Ehhh...
Russians are seriously underestimating the Stealth capability of the West.
That's to put it mildly.
Cause if we'll take a directional diagram of P-18 in elevation plane...
...we would discover that even if F-117 was in the noticeable gap at 16 degrees (distance of 23-25 km and altitude of 6-7 km give us an area between 13 and 17 degrees), but to get there it had to cross the lower 'lobe' with peak at 14 degrees undetected, and was detected 23-25 km away, its meter-wave RCS has to be no more than 0,002 square meters!
P. S.: Even if we assume that it was actually detected by the noticeable lobe at 12-14 degrees, this means that it had to avoid detection by the main lobe between 5 and 9 degrees. An object with RCS of 0,002 m^2 would have been detected between 40 and 50 km by the main lobe, which probably means that actual RCS is even smaller.
