Certain circumstances make obtaining an airborne IFR clearance convenient and even necessary. Regardless of how a clearance is obtained, it will contain the same basic information, such as routing, clearance limit, altitude assignment, transponder code, etc. No matter the environment, be prepared to copy the clearance carefully, as you’ll be expected to read back and, most importantly, execute the clearance with precision, regardless of whether you’re flying the airplane or sitting on the ground when the clearance is received. As you might imagine, the less hectic venue of sitting at a standstill on the ramp, void of other distractions and with the opportunity to digest and plan for any clearance modifications prior to flight, is the wiser decision in most situations.
An airborne IFR clearance may be desirable when your departure airport is not towered and does not have a dedicated remote communications frequency. Under these circumstances, local pilots may be able to provide helpful insight. For example, the locals may know that you can raise the approach facility on its published airborne frequency, even while on the ground. Perhaps there is a preferred method for airborne clearances with the local facility that will make the process more manageable and pleasant, as some facilities are less receptive to airborne requests than others.
