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Just because your aircraft is IFR certified and you have a chart doesn't mean you can fly every type of procedure. How do you know when you can fly an LPV? What about an RNP? Or a specific SID?

It all starts with understanding the types of equipment required of you, the capabilities of your avionics, and when to tell ATC you're unable.

Where are the requirements published?

Basic IFR requirements are published in FAR 91.205 and also include all VFR day and night equipment, but some procedures have additional requirements above these general requirements.

You'll find these additional requirements under the approach notes or under equipment required on your EFB.

Common Equipment Requirements

The first step in determining whether you're able to fly a procedure based on your aircraft's equipment is in the procedure name. If you plan to fly a VOR/DME approach, you'll need both, but most general aviation aircraft no longer have DME, so you'll substitute DME with GPS in accordance with AIM 1-2-3.

Procedures, such as CAT II / III and RNAV (RNP) approaches, require special authorization from the FAA, preventing most general aviation pilots from flying these procedures. Many of these approaches also require radius-to-fix (RF) legs, which not all avionics support.

Understand your aircraft's capability

You plan to rent a Piper Archer (PA-28-181) from your local flight school, equipped with a G1000 NXi. How do you know you can fly an LPV approach? The answer lies in the AFM.

In Section 1, you can find the G1000 GNSS Navigation and System Equipment Approvals, here you'll find the specific approvals for navigation under IFR for en-route, terminal, non-precision approaches, and approach procedures with vertical guidance, including LPV.

If the avionics for the aircraft you're flying were installed after-market, then you should look in the avionics STC manual.

GPS Equipment

RNAV specifications exist to standardize the lateral accuracy of approaches. The more accurate the GPS system, the lower and closer to terrain and obstacles you're permitted to fly.

RNAV (RNP) approaches charts are authorization required (AR) procedures, and most GA pilots won't find them in their avionics databases, but RNAV (GPS) approaches are available to you with any IFR legal GPS system. As a rule of thumb, your avionics only show the types of RNAV approaches you're permitted to fly.

When you look at a new chart, consider:

1. 1. Checking the procedure name.
2. 2. Can my avionics load this approach?
3. 3. Can I accept this instrument procedure? If not, have an alternate plan in mind.

If the answer to these questions is no, let the controller know you're unable to fly the procedure because you don't have the required equipment.

Example: "Cirrus 123BD, unable MMOTO2 departure procedure, we're not GPS equipped, request PEBLE6 departure instead."

If you're in-flight and a controller issues a clearance for a procedure, like an approach that you don't have the equipment to fly, tell them before starting the procedure.

Example: "Cirrus 123BD, unable RNAV Y 22L, request the ILS 22L instead."

Both in the air and on the ground, when you tell a controller you're not able to accept a clearance for a procedure, it's best to have an alternate procedure in mind that you can request.

When was the last time you told a controller unable? Tell us in the comments below.

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