Human Factor

The incident occurred when, during its first flight after a flap change, the aircraft exhibited an undemanded roll to the right on takeoff, a condition which persisted until the aircraft landed back at London Gatwick Airport 37 minutes later. Control of the aircraft required significant left side stick at all times and the flight control system was degraded by the loss of spoiler control. CAUSAL FACTORS: i) During the flap change compliance with the requirements of the Maintenance Manual was not achieved in a number of directly relevant areas: - During the flap removal the spoilers were placed in maintenance mode and moved using an incomplete procedure, specifically the collars and flags were not fitted. - The re-instatement and functional check of the spoilers after flap fitment were not carried out. ii) A rigorously procedural approach to working practices and total compliance with the Maintenance Manual was not enforced by local line management. iii) The purpose of the collars and t...

  The concepts of illumination and luminance are associated with the quantity of light falling on or emanating from a surface, respectively. Illumination is related to the amount of light falling on a surface or an object. Luminance is related to the amount of light coming from an object, such as a video display terminal or a wall.  Luminance is associated with our subjective impression of brightness. The farther you move away from a light source, the more the intensity of illumination. In fact, it decreases as the square of the distance. If you double the distance between an object and a light source, the illuminance measured at the object drops to one-fourth its previous level. sonable range of distances. The reason for this has to do with the way luminance is defined mathematically. Our experience confirms that a wall doesn’t become less bright simply because we move away from it.

 We have an internal biological clock . This clock will run whether subjects are in a cave, in a mine, in a time isolation unit, or whatever. It is not a 24-hour clock; it takes a bit longer.  However, we reset it every day. What makes it reset? The answer is simply that we live in a world which is 24 hours in nature; in which the world revolves around the Sun on a 24-hour basis; a world in which social events have been organized to match the 24-hour day and, in particular, the period of light. In short, man has a biological clock, which we term a circadian clock. This clock approximates the 24-hour day, running just a bit longer, and is adjusted daily by the routine features of life and our environment.  The circadian clock is important. Man, for a variety of reasons, has evolved as a diurnal animal. We are not naturally night time animals. Our cycles affecting such matters as alertness tend to peak during the day. Therefore, common sense and chronobiological theory woul...

 In operating vibrating tools such as impact drills, chippers, pneumatic tools and chain saws, employees frequently complain of hand numbness after the shift. With chronic exposure to these tools employees may develop white finger syndrome or Raynaud's phenomenon. This condition occurs following years of exposure to vibrating tools and will affect blood vessels, nerves, bones, joints, muscles and connective tissues in the hands and arms. The employee can experience a sudden loss of fresh blood supply resulting in a sudden bleaching of the fingers. The hands become particularly sensitive to cold weather, become painful or numb, and it becomes difficult to grip large objects or to have the dexterity to handle small objects. The condition, like so many other things, is dose dependent. That is, the number of times the tools are used and the power spectra or amount of vibration of the tool will determine how long the vibration can be tolerated before the onset of the disorder. The frequ...

  "Work support systems refers principally to a variety of structures used by technicians to gain access to different parts of the airplane.  These structures include the maintenance hangar itself and proceed through scaffolds, ladders, stools, and "cherry pickers."  The underlying purpose of all of these systems is to allow direct access to aircraft components and, hopefully, to make the work easier and safer. Some structures are sophisticated and allow on-the-spot adjustments in height and lateral position. Some major airlines use massive scaffolding systems that move and essentially enclose a large aircraft, thereby allowing direct and safe access to parts such as the vertical stabilizer.  There are problems with existing work support systems. In some instances, a workstand will require a technician to work in an awkward position, thus tending to produce increased fatigue. The cherry pickers have the problem of inherent instability which becomes a safety concern a...