6)
4–8 h31 (15.3)18 (9.1)
9–24 h15 (7.4)59 (29.8)
1–2 d0 (0.0)12 (6.1)
≥3 d1 (0.5)1 (0.5)
Length of employment at Airline A
<5 y36 (16.6)27 (12.6)
6–10 y6 (2.8)3 (1.4)
≥10 y175 (80.6)185 (86.0)
Frequency traveled international for work in past year
Never2 (1.0)12 (5.7)
1–10 times36 (17.4)37 (17.5)
11–20 times33 (15.9)37 (17.5)
21–40 times44 (21.3)63 (29.9)
>40 times92 (44.4)62 (29.4)
Knew had layover in malaria-intense destination before international travel
Yes159 (77.9)172 (86.0)
No45 (22.1)28 (14.0)
Reported risk of getting malaria because of job
None0 (0.0)7 (3.3)
Little34 (16.0)68 (32.2)
Moderate110 (51.6)84 (39.8)
High66 (31.0)46 (21.8)
Do not know3 (1.4)6 (2.8)

Almost all participants were aware that malaria could be fatal and was transmitted by mosquitoes (Table 2). They also correctly identified DEET, long pants and sleeves, minimizing time outdoors, and use of antimalarial medications as effective prevention methods. Twenty-eight percent of FA incorrectly selected “avoid the local drinking water” as a malaria prevention measure.

Table 2. Flight attendant (FA) and pilot respondent answer frequencies for malaria knowledge questions*
 FA (%) n = 220Pilot (%) n = 217
  • DEET = diethylmetatoluamide.

  • *

    Response rate was not 100% for all questions.

Can malaria be fatal?
Yes213 (100.0)211 (99.5)
No0 (0.0)1 (0.5)
How is malaria transmitted? (choose only one answer)
By touching infected people0 (0.0)0 (0.0)
Through contaminated water0 (0.0)0 (0.0)
By mosquitoes214 (100.0)212 (100.0)
Through cough and sneezing0 (0.0)0 (0.0)
Through dog bites0 (0.0)0 (0.0)
Select the methods that prevent malaria (check all that apply)
Wearing DEET210 (95.5)208 (95.9)
Wearing long pants and sleeves205 (93.2)207 (95.4)
Minimizing time outside204 (92.7)207 (95.4)
Taking antimalarial medication199 (90.5)206 (94.9)
Staying in air-conditioned rooms155 (70.5)184 (84.8)
Avoid drinking the local water (incorrect)62 (28.2)19 (8.8)
Select insect repellents effective against mosquitoes (check all that apply)
DEET205 (93.2)211 (97.2)
Citronella oil46 (20.9)23 (10.6)
SkinSoSoft® with IR353547 (21.4)13 (6.0)
Lemon eucalyptus22 (10.0)6 (2.8)
SkinSoSoft® bath oil (incorrect)38 (17.3)10 (4.6)
Ultrasonic devices (incorrect)27 (12.3)3 (1.4)
Mega-vitamin B doses (incorrect)13 (5.9)6 (2.8)

Attitudes and practices regarding insect repellents and antimalarial medication use were also assessed (Table 3). More than 90% of FA and pilots believed that insect repellents protect against malaria; however, less than half (46 and 47%, respectively) always wore insect repellent on their skin when at a malaria-intense destination. Seventeen percent of FA and 15% of pilots indicated they avoid repellents because of the chemicals or smell. Most believed that antimalarial medications would protect them from malaria (76 and 89%), but 61% of FA and 31% of pilots were concerned about the medications' side effects.

Table 3. Flight attendant (FA) and pilot respondent frequencies in attitudes and practices toward insect repellent and antimalarial medication while at a malaria-intense destination*
 FA (%) n = 220Pilot (%) n = 217
  • *

    Response rate was not 100% for all questions.

Insect repellents
Wear on skin while outdoors
Never10 (5.0)14 (8.1)
Rarely15 (7.5)7 (4.0)
Sometimes33 (16.4)20 (11.6)
Most times51 (25.4)50 (28.9)
Always92 (45.8)82 (47.4)
Wear on clothes while outdoors
Never57 (29.1)58 (33.3)
Rarely33 (16.8)27 (15.5)
Sometimes31 (15.8)29 (16.7)
Most times30 (15.3)25 (14.4)
Always45 (23.0)35 (20.1)
Antimalarial medications
Rate how easy it is to get antimalarial medication through Airline A
Very easy12 (5.9)26 (12.6)
Somewhat easy33 (16.1)47 (22.8)
Neither easy nor hard61 (29.8)60 (29.1)
Hard34 (16.6)39 (18.9)
Very hard23 (11.2)20 (9.7)
Medication not available42 (20.5)14 (6.8)
Have enough advance notice to pick up
Yes103 (52.8)91 (51.4)
No92 (47.2)86 (48.6)
Take to prevent illness
Never146 (72.6)58 (33.3)
Rarely24 (11.9)19 (10.9)
Sometimes19 (9.5)10 (5.7)
Most times4 (2.0)17 (9.8)
Always8 (4.0)70 (40.2)

When asked about the ease of obtaining antimalarial medications through their airline, approximately 28% from both occupations reported it was “hard” or “very hard” to obtain and 21% of FA and 7% of pilots indicated that it was not available. A large proportion of FA and pilots reported not knowing how to get antimalarial medications (52 and 30%, respectively), not having enough notice to obtain them prior to travel (47 and 49%), not understanding when antimalarial medications should be used (30 and 16%), and being confused as to how to take antimalarial medications (31 and 19%). In addition, 33% of FA and 13% of pilots believed antimalarial medications were too expensive. The majority of FA (73%) and 33% of pilots reported that they never took antimalarial medications.

While at malaria-intense destinations, almost all pilots (99%) and FA (98%) reported always sleeping in the company's contracted hotel with the air conditioning running in their rooms (86 and 84%). Additionally, the majority indicated they wore long pants and sleeves, at least some of the time, and most spent time outdoors or in open air locations in and outside the hotel to eat, exercise, or visit local attractions (Table 4).

Table 4. Flight attendant (FA) and pilot respondent frequencies in practices and activities while at a malaria-intense destination*
 FA (%) n = 220Pilot (%) n = 217
  • *

    Response rate was not 100% for all questions.

Wear long pants
Never16 (7.9)5 (2.8)
Rarely21 (10.3)7 (3.9)
Sometimes52 (25.6)27 (15.2)
Most times61 (30.0)60 (33.7)
Always53 (26.1)79 (44.4)
Wear long sleeves
Never17 (8.4)9 (5.1)
Rarely34 (16.8)29 (16.3)
Sometimes66 (32.7)50 (28.1)
Most times54 (26.7)52 (29.2)
Always31 (15.3)38 (21.3)
Spend greater than 30 min in open-air hotel areas after sundown
Never19 (9.3)27 (15.2)
Rarely40 (19.6)33 (18.5)
Sometimes86 (42.2)77 (43.3)
Most times33 (16.2)30 (16.9)
Always26 (12.7)11 (6.2)
Eat outdoors after sundown
Never32 (16.0)38 (22.1)
Rarely44 (22.0)40 (23.3)
Sometimes94 (47.0)72 (41.9)
Most times24 (12.0)18 (10.5)
Always6 (3.0)4 (2.3)
Exercise outdoors at dawn or dusk
Never125 (62.5)102 (59.6)
Rarely46 (23.0)32 (18.7)
Sometimes21 (10.5)27 (15.8)
Most times8 (4.0)8 (4.7)
Always0 (0.0)2 (1.2)
Visit outdoor city areas
Never20 (10.1)44 (25.9)
Rarely28 (14.1)28 (16.5)
Sometimes71 (35.9)64 (37.6)
Most times50 (25.3)30 (17.6)
Always29 (14.6)4 (2.4)
Visit outdoor rural areas
Never66 (33.2)74 (43.0)
Rarely53 (26.6)48 (27.9)
Sometimes68 (34.2)39 (22.7)
Most times9 (4.5)11 (6.4)
Always3 (1.5)0 (0.0)

Pertaining to Airline A's malaria prevention education program, FA most frequently rated the program as fair (32%) and pilots as good (37%; Table 5). The most common methods participants reported to have received malaria prevention education were through casual conversation, periodic communications from the airline, and the malaria wallet card. When asked to select the single most common source of health information before traveling, both occupations reported “WHO/CDC/state health department websites” first, followed by “word of mouth” for FA and “not sought” for pilots. The most frequent malaria prevention education methods rated as “very good” or “good” by FA and pilots were the Malaria Frequently Asked Questions (FAQ) sheets in the airport lounges, the Health Services webpage, articles or briefings from fellow crewmembers who had been infected with malaria, and the malaria wallet card. The top preference for a pre-travel reminder among both occupations was a pop-up message on the “trip awarded/placed on work schedule” webpage.

Table 5. Flight attendant (FA) and pilot respondent rating frequencies of Airline A's malaria prevention training, and preferred information sources, training, and reminder methods*
 FA (%) n = 220Pilot (%) n = 217
  • *

    Response rate was not 100% for all questions.

Overall rating of malaria prevention education and training
Very good7 (3.3)19 (9.7)
Good33 (15.5)72 (36.9)
Fair68 (31.9)54 (27.7)
Poor56 (26.3)36 (18.5)
Very poor42 (19.7)29 (14.9)
No training available7 (3.3)4 (2.1)
Top 5 methods have received malaria prevention education and training through Airline A
Casual conversation128 (58.2)155 (71.4)
Periodic communication84 (38.2)124 (57.1)
Airline A malaria wallet card87 (39.5)111 (51.2)
Airline A FA or pilot webpage56 (25.5)92 (42.4)
Computer-based training29 (13.2)90 (41.5)
Top 5 responses on most common source of travel health information before traveling
WHO/CDC/state health departments56 (26.5)48 (22.5)
Not sought before traveling19 (9.0)44 (20.7)
Airline A FA or pilot webpage20 (9.5)40 (18.8)
Word of mouth35 (16.6)13 (6.1)
Airline A health services webpage26 (12.3)12 (5.6)
Rating on top 5 methods to receive malaria prevention education and training
Airline A Frequently Asked Questions sheet  
Very good61 (33.7)24 (12.6)
Good41 (22.7)50 (26.3)
Fair33 (18.2)51 (26.8)
Poor16 (8.8)32 (16.8)
Very poor30 (16.6)33 (17.4)
Airline A Health Services webpage
Very good34 (19.5)26 (13.9)
Good56 (32.2)43 (23.0)
Fair45 (25.9)55 (29.4)
Poor18 (10.3)31 (16.6)
Very poor21 (12.1)32 (17.1)
Article or briefing from crew member who had malaria
Very good51 (28.5)65 (34.4)
Good40 (22.3)46 (24.3)
Fair29 (16.2)28 (14.8)
Poor23 (12.8)14 (7.4)
Very poor36 (20.1)36 (19.0)
Airline A malaria wallet card
Very good33 (18.0)37 (18.7)
Good53 (29.0)62 (31.3)
Fair44 (24.0)62 (31.3)
Poor31 (16.9)18 (9.1)
Very poor22 (12.0)19 (9.6)
Malaria poster in airport lounges
Very good54 (30.2)20 (10.6)
Good37 (20.7)44 (23.4)
Fair39 (21.8)56 (29.8)
Poor17 (9.5)33 (17.6)
Very poor32 (17.9)35 (18.6)
Rating on reminder methods before travel to a malaria-intense destination about malaria prevention
Pop-up on Airline A work scheduling webpage
Very good77 (41.4)88 (45.4)
Good33 (17.7)61 (31.4)
Fair29 (15.6)22 (11.3)
Poor11 (5.9)11 (5.7)
Very poor36 (19.4)12 (6.2)
E-mail message 2–3 d prior to travel
Very good51 (28.3)57 (30.2)
Good35 (19.4)56 (29.6)
Fair25 (13.9)29 (15.3)
Poor19 (10.6)23 (12.2)
Very poor50 (27.8)24 (12.7)
Text message 2–3 d prior to travel
Very good39 (21.5)52 (27.5)
Good32 (17.7)53 (28.0)
Fair24 (13.3)24 (12.7)
Poor25 (13.8)28 (14.8)
Very poor61 (33.7)32 (16.9)


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. Declaration of Interests
  8. References

Numerous studies have assessed the KAP among international travelers toward malaria and its prevention; however, ours was one of the few to assess malaria and prevention KAP among commercial airline crew members who travel internationally, often to malaria-intense destinations.[2, 7-15] Owing to their frequent travel for durations ranging from one to several days, this unique population has an occupational risk for malaria and needs to understand those risks while remaining vigilant in practicing appropriate preventive measures.

This survey consisted primarily of two distinct occupational populations: FA, the majority of whom had traveled to West Africa in the previous year, and pilots eligible for international travel. The gender difference within the two respondent groups was likely due to the gender distribution within the occupations. Overall, participants demonstrated excellent awareness about the basics of malaria transmission and preventive measures. However, some incorrectly reported “avoid drinking the local water” to prevent malaria, which indicates that additional education on malaria is still warranted. Many respondents reported a low perception of their occupational risk for malaria, especially disturbing among the FA as the majority had made at least one trip in the previous year to West Africa.[6] Despite the confidence in insect repellents and the small number with concerns about DEET and its odor, less than half in each group indicated they always used insect repellent. On the basis of this, crew members should also be educated about effective topical insect repellents other than DEET and the practice of wearing long pants and sleeves, preferably treated with permethrin, for protection when at malaria-intense destinations.

The single greatest need identified in this survey was better access to and understanding of antimalarial medications, as based on the high proportion of pilots and FA that never used the antimalarial medication for prevention. Despite Airline A's program for telephone access to Malarone prescriptions, with 100% reimbursement, most participants perceived that antimalarial medications were difficult to obtain, too expensive, or not available. Additionally, many indicated that they were confused about how to take the medications, concerned about side effects, or believed antimalarial medications would not protect them. These attitudes may partially explain why so few participants reported taking antimalarial medication when traveling to a malaria-intense destination. The malaria prevention program should include a simple and streamlined process to obtain antimalarial medications, the requirement to keep a supply of antimalarial medication at home for anyone working on-call with potentially <8 hours notice of travel to a malaria-intense destination, and education on the use of the medications and their side effects.

Although following all preventive measures cannot guarantee someone will not become infected with malaria, the risk could be reduced through a comprehensive and mandatory malaria prevention education program. This program should reinforce good preventive practices (eg, sleeping in company-contracted hotels with air conditioning), and provide further education about destinations, timeframes, and activities that pose a higher risk for exposure. Two of the most frequent sources of malaria education reported during this investigation were “word of mouth” and “casual conversation.” These methods can be beneficial if a trusted person was passing along correct information, but detrimental if the information or advice from a trusted person was incorrect. In order to ensure crew members receive correct and consistent information, education should be provided in an appropriate learning environment, which may be different between pilots and FA. Additionally, there should be ample opportunities to ask questions from a knowledgeable health care professional.

Both occupational groups reported a strong preference to hear about the experiences of fellow crew members who were recently ill with malaria. This practice should be pursued with a crew member trained to serve in this role and assist in raising crew members' awareness of their occupational risk for malaria. Training can be re-emphasized with educational material in airport lounges, such as posters and the FAQ sheets. As scheduling work trips can occur months in advance, sending text and e-mail messages 2 to 3 days prior to travel to a malaria-intense destination would remind crew members to prepare their preventive measures before departure.

This investigation was subject to at least five limitations. The low participation rate, which was not unexpected for an Internet survey, makes generalizability to all crew members difficult. Selection bias was introduced as FA whose travel included West Africa in the previous year were actively solicited by a company e-mail to participate in the survey. Their responses may be different from other FA eligible for international travel. Also, selection bias by the participants may have occurred, as those who completed the survey may have been different from nonparticipants. The assessment of malaria knowledge may have been biased if participants sought assistance while completing the questions. Finally, reporting bias could be present, as participants may under or over report the frequencies of their practices knowing that their employer would receive the cumulative information, participants were free to skip questions, and without personal identification information or IP addresses, there was no control to avoid duplicate questionnaire submissions from the same participant.

Despite a sound basic knowledge of malaria transmission and preventive measures, both the FA and pilot populations had a low perception of their occupational risks for malaria. Many participants practiced risky, but some unavoidable, activities that may have increased their malaria exposure and rarely used all the recommended preventive measures during layovers at malaria-intense destinations. Minimum goals for a mandatory malaria prevention education program for international airline crew members would be to (1) know in advance if they are traveling to a malaria-intense or malaria-endemic destination; (2) be able to quickly and easily obtain antimalarial medications before travel; (3) remain aware of and use all available malaria-preventive measures; and although not addressed in this KAP survey, (4) be aware of the signs and symptoms of malaria; and (5) know how and where to access care immediately if they become ill. Lastly, to measure any improvements in FA and pilot KAP after the airline makes changes to their malaria prevention education program, a follow-up survey would be recommended.


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. Declaration of Interests
  8. References

The authors thank the contributions of Dr Richard Hopkins, Florida Department of Health; Dr Noelle Molinari, CDC; Sandy Taylor, RN, Airline A; and the Airline A leadership and personnel who supported the survey and assisted with survey communications.

Declaration of Interests

  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. Declaration of Interests
  8. References

P. K. states that her employer (Emory University, Atlanta, Georgia, USA) receives a fee for her consultation at Airline A. All other authors state that they have no conflicts of interest.


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. Declaration of Interests
  8. References