Value chain · CLM-1291
In plain terms
The 1963 study assumed an aircraft crosses a radar beam in a few seconds at most, too short to wear out its radio parts, though a switched-off radar set could still be damaged by a strong pulse.
The claim as recorded
The FAA's 1963 report RD-64-1 states that "aircraft transiting radio and radar beams are exposed at most for a few seconds", and on that basis judges slow crystal deterioration in crystal-receiver avionics (weather radar, DME, ATC transponder) not a serious problem: at about 200 mW continuous wave such a crystal degrades in about 6 minutes. It states that exposure to 10 mW/cm2 presents no hazard to the lower-frequency avionics (VHF communication, glideslope, ADF, VOR/LOC, marker beacon), whose interference effects are reversible. It flags permanent crystal burnout above about 5 W peak as possible when the set is switched off, and limits for electroexplosive devices as the restrictive case.
Evidence behind this: T3, a government agency report with a named author; the exposure time is stated, not derived or measured in the pages held.
Scope and limits
"A few seconds" is stated for narrow radar and radio beams and is given no calculation in the pages held. A beam kilometres wide would take longer to cross: CLM-1204 gives about 0.5 to 1 minute for the SPS beam. The avionics analysis covers 1963 tube and crystal sets; the report itself (footnote, PDF 8) says solid-state sets "should consider the possible hazard". Its crystal-damage worked example is for pulsed radar peaks, not a continuous power beam. Not tested: the report recommends experimental verification. Partial copy: conclusions and appendices not held.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
PDF 9 [4]: CW power changes the crystal "in approximately 6 minutes"; "Since aircraft transiting radio and radar beams are exposed at most for a few seconds, the deterioration under discussion does not constitute a serious problem"; burnout "when peak powers in excess of 5 watts are applied"; under POWER OFF the T-R tube "will not fire until the incident peak power level has reached 5 to 10 watts". PDF 8 [3]: exposure at the 10 mW/cm2 human limit is found to pose no hazard to the first group of avionics (paraphrased) PDF 6 [1]: purpose, criteria for special-use airspace set aside to protect aircraft near high-power radio and radar transmitters (paraphrased).
Basis: seconds of exposure while transiting a beam; mW/cm2 average power density
Cite this
energyaperture.com/c/clm-1291
CLM-1291, Energy Aperture, as of 1963-12.
Connected records
Other published records linked to this one. A list, not a judgement.