I have used this for some time now. Pretty cool app. Sometimes I see a strange 'new' airline and wonder where its from. Sometimes you can tell origin by its registration number, but not always. Just point the phone at it and it shows where its going!
Best use of this was when I was on vacation a few years ago in St. marteen, USVA. We were on the famous beach where planes land 50' above you. I could search the sky and find a large plane and know when it would arrive. Pretty fun.
Btw, most airlines take off and land around 160 kts (about 175 mph) based on weight and slat/flap type.
Its also fun when u see a contrail, point ur phone and then tell ur friends, "yep, that Delta 787 is on its way to Paris." People are like, wtf?!
Troy