After the aircraft had thoT~ughly mixed the opposing air
currents by flying repeatedly through the interface as it searched
for the targets, the ground radar returns would gradually fade away.
This corresponds to \~hat was actually observed.
In summary, without the data to make a more definitive evaluation
of this case, the most likely cause seems to be a combined radio-optical
mirage as described above. If so, this is another eXCI1l1ple of a natural
phenomenon so rare that it is seldom observed: for a 0.25° critical
mirage angle, the temperature contrast required is on the order of
10" or 15°C in the space of ahout 1 em.
Washing~on, D.C. (see Appendix L ) 19-20 and 26-27 JUly 1952.
Weather: mcstly clear, a few scattered clouds, v1sibility
10 to IS mi., temperature 76° to 87° F, dewpoint 61° to 72 0
F, surface
winds from SE, light, near surface, from 300 0 to 320 0 aloft, light.
Radio refractive index profiles are shown in Figs. 13,1.4, and 15, in
Md., at an e levat ion of 88 Ill. (289 ft.) above sea level. T11ere are
a tremendo·J.s number of reports of UFOf: observed on these two nights.
In most i~stances visual ohservcTs, especially in scrambled aLrcraft,
were unable to see Largets indicated all ground radar, or to make air-
borne radar contact. Ground radar observers were often able to find
a return in the general arca of reported visual contacts. especially
':' the case of ground visual reports where only an azi muth was given.
A few c-xcerpts fron~ typi ca 1 reports Juring these j nddents arc g).ven
bela....· :
Control towor operator, Andl'cws AFB" 0100 to nS(l() EST, ZO July
1952:
An airman hccamc exritcd during the con-
versation and suddenly yelled "there goes one."
I Sa\~ a fallinr, star go from ovcrhcaL! a short
distance ~~ol1th anJ b,l"rn out. AbL)ut two minutes
later (the airma'·.~ said, 1l'I11crct~ ;mothcr one;
227
After the aircraft had thor1ughly mixed the opposing air
currents by flying repeatedly through the interface as it searched
for the targets, the ground radar returns would gradually fade away.
This corresponds to I~hat was actually observed.
In stUnmary, without the data to make a more definitive evaluation
of this case, the most likely cause seems to be a combined radio-optical
mirage as described above. If so, this is another example of a natural
phenomenon so rare that it is seldom observed: for 11 f).25° critical
mirage angle, the temperature contrast required is on the order of
10" or 15°C in the space of ahout 1 cm.
Washingt_on, D.C. (3ee Appendix L ) 19-20 and 26-27 July 1952.
Weather: mcstly clear, a few scattered clouds, vlsihility
10 to 15 mi., temperature 76 0 to 87° F, dewpoint 61° to 72° F, surface
winds from SE, light, near surface, from ~noo to 320 0 aloft, light.
Radio refractive indf'x profiles are shown in Figs. 13, 1.4, and 15, .in
Md., at an elevation of 88 111. (289 ft.) ahove sea level. 'Mlere Bre
a tremendo·.ls number of reports of UFO!' observed on these two nights.
In most i~stances visual observers, especially in scrambled a.rcraft,
wert! unable to see Largets indicated Qil ground radar, or to make air~
borne- radar contact. Ground radar ob;;ervl'l'S were oftcn able to find
a rt'turn in the general arCH of reported vi sual contacts I especially
~:' the case of ground visual reports whcrc only an azimuth was given.
A few excerpts fron~ typi\.~a 1 report::; Juril1l~ these j nddents arc gi yen
below:
1!l52:
Control tower operator, !\ndl'cws J\FB" 0100 to OSO() EST, 20 July
An airman hccamc exrited during the con-
vers a ti ('11 and 5udderl1y ye lled "there WW5 one."
r sa" a fallinr. star go from ovcrllcau a short
distancp ~'Ollth an.! h,l"rn out. Ahout two minutes
later (the airmd'·.; said, "'I11erc'!l 8110thcr one;
227