Masters Theses

Date of Award

5-2004

Degree Type

Thesis

Degree Name

Master of Science

Major

Aviation Systems

Major Professor

Richard Ranaudo

Abstract

The purpose of this thesis is to examine the pilot vehicle interface of the GBU-38, 500-pound Joint Direct Attack Munition integration with the B-2A weapon system operated by the United States Air Force with respect to controls and displays from a human factors perspective. This thesis highlights the basic problems associated with software intensive, glass cockpit displays in a modern combat aircraft using the GBU-38/B-2A integration as a case study and gives the conclusions and solutions our test team reached.

An abbreviated background of the basic workings and displays associated with weapons control and delivery is given at first with an emphasis on the weapons inventory and top-level target file formats on the data entry panel, and the multipurpose display unit weapon and bay-level pages. Volumes could, and are, written about how to fully operate the displays associated with weapons control, and only enough information is given to allow the reader to understand the problems discussed in this thesis.

Next, methods and conditions are discussed on data collection to obtain the results. Display adequacy surveys were prepared based on the Air Force Flight Test Center’s adequacy rating scale and the pilot’s workload was evaluated using the Bedford 10-point workload scale. 669 individual responses were collected over a seven-month period from April 2003 to October 2003. All five adequacy of display evaluation areas were rated satisfactory with ratings in the mid 90% range. The workload adequacy evaluation area was rated marginal, 60% due to the number of button pushes and time required to complete desired mean point of impact updates. Improvements to decrease the high workload are discussed.

The status of the weapons and weapon control displays are discussed next. Specific improvements, such as a two row numbering system for guided stores on the smart bomb rack assembly and a new blocked store symbol, both decrease the workload by the pilot in employing large numbers of guided weapons. Also, the addition of a small tick mark on the weapon coffin symbol on the bay-level weapons display reduces the pilot scan time for discovering degraded weapons and increases pilot situational awareness. The lack of timing cues for software loading is also discussed, as is the poor internal timing capability and absolute measurement ability of humans.

Finally, the major findings are summarized with supporting examples from the GBu-38 program. These findings accentuate the need to simplify the modern combat cockpit, decrease the processing time of the machine as much as possible and allow the machine to take over house keeping chores since the human operator could already be task saturated. All designed to allow the human to make mission critical decisions the machine cannot make.

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