“Unusual” is a subjective word, but there are many instrument-rated pilots who never encounter these types of operations. If you fly IFR irregularly, perhaps only from towered airport to towered airport, then having this knowledge and being proficient in its use will add to your IFR toolbelt and keep you prepared for different situations.
Getting out: the VFR departure
You may subscribe to the philosophy of always filing and flying IFR, even on perfectly clear VFR days. That’s smart, it keeps your skills sharp. Regardless of the weather, ATC must maintain IFR separation — so you might be disappointed to call for your clearance and be informed to expect a substantial delay because of the IFR departures ahead of you.
If conditions are VFR, you don’t have to wait. You can advise the controller that you will depart VFR and obtain your clearance in the air.
You must remember that until you obtain your clearance, you are VFR, and all VFR weather minima and cloud separation distances apply to you; you must also maintain an appropriate VFR altitude. When airborne, establish radio contact with the controller to get your clearance and squawk code so that you can proceed IFR.
Getting out: the untowered airport departure
The main difference here is that the clearance you are issued will include a validity period to ensure proper IFR separation. This will come at the end of your clearance: “Cleared for departure, clearance void if not off by 0915, time now 0910. Report airborne on this frequency. Frequency change to advisory frequency is approved.” ATC may even include a “valid time” that you cannot depart before.
When you fly from towered airports you are probably accustomed to calling Clearance Delivery from the FBO ramp prior to taxi. But for an untowered departure’s clearance the delta between the current time and the void time may be quite tight, on the order of just a few minutes. For this reason it’s customary to obtain this clearance with the engine started and pre-takeoff checklist completed, right in the run-up area.
Who do you call for the clearance at an untowered airport? There are a few options, listed roughly by preference:
- The provided Clearance Delivery freq on your approach chart or DP
- The overlying Departure / Approach Control freq
- The overlying Center freq
- A nearby FSS RCO freq
- Call the FS21 Clearance Delivery phone number from your cell
- Call Flight Service from your cell (1-800-WXBRIEF)
- A GCO listed in the AF/D. This actually initiates a telephone call through your radio, and takes mic clicks to initiate: 4 for Clearance Delivery, 6 for FSS.
Getting out: departing IFR from an airport with no SID or DP
Congratulations, you just discovered an airport with what the FAA calls a “diverse departure” and what ICAO calls an “omnidirectional departure.” In basic terms, the reason that no ODP exists is because there are no obstacles that mandate it. (See this IFR Refresher article for the exact specifications.)
Caveat: this section only applies to airports having at least one instrument approach; only such airports have been evaluated for obstacle clearance. You’re on your own departing airports lacking an IAP.
You’ll know your airport has a diverse departure if there’s no SID, no ODP, no “inverted T” in the plates. If ATC hasn’t given you instructions to the contrary, take these steps:
- Cross the departure end of the runway (DER) at or above 35 feet.
- Climb runway heading to 400 feet AGL.
- Turn on course and maintain a 200 feet-per-nautical-mile climb to the IFR MEA.
The lack of any ODP, by definition, means that the above steps will guarantee obstacle clearance.
Don’t forget to convert feet-per-nm into feet-per-minute for your plane using the table.
Getting in: the pop-up clearance
This is the situation where a VFR aircraft calls ATC and requests an instrument clearance without having previously filed an IFR flight plan. The common use case: an instrument-rated pilot is flying along in good weather, but learns that conditions at the destination have — surprise! — deteriorated below the VFR forecast that was expected.
To get a pop-up, determine your nearest Approach or Center radio frequency. Establish radio contact with them (e.g. “Seattle Center, Skyhawk 12345, request.”). Provide your location (e.g. “3 miles east of the XYZ VOR at 5,500”) and explain that you need an IFR clearance to so-and-so airport.
ATC may be too busy to accept your request. Your fallback is to radio a Flight Service Station and file mid-air. This takes longer because you’ll have to go through the rigamarole of filing an entire flight plan: route, time, fuel, souls on board, altitudes. (This is one of those times when having a second pilot on board to work the comms while you aviate and remain clear of weather is very helpful.) After filing with FSS you can switch back to ATC and they should have your flight plan.
Pop-up clearances can occasionally be unpopular with ATC because of workload, but pop-ups are legitimate and safe.
Getting in: the untowered airport
Some pilots only file IFR to towered airports, but untowered arrivals aren’t difficult. You simply change to the advisory frequency when instructed by ATC; this will sound something like “Report canceling IFR or missed approach on this frequency, frequency change to advisory frequency is approved.” Announce your position and intentions on the CTAF like you would for any untowered airport, and radio ATC as instructed when you have successfully landed or gone missed.
Getting in: filing to an airport without an approach
It’s perfectly legal to do this, with a weather caveat: you must maintain VFR while you descend from the MEA, approach, and land.
You must file an alternate in this situation.
The “cruise” clearance
You might encounter this when you’re out in the boonies and traffic is really light. This clearance permits you to fly all the way to your destination and execute any IAP there.
You “own” your given altitude all the way down to the published MEA, and must simply report altitude changes as you normally would.
Upon reaching the destination you’re automatically cleared for the approach of your choice.