Originally Posted by
ATC Watcher
DaveReidUK, no, if it was equipped with Mode S alone ( so ADS-B) you can determine pretty accurately the location as you can deduct/calculate ground speed and rate of descend pretty accurately ( 25ft increments) that is want I meant.
Now whether r it had one or not, a PLN is just telling us what the pilot filed. not what actually is in the aircraft..
OK, thanks for clarifying.
Though I'm still not sure how knowing only altitude from basic Mode S can help with determining location.