Originally Posted by
Kiowa
Hi guys, a friend of mine is working on a novel. He asked me this, but I don't know the answer. Can you guys shed some light?
I'm working on my second book and I need your help with some dialog/procedures. Pair of F15s patrol over the city. How are they cleared AFTER departure? Do they get free rein to just buzz around town? I know the general speed restrictions below 10,000, are fighters beholden to that as well and if they are, would they be permitted to go balls out above 10k? Do they have to squawk transponder codes? Been listening to Livestream of ATC. Man, gripping stuff. You lucky so-and-so.
And he clarified the following:
It's not combat, just a routine patrol over the city like we have every morning at 10 am here in Portland. With so many commercial and civilian planes buzzing in and out of the airspace, I wonder if there are temporary airspace restrictions in place while they buzz around.
This vet thanks you all in advance 
It would help if your friend expanded a little on his reason for the F-15s in this particular segment of the book. It might help to create plausible suggestions for getting them into the circumstances in which he wants to include them.
There really would be no reason for a "routine" patrol over a city. That sort of implies the city itself is in need of patrolling by F-15s which isn't normal.
The F-15s in Portland that are seen on a regular basis by folks in the local area/city are usually doing one of two things. They are either on their way to train in a particular designated piece of airspace reserved for their use or they are the air defense alert aircraft on a live or training scramble. The training aircraft will normally not be armed with live missiles and live rounds in their cannon. One caveat to that would be if they were launching on a training sortie over water to shoot the gun against a towed target. The air defense aircraft (live or training) will always have some mix of live missiles and a hot gun.
F-15 tech order climb speed after takeoff is 350 KIAS until by virtue of their climb they reach .9 mach, then they hold that. They are allowed to fly that speed below 10,000. They usually have no reason to exceed that above 10,000 if they're just heading to the working area on a training mission (although they could as long as they stayed sub-sonic). On a training mission, going supersonic is only allowed in specially designated working areas over land or in warning areas over water. There might also be additional restrictions about altitude, distance from land and vector in relation to populated areas.
Those rules go out the window if they were on an active air defense scramble to intercept an unknown aircraft. Speed and altitude as needed to get the mission done.
Yes, they would normally have a mode 3 squawk like any aircraft as well as a 2-digit mode 1 squawk, 4-digit mode 2 and an encrypted military mode 4.
Simply launching fighters from Portland on normal training missions would not require any special restriction to airspace. The Eagle's radar is more than capable of helping its pilots de-conflict from other traffic as they come and go. There may be temporary restrictions put in place during an active air scramble launch, but those would probably be relatively short (until the fighters launched). Sometimes fighters have set up CAPs (combat air patrols) to enforce a restricted fly area in conjunction with political events or the location of a particular politician. In that case the restriction would be to keep civilian aircraft away from the area in concern rather than simply because of the presence of the fighters.
Normally, for training missions, it's likely the F-15s fly the same SIDs and STARs the airliners are flying, especially if the weather is down. The ADF alert aircraft may have specially coordinated SIDs for their scramble departures designed to get them up and away from the airport traffic and on their way as quickly as possible.