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H igh I ntensity R adio T ransmission A rea Definition: Electro-Magnetic Interference (EMI) produced by high power antennas such as radio and television transmitters and microwave stations. ALL Army aircraft are affected. Effects of EMI.
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High Intensity Radio Transmission Area • Definition: Electro-Magnetic Interference (EMI) produced by high power antennas such as radio and television transmitters and microwave stations. • ALL Army aircraft are affected.
Effects of EMI • Unexplained illumination of segment / warning lights • Unusual instrument readings (Navaid Signals / CIS) • Unexplained flight control movements • Departure from normal flight
Electromagnetic Interference (EMI) and Electromagnetic Variation (EMV) affect certain aircraft more than others. In order to minimize the effects of EMI/EMV, the Department of Defense (DOD) has established a classified list of HIRTA sites, available at S-2 and Flt Ops, which provides locations and standoff distances for those sites.
For high power transmitters not listed in the HIRTA message standard avoidance and standoff distances have been established to aid the aviator in avoiding these sites. The new standard avoidance distances are listed in the current HIRTA message (May 01).
EMI can affect aircraft with Electronic Environmental Effects (E3) hardening installed. • Standoff distances are given for A/C with and without E3 hardening. • If any E3 measures are removed - the standard standoff distance is significantly increased. • Maintaining standoff does not preclude anomalies from occurring.
Frequently affected systems * Transponder * Radar Altimeter * Doppler * Gyromagnetic Compass * ADF * UHF * ICS * Blade De-ice * CIS
All incidents that cannot be confirmed as material or mechanical failure or malfunction through maintenance troubleshooting procedures should be reported as Electromagnetic Interference (EMI)
Symptoms * Deviations in readings * Un-Commanded Control Movements * Disengagement of selected mode * Unexplained Departure From Regular Flight * Unexplained illumination of Caution, Warning, or Advisory lights with/without degradation * Excessive radio noise
Actions on entering HIRTA • Maintain Aircraft Control – Execute the • Appropriate Emergency Procedure • Exit area • Recover system • Notify S-2
AVIATOR’S RESPONSIBILITIES • Ensure incidents concerning HIRTA are reported • Check for HIRTA sites when planning routes in unfamiliar areas • Ensure briefings address information on HIRTA sites • Be familiar with HIRTA Messages