As a long term user of Flight Track Pro, I was shocked and disappointed to discover that Mobiata just switched it off.
I've done a bit of research and found mi Flight Track, which seems very similar to FTP and there is a sister app, mi Flight Board. Maybe not as great as FTP, but a close second maybe. The paid for version is a one-off £3.99 or you can buy a bundle of all the three mi Flight apps for £12.
I hope this is of help