I've bought the same antenna, and I've got worse results than my home made Cantenna...
When I purchased Flightaware antenna, it worked worst than my Cantenna. I finally discovered that this was due to strong RF noise (TV, FM, Cell/Mobile signals). The RF noise is very high in my area as I live in an urban high rise buildings area.
Adding a filter to Flightaware antenna grately improved it's performance, and it started performing much better than Cantenna.
To check RF noise in your area, please see following How-to, particularly
OPTION-1 and
OPTION-4Do I Need A Filter? .
.