Originally Posted by
gophish11
The data for W563 shows they were slowly climbing through 29,100 at the time, and we were level at 30,000.
Still, this does verify that we were indeed less than 1,000 ft. vertical
FL300 and FL291 is not a loss of separation, particularly when you're looking at data from a 3rd party. There is some allowable error in altitude reporting and even the (required) autopilot altitude hold is not perfect. Even if they are indicating FL300 and FL291 on the controller's scope, that meets separation requirements.