I’d like to first address the low RCS claim, I assume all you proud Brahmos daddies have personally witnessed a test launch of the missile wearing your Sunday best, a smile on your face. I bet your heart swelled with pride as you watched your precious child soaring into the sky leaving a trail of white smoke.
The white smoke or missile plume is “the moving formation of hot exhaust gases (and often also with entrained small particles) outside the rocket nozzle. This gas formation is not uniform in structure, velocity or composition. It contains several different flow regions and supersonic shock waves. It is usually visible as a brilliant flame, emits
intense radiation energy in the infrared, visible and ultra violet segments of the spectrum and is a strong
source of noise”
-page 710, Rocket Propulsion Elements By George P. Sutton, Oscar Biblarz
Now before a proud Brahmos daddy gets upset or embarrassed and claim my Brahmos does not produce a plume, please understands that a plume is perfectly normal and is the expected result of imperfect combustion – all rockets generate a plume while the engine is producing thrust irrespective of the rockets nationality, yes Indian rockets aren’t immune unfortunately - don't believe me? here is photographic evidence from two Indian sources.
It is an established fact that the plume effect increases the radar cross section of all rockets. This has been established by radar observation of countless rocket launches and has been reproduced under laboratory conditions. If you don’t believe me because you think I have an anti-Indian bias then please read the below paper by an Italian (not biased American) researcher on the subject.
The use of the MoM for the RCS
calculation of the missile+plume system has finally led to
the following conclusions:
1) the effect of the plume generally provokes an increase in
the value of the RCS;
2) the resonance effect can be studied accordingly with the
particular system specification."
Plume effect on Radar Cross Section of missiles at HF band
http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA447064
I have every reason to believe that the low RCS claim is false and a competent AWACS crew will detect launch and initiate counter measures.