Physical workload of flight attendants when pushing and pulling trolleys aboard aircraft

Abstract

The musculoskeletal loads from moving trolleys aboard aircraft were assessed by observation of trolley handling on planes and by physical workload analyses of pushing and pulling of trolleys in a laboratory set up. Trolley handling by a total of 15 female flight attendants was observed on 10 short- and medium-distance flights in different types of aircraft. About 25 selected flight attendants (22 females; 3 males) of five German airlines took part in the laboratory study, which comprised three-dimensional (3D) measurements of posture and hand forces during pushing and pulling of trolleys in a variety of configurations. From the on-flight observations performed, between 150 and 250 trolley movements can be projected for a work shift. The greatest physical workload is to be expected at the beginning of service: The trolleys are fully laden then, and the cabin floor can still be inclined up to 8°, as the aircraft is still climbing, particularly on short-distance flights. The laboratory investigation revealed that the musculoskeletal workload from pushing and pulling depends essentially on the trolley load and on the gradient of the cabin floor. In addition, the degree of stressing depends significantly on the trolley type, mode of handling and personal dexterity. The up/down force component perpendicular to the direction of motion often achieved considerable amplitudes-in some cases equal to or exceeding the force in the direction of movement. The posture analysis demonstrated that pulling forced the flight attendants to adopt ergonomically unfavourable postures such as pronounced flexion of the back, particularly among female subjects. The highest values for flexion of the back occurred while pulling the half-size trolley. The results demonstrate that female flight attendants are likely to overload themselves if they frequently have to move heavily laden trolleys unaided on an inclined cabin floor.

Relevance to industry

On short distance flights, flight attendants have been complaining increasingly of high physical workload from manoeuvring trolleys. On the basis of the presented data airline companies may improve the trolley handling skills of their flight attendances by practical trainings and may ergonomically optimize the general service procedures aboard aircrafts.

Introduction

Passengers aboard aircraft are served with the aid of trolleys. On short- and medium-distance flights, flight attendants have to move what are in some cases heavy trolleys under a tight schedule along narrow and often sloping aisles. In other branches of industry as well, e.g. in transport, the food industry, the retail trade or the nursing service, wheeled containers, trolleys or two-wheeled carts are employed to reduce the proportion of lifting and carrying activities (Jung et al., 2005). These transport aids are mostly pushed or pulled together with their loads. With reference to the literature, “pushing” and “pulling” in the present study are taken to mean the exertion of force with one or both hands in a mainly horizontal plane (Martin and Chaffin, 1972; Hoozemans et al., 1998). Pushing involves a force effect of the hands away from the body, while pulling involves a force effect of the hands towards the body. There is general consensus that hand forces when pulling or pushing do not always have to be precisely horizontal.

Numerous studies have already highlighted the health risks associated with the pushing and pulling of loads (Chaffin, 1987; Hoozemans et al., 1998, Hoozemans et al., 2002; McBeth et al., 2003; Harkness et al., 2003). The risks take the form of overexertion of the musculoskeletal system due to excessive, too long or too frequent force application. At the same time, there are also additional dangers from tripping and slipping when manoeuvring hand-propelled vehicles.

Back pain (backache) is the most frequently cited complaint in the literature (Snook et al., 1978; Hoozemans et al., 1998). Complaints in the shoulder-neck region and in the upper extremities are also attributed to pushing and pulling (van der Beek et al., 1993; Hoozemans et al., 2002).

So far little is known about the degree of musculoskeletal loads and the frequency of musculoskeletal complaints among flight attendants from the moving of trolleys. Winkel (1983) carried out a study with 11 women—not flight attendants—into the handling of full-size trolleys in commercial aircraft. The perceived maximum forces for repetitive exertions were ascertained on a trolley fixed in the laboratory and yielded an average value of 68 N. The maximum force achieved under the same conditions was 270 N on average. No significant difference was found between force exertion for pushing and pulling. On the basis of the minimum force needed to set an 85 kg trolley in motion on carpeting. Winkel (1983) advised not to start serving passengers until 15 or 16 min after take-off, when the gradient of the cabin floor is about 3.5°. He anticipated initial forces of about 100 N, the limit recommended at the time by the Swedish National Board of Occupational Safety and Health.

Because of complaints from female flight attendants about excessive physical workload when handling trolleys on aircraft, the Institution for Statutory Accident Insurance and Prevention in the Vehicle Operating Trades in Germany (BGF) initiated a pilot study to estimate the physical workload from pushing trolleys in preparation for the present study (Kupfer et al., 2000). Using two female flight attendants, the hand forces in the direction of pushing and postures when pushing half-size trolleys were measured in the laboratory. Both the trolley weight (17.9, 43.5, and 70.6 kg) and the floor gradient (0°, 5°, 10°) were varied. The ascertained musculoskeletal loads and the in some cases considerable pushing forces of up to 215 N in particular led to the present study with its far greater scope and complexity. The goal of the study was to determine the musculoskeletal loads on flight attendants when pushing and pulling trolleys under near-authentic conditions. Attempts were made to achieve a real-life assessment of the stress situation from which practical recommendations can be derived for improvements in the service procedure in terms of the handling of trolleys aboard aircraft.

In a research consortium, the service procedures aboard aircraft, the physical strength of flight attendants and their musculoskeletal loads inclusive of lumbar spinal loads were to be investigated in depth. In the part of the study presented here, the emphasis is on the documentation of service procedures aboard aircraft, posture analysis during pushing and pulling, and measurement of the associated hand forces. The other parts of the study will be presented in separate articles in this issue (Schaub et al., 2007; Jäger et al., 2007).