Let’s put it all together departing Houlton, Maine (KHUL) and using the bigger runway of 05-23. This airport has two instrument approaches, so it’s been surveyed for departures. Runway 05 has no published departure procedure, which means we’d use the default procedure of fly runway heading until 400 AGL before making any turns. Runway 23 has a departure procedure: Climb heading 229° until 1000 feet before any left turns. Houlton’s elevation is 489 feet, so even that’s only a climb to 511 feet AGL.
However, Runway 5 requires 300-foot ceilings 1.5 miles of visibility if you can only climb 200 feet per nm. If you want to take off with less than that, you should be able to climb 340 feet per nm to 900 feet (411 feet AGL) before continuing to climb at 200 feet per nm. Departures from Runway 23 require higher ceilings and a higher climb rate of 389 feet per nm up to 1000 feet. That’s 778 feet per minute with a groundspeed of 120 knots, or 584 feet per minute at 90 knots. Not out of reach for most GA aircraft that might fly IFR, but important to know before takeoff. Out west and in the mountains, there are plenty of departure procedures that require climb rates greater than a non-turbocharged light single can manage.
Once passing 1000 feet and with no instructions from ATC otherwise, we revert to a normal diverse departure, and—barring instructions otherwise—head on any route that makes sense given our clearance. If we were joining the V471 airway southwest bound, we’d need to reach the MEA of 2600 feet within 25 nm of Houlton. (The *2000 means we have obstacle clearance above 2000, but we’d need 2600 for assurance full navigation and communication.)
If we were joining V352, however, we’d need to reach 6300 feet within 25 nm. That’s steeper than 200 feet per nm. That’s not hard, but it’s our responsibility, not ATC’s. If, for some reason, we can’t get that high within 25 nm, we need to work out a solution. We’d want to notify ATC of this and probably ask for their blessing on something like an ad-hoc hold we could climb in before continuing westbound.
Suppose we were off route and climbing on a course just south of V352. In that case, the safe altitude would be the OROCA of 7400 feet. Again, unless we knew we had adequate terrain clearance on that specific route, we’d want to get that high within 25 nm of Houlton.
Of course, a glance at the Sectional Chart shows you’ve got way more buffer than it might appear. There are also clues on the en route chart. But the takeaway here is that unlike approaches where you pick a procedure and fly it, safe departures require a flow chart of “if” statements to arrive at the requirements. Those requirements only provide the loving embrace of charted protection for a limited distance. After that, you’d best be safely up in the system one way or another.