I was tracking two planes for the same company.
Both have the same departure and arrival airport and took off within minutes of each other, but only ONE of the planes has a track on the map.
What about the other one?
http://flightaware.com/live/flight/TSU151/history/20070321/1628Z/KPTK/KDVK
http://flightaware.com/live/flight/TSU361/history/20070321/1633Z/KPTK/KDVK
One flew VFR and one flew IFR?
If one was flying VFR, it wouldn’t have even made it into FlightAware. The flight was in the system, just not showing a track log or tracks on the map. Both flights now have a track log and tracks on the map.
Try reloading the page; it should be fixed now.
Part of yesterday’s downtime should have eliminated (or at least greatly reduced the frequency of) these missing track events.
Sorry for not being verbose enough in my response. I understand how aircraft get into the system, so I meant that they had filed a FP but instead chose to fly VFR.
They were both flown IFR on an IFR flight plan (per company policy).
Now, why does one of them have weather while the other doesn’t?
Thanks for all the help! 
Weather is only displayed for the most recent flight by a given flight number.
Missing track problem appears to still exist at flightaware.com/live/flight/N1943L
All history flights missing the track line
Also some prior flights I get
FlightAware couldn’t find N1943L just yet.
Please double-check the flight number/identifier. If you typed it in correctly and it’s still not showing up, or you’re not completely sure of the flight number, you should use the FlightAware Flight Finder. If you know the origin and destination of the flight, it will help you find the proper flight number/identifier.
flightaware.com/live/flight/N194 … /KBLF/KDMW would be one where I get the above error.
Track log still doesn’t work.
This plane, as of 0100Zulu, while enroute, still has no flight path.
It does now.
Yes, I know. The path only shows up after they land, not while enroute. 
Something is seriously wrong.
Flight from KPTK - KCMH, yet the track goes from Hawaii:
flightaware.com/live/flight/N12F … /KPTK/KCMH
This falcon has no flight track or flight history:
flightaware.com/live/flight/N49K … /KPTK/KLUK
I know I could go on and on, but I’ll stop. Ever since the downtime, there have been a ton of flights with no tracks. 
Other than that, love the site! 
I noticed N54467 on the airport radar map today at about 2:00 PM, but when I check LIVE TRACKING, it doesn’t show any recent history.
Whuddup widdat?
VFR flights can show up on the map when they are using flight following, but that same VFR flight won’t show up in the aircraft activity since it’s not IFR.
Trying to track my mom and sister aboard AA346.
They are not trackable per FA but are other sites.
Why is this?
Ahhhh, okay. Thank you.
The FAA sent us a cancellation message 5 minutes after departure.
Right, but there is another flight plan that is active with no flight tracking. It was there for about 10 mins then dropped off.
Oh well!