by Robert Seagrave, PASS National ATO Safety Respresesntative
Earlier this month, following repairs to the waveguide, a required radiation survey was conducted at the Airport Surveillance Radar in Casper, Wyo. (CPR ASR-8), which is the agency’s Northwest Mountain Region. Test results showed that the maximum permissible exposure (MPE) levels from both Channel A and Channel B exceeded the FAA uncontrolled environment by 84 percent and 24 percent of the standard. The standards for non-ionizing radiation (RF) are discussed in FAA Order 3900.68, “ATO Radiation Safety Program” and in American Conference of Government Industrial Hygienists publications.
The FAA has adopted the MPE levels for uncontrolled environments as the action level for both ionizing and nonionizing radiated energy. For RF, the FAA follows the ANSI/IEEE C95.1 – 2005, “Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz.”
The exposure may have occurred because the protective cover that is required on the Klystron oil tank was NOT in place. Instead, a plexiglass cover was installed on both channels. A PASS member at the site reported that the plexiglass covers were installed one-and-a-half years ago and that same technician also reported that the protective covers were not in use at the facility where he received his on-the-job training. Nor were they in place at the training facility in Oklahoma City.
Any employee working in close proximity or performing maintenance on the system while the radar was operating with cabinet doors open could have been exposed to RF over MPE levels. It was further determined that when the proper metal covers were reinstalled, the RF dropped to acceptable levels. For ASR-8 facilities, the clear plastic viewport in front of the Klystron oil tank was left in permanently. On the viewport itself is the warning “Do Not Leave Permanently Installed.” The plexiglass viewport does not provide any protection against RF. As technicians are often reminded, warnings should be adhered to at all times when working around equipment radiating significant RF energy.
It should be noted that this exposure was discovered during a required radiation survey after the repair to the waveguide. FAA J.O. 3900.68 states:
(1) For the following facilities, surveys must be conducted at least every three years: ARSR, ASR, TDWR, and NXRAD. For all other sources of electromagnetic fields, periodic surveys are only required if there is evidence that employees may be exposed above the applicable MPE. (2) An RF radiation survey is also required at ARSR, ASR, TDWR, and NXRAD facilities within 14 days following major maintenance activities…
Required signage is also defined in the same FAA order.
PASS’s Regional Safety Reps are currently investigating the issue on a site by site basis, thanks to the diligent work of PASS Northwest Mountain Regional Safety Representative, Don Gilbert. Gilbert acted quickly in researching and forwarding the information as soon as it became available. While the issue was discovered in the Western Service Area, PASS has notified the agency about the issue for ASR-8 systems throughout the National Airspace System. In discussion with AJW-23, radiation survey results for all facilities are now kept in a central database. Proper signage requirements have been added to the FY2018 workplace inspection checklist.
When members become aware of potential safety issues, they must notify PASS representatives and appropriate management officials. In addition to local union representatives, PASS has nine regional safety representatives within the Air Traffic Organization (ATO) and a national safety representative to provide assistance to members. If any member is aware that this issue exists at their ASR-8 facility, he or she should immediately contact the local PASS rep and/or the regional safety rep, as well as the appropriate management officials.
