Loading upon cabin attendants induced by the pushing and pulling of trolleys on board airlines

Status:

completed 01/2004

Aims:

On-board service tasks are now increasingly also performed during the ascent and descent phases of short flights. Stewards and stewardesses complain of the increased physical load experienced whilst the trolleys are being pushed and pulled. An initial study (Project 4094 "Recording of the musculo-skeletal load experienced by stewardesses when pushing trolleys on board aircraft") by BIA and the BGF (the institution for statutory accident insurance and prevention in the vehicle operating trades) has already been conducted under practical conditions for specification of a permissible maximum pushing force. The study measured the loading experienced by two stewardesses under variation of the relevant service conditions. In order for the results of the study to be generalized, the results of the load analysis were now to be validated statistically by means of a larger subject collective, and the analysis extended to include the task of pulling the trolleys. New findings for the assessment of such pushing and pulling tasks were also included in the study. In order for the requirements of such a follow-on project to be met, the BGF, BIA, IfaDo (Dortmund) and IAD (Darmstadt) entered into co-operation.

Activities/Methods:

The anthropometric data of approximately 500 airline stewards and stewardesses and their physical ability, in terms of a maximum force test, were recorded by Darmstadt Polytechnic. The anthropometric data of as many stewards and stewardesses from the airlines involved as possible were also evaluated. This measurement produced the fifteenth force percentile (215 N) of this random sample, which in turn constitutes the basis for the assessment procedure based upon EN 1005-3 Annex B. The recommendations are divided into action-independent values for long-haul flights with a low frequency of action, and action-dependent values for short-haul flights with a higher frequency of action, against the bottleneck of physical performance.

The pulling and pushing tasks associated with various types of trolleys were simulated on a special laboratory apparatus (airline floor with variable inclination). The body posture, external forces (hand forces and floor reaction forces) and spinal loading (compression force on disk L5/S1) were determined on twenty-five selected cabin attendants (stewardesses and a maximum of three stewards) by means of a combined kinematic and dynamic analysis.

For assessment of the musculoskeletal load, 1,200 tests were performed in which 25 air cabin attendants were required to pull and push trolleys under a range of conditions on an adjustable inclined plane. The CUELA system was employed for three-dimensional recording of body posture and movement, and three-component force sensors developed by the BIA were used to measure the applied forces and points of action of the hands. In total, some 3,600 pushing and pulling processes were recorded and evaluated. The body posture (such as bending and torsional moments) and applied force data (compressive and shear forces) were processed through a software interface, developed by the BIA, to the CUELA system, thereby permitting automated further processing by means of the "Dortmunder" biomechanical model for measurement of spinal loading in the Institute of Occupational Physiology at the University of Dortmund (IfADo). The data recorded by the BIA also serve as a basis for the application of national and international ergonomic procedures.

Results:

The results of the study demonstrate that the handling of trolleys may involve high musculoskeletal stress, particularly when full trolleys must be propelled at frequent intervals on an inclined surface, as is generally the case on short-haul flights. The stress is reflected in ergonomically unfavourable body postures, high applied forces of the hands, and high spinal stress. Owing to its high tendency to tip, the half-size trolley requires comparatively high handling forces combined with unfavourable body posture. These forces are particularly evident when trolleys must be pulled.

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