KGRF has a SID requiring a climb gradient of 469 FPNM for obstacles. In the takeoff minimums section, there are takeoff minimums listed for a VOCA (Visual Climb Over Airport) but nothing else. My understanding was that a VCOA was an alternative if you did not want to fly an ODP (Obstacle Departure Procedure). But this airport only has a SID (and no ODP?)Which would lead me to believe that you could fly a diverse departure out of this airport. However if you could fly a diverse departure, what would be the point of even having a VCOA since the required climb gradient for both would still be 200 FPNM?
Edited based on new information… I communicated with both the procedure designer for Gray AAF and with the FAA’s Flight Standards office. There are 2 answers for this question:
First, the VCOA at Gray was created for ATC purposes rather than obstacle clearance, so this is not a good example for the question asked. The procedure designer says that you can fly a diverse departure at this location.
Second, per the 8260.46J (and has been the case for several of the previous iterations), “When the Flight Procedures and Airspace Group will not approve a CG in excess of 500 ft/NM (600 ft/NM for helicopters) and any of the obstacles forcing such a CG are located outside the ICA (extended) greater than three SM from DER; a stand-alone VCOA procedure may be used as the only option available for obstacle avoidance.”
Therefore, in general the VCOA may be the only option. This, however, is the only time a stand-alone VCOA would occur. Otherwise, one should expect to see a climb gradient higher than standard, takeoff mins higher than standard, or an ODP in addition to the VCOA.
I believe you can not fly a diverse departure if a VCOA is published. (Unless you're part 91, in which case takeoff minimums and ODPs aren't mandatory to begin with). The takeoff minimums say "9900-5 for VCOA," not "9900-5 for VCOA or standard otherwise."
There is some support for this in TERPS standards. From Volume 4, 1.4.6:
b. Where obstacles more than 3 statute miles from the DER penetrate the OCS:
b. (1) Publish standard takeoff minimums with a required CG to a specified altitude, and
b. (2) Develop a VCOA procedure to an altitude that will provide obstacle clearance without a CG, and/or
b. (3) Develop a specific textual or graphic departure route to avoid the obstacle(s).
From the wording it's clear that (3) is not mandatory if (1) and (2) are published. That is, a VCOA (2) may be mandatorily published without an ODP (3).
An example of an airport where some runways have only VCOA published where a diverse departure is clearly not possible is KBIH. At KBIH, there is an obstacle only 17 nautical miles from the airport that is over 10000 feet above airport elevation. No matter what runway you take off from, if you turn toward that obstacle out of the initial climb area, you won't get anywhere close to clearing it with a 200 fpnm climb gradient. Such an obstacle is high enough that it can't exist anywhere within 46 nautical miles of the airport and still allow for a diverse departure.
KBIH does have ODPs published for other runways. But since each runway is analyzed separately under TERPS criteria, I don't see how this is really any different from an airport with only a VCOA published.