The radiosonde data from weather balloons was obtained by Tom Kaye from NOAA via a friend. This data was handed over to R99. I then handed over data related to the placard--area, weight, rigidity--to R99.
Applying science and math, R99 proved that the placard would drift approximately nine miles to the northeast after separation from 305. Therefore, given that we know where the placard was found it was simply a matter of reverse engineering and determining where the jet was when it separated--coincidentally it put 305 on the Western Flight Path. Sad but true for them there FBI Flight Pathers.