You can set airplane mode automatically when you are connected to WIFI on you favorite Android (4.2+) phone provided you have:

1. 4.2+ Android Phone

2. Root Access

3. Tasker

4. Secure Settings

General instructions here:

https://groups.google.com/d/msg/tasker/HgjCbDOvGp4/DexKczO4d3YJ

This is not for novice users. Gaining root access and using Tasker/Secure Settings is not an easy path.