Often when joining an approach (I find this especially on RNAV approaches), the G1000 will perform what I think is called a procedural turn. For example, instead of just say turning left 90 degrees to get onto final approach, the G1000 will have the aircraft turn right 270 degrees, onto final approach. This takes quite some time and I can imagine would totally mess up a controller’s sequencing. My question is do controllers know that a procedural turn will be executed and therefore expect it, or do I have to inform them that I’ll be performing a procedural turn?
In the United States at least procedure turn would mostly be used if radar is not available. When under radar contact, ATC has minimum vectoring altitudes they can use to guarantee terrain clearance. In a non-radar environment the full approach procedure provides terrain clearance for an aircraft provided you comply with the published altitudes. You can know if you are required to do a procedure turn depending on how ATC sets you up for the approach. Take the VOR-28 at KALB, a classic barb procedure turn approach. You can see the IAF is LANGY and the ALB VORTAC is a feeder fix. If ATC were to say “cleared direct LANGY (or direct ALB), cleared VOR-28” they are expecting you to do the procedure turn. If earlier you were flying and they were to say “turn right heading XXX, vectors for VOR-28” you now know that you are receiving vectors to the final approach course and the PT is not required. A helpful acronym to remember when the PT is required is SNERT:
Straight-in - if cleared for a straight-in approach (“ABC123 cleared direct LANGY cleared straight in VOR-28”)
No-PT - if on a published routing labeled no PT (commonly seen on T-shaped RNAVs, see RNAV-19 at KGFL)
Established - already in a hold aligned where the inbound course is aligned with the final approach course
Radar vectors - if receiving radar vectors to the final approach course (probably the most common)
Timed approach - If executing a timed approach
Finally a bit of an issue with how you phrased it. The G1000 is not executing a procedure turn. YOU are. You are the pilot, it is important to make sure that you are flying the plane not the other way around. If your GPS is not doing what you want, either make it or find another way to comply with what you are cleared for, or request something else. (i.e. if you can’t edit your RNAV approach to comply with instructions, request an approach that can be flown off of raw data (ILS, VOR, LOC, etc) or a visual.) Furthermore always make sure you have the approach plate for the approach you’re doing, ideally before you load the box, so you know what to expect.
Awesome, thanks Brendan, that’s very helpful.