Is there a case where a phone still sends data even after airplane mode is active, etc as mentioned above?
Yes. The NSA have admitted they can easily track phones, even with all connectivity disabled and airplane mode turned on:
Even turning off a device’s cellular service, such as when it’s in Airplane Mode, does not totally protect someone from having their location pinpointed, the NSA warned.
“Inconspicuous equipment (e.g., wireless sniffers) can determine signal strength and calculate location, even when the user is not actively using the wireless services,” according to the advisory. “Even if all wireless radios are disabled, numerous sensors on the device provide sufficient data to calculate location.”
Most phones these days are quite happy to allow WiFi and Bluetooth to be activated even when airplane mode is turned on, since you are now allowed to use these things in most aircraft. Further, it is almost impossible for the average person to actually
verify that their phone is not transmitting information via some method.