NEW YORK parcel by airmail

Even if airmail, it will still took 1 to 2 weeks to deliver (because US is a big country). If your friend still not get the parcel for so long, there's a chance of lost. Still it's not common to lost a package under nowaday's mailing system. Are you sure you write the correct address? I had experience in our company that the address was mistaken one alphbet and it goes to the receiver's neighbour.
Next time remember to mail it with register (only $13 add to mailing cost). So you can track the pack. Hope the package will get the right way and go to your friend very soon.