Anomalous Echoes Captured by a B-52 Airborne Radarscope Camera

3. Frame-by-Frame Description of Radarscope Photographs

• Frame 771 - The clock is set to Zulu time or GMT, and shows 0906 and 14 seconds (0406:14 local time, CDT). The sweep has completed approximately half of its first revolution and the 3 inner range rings are clearly visible in the central altitude-hole area, one at 0.75 NM, another at 1.25 NM and a third, brighter, ring at 1.75 NM. This area appears largely free of the speckling which increases later in the sequence. The edge of the surrounding bright area of ground return is sharply delineated at about 2.1 NM. A small discrete echo appears at azimuth 138 degrees, ahead and a few degrees to the right of the nose of the B-52 and just inside the third range ring, its nearer edge measured at 1.62 NM slant range (Note 2). This echo appears slightly elliptical with its major axis lying obliquely aslant the range axis.
• Frame 772 - 3 seconds later, at 0906 and 17 seconds, no echo is visible at the previous location but a similar discrete echo, distinctly elliptical and with its major axis similarly oblique, appears at 242 degrees, 1.05 NM, aft of the right wing.
• Frame 773 - 0906 and 20 seconds. Now the previous echo has decayed and a new echo, somewhat brighter and larger, but still very discrete, appears at 40 degrees azimuth, 1.05 NM off the left wing. The echo is also elliptical, this time its major axis oriented approximately on the PPI range axis. It also appears to be accompanied by, indeed conjoined with, a much smaller and fainter but still discrete secondary echo at slightly greater range (~ 1.15 miles) on roughly the same azimuth. (A very small and indistinct echo possibly also appears at about 138 degrees, range about 1.05 miles.) Picture resolution and/or contrast is deteriorating slightly. The inner 3/4-mile range ring is now virtually undiscernable.
• Frame 774 - 0906 and 23 seconds. There is no clear target echo on this scan. Background speckle inside the altitude hole is increasing.
• Frame 775 - 0906 and 26 seconds. The noise speckling is very evident on this scan and both the first and second range rings are virtually invisible. Again there is no definite target echo, but a possible return is visible cutting the 1.75 NM ring at ~350 degs. The unique brightness of this feature (Fig.2), brighter than the brightest ground return on frame 775, may be due to a strong echo (perhaps augmented by the underlying range marker amplitude). Density contours measured by Claude Poher show characteristics that appear inconsistent with a radar noise artefact or print emulsion defect. It remains possible but not probable that it is a slightly blurred photo artefact introduced at print-projection stage.


Fig. 2. Detail of suspect "echo" from frame #775. The original image (right) can be rendered at extreme contrast as a roughly oval "blip" (left). A noise artefact amplified by a fluctuation in the noisy 1.75 NM range ring (center) seems unlikely in view of the photometry. A photographic artefact remains a possibility.

• Frame 776 - 0906 and 29 seconds. An echo has now reappeared at the same azimuth and the same range as the double echo on frame 773, 40 degrees at 1.05 nautical miles. It covers the same radial extent as the double echo on frame 773, though it is less bright and not distinctly divided in two parts. (A pair of echoes can arguably be identified amid the speckles at about 1.5 miles range aft of the right wing, but they are only marginally above the noise level and may not be significant.)
• Frame 777 - 0906 and 32 seconds. There is again an echo at the same 40 degree bearing and slightly closer at 1.0 NM. This is a single compact echo, brighter again with no visible secondary echo and with only a small ellipticity. As in 773 and 776, the major axis of the ellipse is alligned approximately radially. (There is another possible echo aft of the right wing, a radial smudge sitting athwart the 1.75-mile range ring at 246 degrees. Possibly this is a close pair on the same azimuth. But again the noise level near the scope periphery means that the status of this echo is marginal.)
• Frame 778 - 0906 and 35 seconds. Another single compact echo at 40 degrees and 1.0 mile, again slightly elliptical, almost identical to 777.
• Frame 779 - 0906 and 38 seconds. Now there is a double echo again, still at 40 degrees, with two slightly less distinct and less bright components, of similar appearance, connected by a suggestion of a faint "bridge", at about 0.9 and 1.1 miles on the same radius.
• Frame 780 - 0906 and 41 seconds. Again a single bright, compact, elliptical echo, similar in appearance to 777 and 778, still at 40 degrees but now at about 0.95 mile.
• Frame 781 - 0906 and 44 seconds. An echo (or pair of echoes) somewhat similar in appearance and range to 779, but now at 39 degrees azimuth.
• Frame 782 - 0906 and 47/48 seconds. Still at 39 degrees, but now closer at about 0.87 NM, is a single, bright, compact and almost circular echo.
• Frame 783 - 0906 and 50/51 seconds. There are no unidentified point echoes visible during this scan. The altitude-hole area now appears free of noise and all three range rings and the heading marker are again distinct. The sharp edge of the surrounding ground return is by now closer, having moved steadily inward from about 2.15 NM slant range in 771 to about 1.8 NM in 783.

4. Radar Specifications and Mode of Operation ››