I flew first class, I placed my iPad in a slot that was in front of my seat. During takeoff, the iPad fell on the floor and slided under my seat. I could not reach it and called for assistance. I was assured that it is there, and not lost. We even joked that during landing, the iPad will slide back. Upon landing the iPad could not be recovered. I provided my contact information, and was told to wait for United to contact me, but I never received any contacts.