ANR won't help at all with noise coming in via the intercom - it only blocks out ambient noise (ie the noise which comes in through the shell of the earcup).
If you are only getting this noise when using the intercom, then the noise sources you need to address are the microphones on the headset and the intercom.
Might be worth trying microlight-style headsets and intercoms (see if you can borrow some from somewhere), they are generally designed to work in high-noise, windy environments. The gear I sell has a band-pass filter in it to block out unwanted parts of the audio spectrum (ie noise) and microphones designed to be less sensitive to wind buffet and noise.