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IFR non-towered operations

Several of the ratings in this program have you departing or arriving under IFR at a non-towered field. This document will explain the "one in, one out" procedure used by ATC, the procedure for arriving at an non-towered airport, and lastly, what you can expect to hear when departing from a non-towered airport under IFR.

One in, One out

With nobody working a tower, who is going to sequence arrivals and departures at a non-towered airport, such as Catalina Airport (KAVX)? In VFR conditions, pilots normally sequence themselves, utilizing the advisory frequency (122.70 for PilotEdge, 122.80 on text for VATSIM) to self-announce their position and intentions.  This works remarkably well in the real world, but is predicated on pilots being able to SEE and AVOID one another, the very foundation of VFR flying.

When the weather eases towards the dodgy end of the spectrum, 'see and avoid' simply doesn't work.  With nobody running the show, separation-wise, a mechanism DOES NOT EXIST to allow for more than one airplane to arrive and/or depart under IFR from a non-towered field. 

ATC's primary gig in life, other than falling to their knees and shouting "WHAT ARE YOU DOING??!!" is to separate IFR aircraft. The only way to ensure that two airplanes at a non-towered field are not spontaneously dismantled and distributed liberally about the airport is to make sure that only ONE airplane is operating under IFR in the local vicinity, hence the term 'one in, one out'. 

What does this mean for you, the pilot? It's simple, if there is another airplane departing or arriving under IFR from a non-towered airport, you will not be able to depart or arrive from that airport under IFR until that airplane is either clear of the area, or cancels IFR.  Does this mean that NOBODY can use the airport while the IFR arrival/departure occurs? No, VFR aircraft can still fly as they please (assuming the weather permits VFR flight). So, who is separating the IFR arrival/departure from the VFR guys? Outside of Class B and Class C airspace....nobody! That's why it's important for IFR pilots to maintain a constant vigil for other  VFR aircraft at all times when the weather is VFR.

Assume it's a relatively nice day, with one aircraft conducting an instrument approach into Catalina Airport.  10 miles out, the pilot spots the field.  At the same time, he hears an aircraft calling for IFR departure from the same field. He hears the controller tell the pilot that he'll need to hold for his IFR release as there is an inbound IFR aircraft.  If the weather is VFR and the approaching pilot can see the field, it's considered good practice to cancel IFR and proceed VFR to the field to 'free up' the airspace for another IFR aircraft.  This will be covered in the next section.

Arriving IFR

avx_separation.PNGAs you get closer to the field during your approach to a non-towered field, the approach controller will send you to the advisory frequency where you can announce you intentions on text to sequence yourself with other aircraft at the field.  The controller will use the phrase "report cancelling IFR or missed approach on this frequency, frequency change approved."  Once you land (or any time prior to that), be sure to call the controller back and CANCEL IFR.  

As discussed earlier, the controller will only allow one IFR aircraft in or out of that airport at a time. So, you need to cancel IFR when you deem it is safe to do so.  In favorable weather conditions, pilots are encouraged to cancel sooner rather than later, to free up the airspace. In IMC ('bad' weather), feel free to remain IFR until you are safely on the ground.

A quick reminder, though, just because you are guaranteed to be the only only IFR aircraft conducting an approach at the field, you must keep an eye out for VFR traffic if the weather is good enough for VFR aircraft to be up and about.  The picture on the left was taken during an I-6 rating attempt. N8107T was about to start the VOR/DME-B approach from SXC, crossing SXC at or above 3600, after which he could drop to 3400.  Take a look at NCX57 arriving VFR from the NW, also at 3400!  Completely legal, and even more interesting, ATC is NOT responsible for separating those two aircraft.  So, just because you're "IFR" doesn't mean you don't need to be looking out the window.

Departing IFR

Pick up your IFR clearance from the overlying approach controller.  Once the clearance is given, you will be 'released for departure'. The controller is essentially closing down the airspace to any other IFR traffic, ensuring that you will be the only IFR aircraft arriving or departing the field.  This should be good news to you as you enter the clouds shortly after takeoff, unable to see any other airplanes around you, and potentially before you reach an altitude at which ATC can pick you up on radar.

Clearly, the controller cannot close down the airspace indefinitely. For this reason, your IFR release will be valid only for a certain period of time. You will most likely hear a phrase along the lines of "released for departure, clearance void if not off by 35, time now 15, frequency change to advisory approved."  This means that the clearance is good for 20 minutes. If you are not in the air by 35 minutes after the hour, the clearance is no longer valid.  There are other mechanisms for releasing aircraft, but the technique listed above is by far the most common on online networks. In the scenario above, you would swap to the published CTAF (or 122.80 for VATSIM), and announce your intentions (remembering that there might be other VFR aircraft operating to/from the field). Once airborne and when you deem it is safe to do so, you would contact departure and check in with your altitude.

Now picture that it's a sunny day at Catalina Airport, there are a few VFR aircraft in the pattern, and you decide to undertake an IFR flight to a nearby airport.  You call for your clearance, are told to hold for release, and to expect a 20 minute delay as there are 2 other IFR departures ahead of you. 

Do you have to wait? No, there is another option available to you. You can advise the controller that you will depart VFR and pick up the clearance in the air.  Once airborne, you contact the controller, are issued a squawk code, and then proceed with your IFR flight.

Related Materials
Non-towered Airport Operations (from ASF)
ASF presentation on non-towered operations, covering closed traffic, departures, arrivals and radio calls. Highly recommended.
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