Case Studies in the Achievement of Air Superiority - Air Force ...

AIR SUPERIORITY
USAF EC-121 early warning radar surveillance aircraft in flight over
South Vietnam.
dination with attack formations to mask the approach of U.S. aircraft.
There were two types of jamming: spot jamming, in which a high level of
noise at the bandwidth of the ground tracking radar was beamed back at it,
and barrage jamming, in which the EB-66 sent out pulses across a range of
radar energies in order to confuse several radars, any one of which might
be operating. Spot jamming was employed where and when the frequency
of the ground radar was known; where it was not, barrage jamming was
used. The effect of jamming was to cloud the radarscope of the groundbased
system, thereby covering the radar echoes marking the actual positions
of U.S. planes. With effective jamming, the approach of U.S. strike
formations could be disg~ised.~~ The EB-66s were capable of jamming both
early warning and fire control radars, but the effectiveness of jamming fire
control radars fell off with distance. Unfortunately, the threat of SAMs and
MiG attack kept the unarmed EB-66s beyond the effective range for interfering
with fire control radars, but the jamming planes were still employed
against North Vietnam’s early warning radars, which had relatively great
range.
Because of its focused effect, spot jamming was more effective than
barrage jamming. However, spot jamming depended on accurate intelligence
concerning North Vietnamese radar frequencies. Where that was not
available, the less effective barrage jamming was used. To obtain data on
North Vietnamese early warning radars, EB-66s and even KC-135 tankers
recorded North Vietnamese transmission~.~~ The North Vietnamese
responded to jamming with a variety of countermeasures: overriding the
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