Tried it, it's well worth playing - great job by Syndicate!

Here is post from ROF forums:

It hasn’t gone unnoticed by us that the number of people player Multiplayer during the week has dropped significantly. Our server is practically empty, except on Sundays. It seems, all there is on offer are Quick Dogfight servers.

If there are players out there that are not interested in Fur-ball or Duel servers, but would like to fly objective oriented missions online, please keep reading.

The alternative to Dogfight mode is Cooperative mission mode. Unfortunately, in Rise of Flight it is impossible to start a co-op mission from a server on your own. Another issue is that you can’t join once the mission has started.
The “Active Front” mission concept has been designed as a co-operative mission, but using Dogfight multiplayer mode so you can join at any time. Even if the server is showing no players in the server, you will find an active world with up to 16 AI planes doing their missions: bombing, patrolling, attacking balloons and engaging each other.
AI flights will take off at regular intervals to achieve an objective, which will be communicated by subtitles after take-off. The player can join these AI flights and help achieve the objective.
Each sortie will last up to 30 minutes.
When selecting an airfield and aircraft from a flight (choose: bomber, escort or patrol) you will be notified how long it takes before the next flight will take off. Since there are multiple flights per side, you should never need to wait longer than 7min 30s.
The number of AI aircraft will be reduced when more human players join and vice-versa to keep the server running smooth.
Only planes needed for the next mission will be available on the airfield. Besides these, there will be a small number of reserve aircraft for individual sorties.
Maximum players per side is 20, thus a total of 40 on the server.

There is currently one mission running, with an early 1917 plane set. When all the bugs have been ironed out and maybe more objectives have added we will also create a version with a 1918 plane set.

Check it out and have fun!

Took on the bombing run:

And managed to kill a guy that was leading interception scouts and finally RTB with one surviving AI bomber:

Was really great feeling, like real coop as script tells you when your flight is ready once you spawn on airfield. Of course you can take off but the point is to wait couple of minutes and go with the flight. Great effort by these map builders, definitely most interesting ROF server so far!