Why can't an iPhone 6 and a mid-2011 MacBook Air see each other in AirDrop?
Your mac (and mine too) is not compatible with airdrop between mac and iOS

System Requirements
To see if your Mac works with AirDrop, make sure you’re in the Finder by clicking the desktop (the background area of your screen), or by clicking the Finder icon in the Dock. Then, check to see if AirDrop is listed as an option in the Go menu. If you don't see AirDrop listed, your Mac doesn't support this feature.
In order to transfer files between a Mac and and an iPhone, iPad or iPod touch


your iOS device needs to include a lightning connector
your iOS device needs iOS 7 or later installed
your Mac needs to be a 2012 or later model with OS X Yosemite
installed
Your Mac and iOS device both need bluetooth and Wi-Fi turned on. You
do not have to be connected to a specific Wi-Fi network



source:http://support.apple.com/en-is/HT203106