"Remember that, up until the recent past, Gov't employees were not allowed to accept FF miles for Gov't paid fares. It was originally viewed as an unallowed gratuity, but that view has changed and employees are now allowed to accept FF miles. The seats assigned to FAMs for missions are non-revenue seats and so the collection of FF miles is strictly forbidden."

Somewhat off-topic, but I feel compelled to clear up a misconception myself. I've lived through every era of FF miles versus the government. Here's a brief history:

1. We were forbidden to join FF programs and accrue miles earned on official travel;
2. We were advised it was OK to enroll, but you could only accrue miles for personal trips;
3. It was OK to enroll and earn miles for official trips, but you should have two accounts -- one personal and one for government trips;
4. You were "encouraged" to use your earned government miles for government trips. Some people tried, but government travel offices couldn't figure out how to book the trips;
5. You could use your government miles for business-class upgrades on official travel (no first class permitted, so the experienced government traveller always flew on 3-class aircraft);
6. Finally, Bush II decided you could use your miles for free tickets -- no restrictions.

For many years, lots of us were earning miles that expired because we couldn't use them. There was always the argument over who owned the miles. The government said they did; the airlines said the traveller did. Rumors in the late 1980s were that the airlines were going to force some sort of confrontation with the government over the ownership issue as a means to get out from under the tremendous financial liability of FF programs.

I believe FAMs, like any other federal employee, are permitted to enroll in FF programs. It's purely a business decision by an individual airline to decide to award a passenger -- FAM or not -- miles for a given trip. For example, I doubt a FAA inspector will earn miles for a trip they take while doing an inspection. This is one example where I could see a prohibition on joining a FF program for conflict-of-interest reasons. I don't really see a COI for FAMs.