Is It Possible For an Aircraft to Float Freely in Air Without Movement?

Yes, it's called a helicopter, or a Zeppelin, Blimp, hot air balloon, or even a VTOL airplane.

VTOL airplane is noted.But my area of interest is big jumbo jets or fighter planes during it's flying.One of my friend told that it is possible for advanced fighter planes by maintaining an equilibrium state in mid air.But I couldn't find any relevant data which support his claim.

Look up the Harrier Jump Jet or the new F-35 Lightning II in the V/STOL configuration.

Sort of yes provided the relative air speed of the head wind its flying into is higher than the air crafts stall speed.

I saw done years ago with a big B52 from our local air base. Its rather odd to see at first until you understand whats going on and how its being done.

OOPS. Already answered.

head wind would have to be about 170 MPH(for a modern fighter), because the forces that would create such a head wind will also create updrafts and downdrafts (think hurricane) your answer is no.

JSF Vertical Landing

I mentioned VTOL already, but in 2nd post OP wanted to know if conventional jumbo jets or fighters could free float.

JFS qualifies as a fighter.

yes it does, but not a conventional take off and landing fighter as the OP has asked about. He acknowledged VTOL or V/STOL aircraft and specifically asked about conventional fighters and jumbo jets.

Yes. But, you'd need a deft touch on the controls.

Small general aviation aircraft sometimes have trouble landing if the headwinds are higher than the stall speed of the plane.

<Never mind. This does not answer the second post.>

Have you seen an UFO by any chance?

Yes. Google "hot air balloons".

"Is it possible for an aircraft to float freely in air and keep the same position in the same altitude without movement?"

Every single post in this thread is wrong!! The correct answer is NO!

There is nothing on this planet that can hover...and keep the same position!!

C'mon people. Read the question word for word. "Keep the same position" to me means zero movement. That's impossible to do in the air unless it was anchored to something. Even then it will still move.

_{(I know what OP meant...just stirring the poo...)}

It depends on what you are referencing the aircraft to (i.e., inertial reference plane).

If your reference point is a single point on the surface of the earth, then if you have sufficient headwinds greater than the aircraft stall speed you can do it.

I remember flying a sailplane into a headwind and with a little work was able to have a negative groundspeed at a constant altitude.

That is going to be pretty hard with a jet's minimum stall speed as someone pointed out. You are going to need a significant headwind (i.e., perhaps the Jet stream under its extreme velocity).

I fly aerobatic aircraft and other types as well. With well over 13K hours doing so I never had one hover (well close once with and extra 500 I flew once). Helios can hover but it depends on type and other issues as well.

Your asking about large Commercial aircraft and they just can not do this. I would suggest reading some of the many books published on the subject of lift. You will then see why this is not possible with todays technology.