Human factors serves to improve Military Airborne Fire Fighting System

  • Published
  • By Patricia Dunavold and Franz Ravelo
  • 773rd Test Squadron
EDWARDS AIR FORCE BASE, Calif. --  Recently, a team from the 418th Flight Test Squadron and the California Air National Guard from the Channel Islands deployed to Chico, Calif., to evaluate the Military Airborne Fire Fighting System built by the Aero Union Corporation.

This system will be used by the California Air National Guard and the United States Forest Service to fight wild fires here in California.

The overall test objective was to support certification of the MAFFS II system for use on the C-130J-30. The specific human factors objectives were to characterize noise and temperature levels of the cargo compartment environment during operation of the MAFFS II system and to verify that the human-systems interfaces for the MAFFS II were adequate to support airworthiness certification.

Testing of the MAFFS II was conducted in two phases at the Chico Municipal Airport in Chico, Calif., over a two-week period. Phase I was conducted to evaluate the operation and safety-of-flight of MAFFS II on a C-130J-30 aircraft. This phase consisted of loading the MAFFS II onto the aircraft and various ground tests to ensure the system was functioning correctly and was safe to fly.

Phase II consisted of performing retardant drops over a USFS test grid located in Chico, Calif. The grid consists of 100 rows of 20 collection cups uniformly spaces over a cow pasture. The aircraft flies over the grid and drops a load of retardant. Then the cups are quickly collected and weighted to determine the amount of retardant that would actually fall on a fire.

An integrated systems evaluation was also performed during phase II testing as a graduation exercise to demonstrate the MAFFS II capability of the C-130J-30 platform. This evaluation required the pilots of the MAFFS II modified plane to fly along steep ridgelines while following a smaller U.S. Forest Service plane. This emulated the actual fire-fighting procedures that are used by the Forest Service. Smaller planes led the aerial fire-fighting planes into the fire ravaged areas and then provide a visual escape path through the smoke for the larger planes.

During testing, several human factors issues were identified. These issues ranged from simple labeling inaccuracies to potentially dangerous snagging hazards. Human factors engineers used a multitude of techniques to gather data, from simple observation to utilizing complex and expensive equipment. Additionally, the pilots and loadmasters completed questionnaires and provided valuable comments and concerns.

The final human factors evaluation consisted of a combination of both subjective and objective data. One of the most valuable resources for use by human factors engineers are Military Standards. Especially useful is the "Human Factors Bible," Military Standard 1472F, Department of Defense Design Criteria Standard, Human Engineering. This document provides the criteria for everything from the acceptable scale for text to general workspace design.

Some of the tools used for this evaluation were hand-held thermometers and noise level meters. Because of the large size of the MAFFS II equipment, there was a concern that the generators running the equipment would give off too much heat and increase the ambient air temperature in the cargo compartment.

Using a variety of thermometers, including an Omega OS425-LS and two different Omega HHF710s to record the temperature level, readings were taken at several different locations. Single, discrete measurements were taken during ground testing and in-flight, with and without the compressors running and during all the different mission phases.

An additional concern was the level of noise produced by the generators. Using a Bruel and Kjaer 2260 Precision Sound Analyzer, noise level measurements were taken in 30-second increments at more than 18 different locations on the aircraft. Measurements were taken during ground testing and in-flight with and without the compressors running. A baseline level was accomplished on the first day during ground tests with the aircraft on external power.

However, several unexpected problems were discovered. One of the most important was the discovery that, after running for a relatively short period of time, the compressor heads became extremely hot. In fact, with surface temperatures in excess of 150°F and the possibility that a crew member could accidentally touch or fall against one, they were very dangerous.

The simple solution? Place a metal wire guard over the dangerous areas. Other solutions, however, were not so simple.

The awkward shape and lack of feedback of the trigger release mechanism will surely require a re-design.

The evaluation of systems and subsystems not only identifies areas that meet standards and, therefore, alleviates concerns; it can also identify areas that are potentially dangerous to humans. Once potential problems are identified, standard ergonomics principles can be applied, thus making a system like the MAFFS II safer and easier to operate, resulting in less chances of loss of life or property during the fire season. And who wouldn't feel good about a career that allows one to do that?