Evaluation of the Space Shuttle Cockpit Avionics Upgrade (CAU) Displays
In 1999, NASA Johnson Space Center (JSC) initiated a Cockpit Avionics Upgrade (CAU) project to increase shuttle mission safety by improving the crew's situation awareness, reducing their workload, and improving their performance. The primary focus of the project was a complete redesign of the current cockpit displays. To determine the effectiveness of the redesigns, a human-centered evaluation was conducted in the Shuttle Mission Simulator (SMS) at NASA JSC in 2003 and 2004. Measures of crew situation awareness, workload, and nominal and off-nominal task handling performance were made in a series of simulations of off-nominal flight situations during the dynamic flight phases of ascent and entry. The redesigned display formats yielded dramatic increases in situation awareness, reductions in workload, and improvements in performance.
Upgrades to the Caution and Warning System of the Space Shuttle
During a Space Shuttle mission, astronauts are alerted to off-nominal conditions via a Caution and Warning System that often generates a myriad of auditory and visual alerts. A key component of this system is the Fault Summary display, which contains text messages describing the malfunctions. The display often becomes cluttered with extraneous messages, increasing the difficulty of diagnosing a malfunction. In an effort to improve the crew's diagnostic performance, increase their situational awareness and reduce their workload, the Caution and Warning System is being improved as part of the Cockpit Avionics Upgrade. In the first phase of the upgrade, the Fault Summary display is being redesigned with a more logical task-oriented graphical layout and multiple text fields for malfunction messages. In the second phase, the text fields will indicate only the source (i.e., root-cause) of the malfunction to prevent non-operationally useful messages from appearing on the display. These and other aspects of the upgrades are based on extensive collaboration among astronauts, engineers, and human factors scientists. This paper describes the human factors principles applied to upgrading the Caution and Warning System in the presence of inherent limitations associated with legacy manned spaceflight vehicles.
Slotted Waveguide Antenna With Two Radiation Nulls
A design of a linear array antenna having two radiation nulls and otherwise omnidirectional radiation pattern is reported. A new configuration of a waveguide broad wall longitudinal slot doublet with positive and negative offsets with respect to the waveguide center line is used to design the array. This type of doublet produces two radiation nulls. Each of the null directions can be shifted at least up to plusmn25deg by proper choice of slot offset. Resonance and radiation characteristics of the proposed doublet are also presented. Finally, one linear array antenna consisting of seven doublets has been fabricated. Measurements show that the 15 dB null widths are 14.2deg and the null depths are at least 24.8 dB. Maximum gain ripple in the omnidirectional region is 1.75 dB.