How can I pick up a GPS signal from a passenger seat in a commercial airline?

You can use mobile apps like flightradar24 or flightaware to track your flight on your smart phone or a tablet over the WiFi.

My phone will give me a location usong gpogle maps. This Is in airplane mode. But it won't shownthe altitude or speed

How do I help the bad guy figure out exactly where the plane is so that he can do bad things to it?

I will ask questions like I just did.

WHY do you need to know exactly how high you are or exactly where you are second by second?

Wanting to know is not NEEDING to know.

You do not NEED to know.

I think it would be pretty interesting to watch the approach to/departure from airports on a map as they occur.

Bad guys like to do that too so they can shoot down the desired target easier.

ATC needs to know. YOU do not.

a) The phrase "commercial airline" is redundant. All airlines are commercial by definition because they are in business to make a profit. Next time, just say airline.

b) On most phones, "airplane mode" doesn't disable the GPS, but yours might so it may need to be manually enabled when flying. However, the structure of the aircraft is quite effective at blocking the GPS signal and there's not much you can do without an external antenna. The phone pretty much needs line-of-sight to one of the GPS satellites and holding it up to a cabin window doesn't reliably provide that.

Most planes have a tracker on the seat in front of you. Depending on the plane, some even have a camera so you can see what’s happening in real time.

You don't get the gps signal because your phone is in airplane mode.