The FAA recently updated several airman testing standards documents including the Instrument Rating – Airplane ACS (Airman Certification Standards). The first thing you’ll notice when you go to the FAA’s main ACS webpage and scroll down a few lines, is that you’ll see a link for Instrument Rating – Airplane (FAA-S-ACS-8C) with a publication date of April 2024, that was effective May 31, 2024. However when you click on the link and open the PDF document, the cover page still shows the November 2023 publication date. The Revision History on page ii also still indicates that the last revision was in November 2023. The Major Enhancements page does not clearly indicate the major changes that were made in version 8C of this ACS.

On June 24, I viewed a webinar on these changes that was hosted by DPE Frank Gozzo, who works in the Raleigh, N.C. area. You can view a recording of the webinar here. The following slides summarize the changes:




The biggest change in this ACS is that the FAA removed the following note, which was included in the previous 8B version dated June 19, 2021:

Localizer Performance with Vertical Guidance (LPV Minimums)
Localizer performance with vertical guidance (LPV) minimums with a decision altitude (DA) greater than 300 feet height above touchdown (HAT) may be used as a nonprecision approach; however, due to the precision of its glidepath and localizer-like lateral navigation characteristics, an LPV minimums approach can be used to demonstrate precision approach proficiency if the DA is equal to or less than 300 feet HAT.

Under the new revision 8C, any approach with “approved vertical guidance” can be used to satisfy the Precision Approach task. So what is “approved vertical guidance”? The current ACS has this to say about the Non-Precision Approach task:

Task A. Non-precision Approach

A non-precision approach is a standard instrument approach procedure to a published minimum descent altitude without approved vertical guidance. The applicant may use navigation systems that display advisory vertical guidance during non-precision approach operations, if available.

FAR 1.1 offers the following definitions:

Nonprecision approach procedure means a standard instrument approach procedure in which no electronic glide slope is provided.

Precision approach procedure means a standard instrument approach procedure in which an electronic glide slope is provided, such as ILS and PAR.

A local DPE who we know personally had this to say when asked about the use of vertical guidance on instrument approaches during practical tests under the new ACS:

“[Orlando] FSDO has not given guidance, and in absence of said guidance, I don’t see a reason why [applicants] can’t use vertical guidance if it’s available. That’s what they will be using in real life and the FAA actually prefers using vertical guidance as a way to avoid dive-and-drives and execute a more stable approach. They will just need to remember to level off at MDA and drive to MAP and not treat the MDA as a DA.”

In the webinar, Mr. Gozzo suggested that DPE’s can disable WAAS to make vertical guidance unavailable when the applicant is attempting to demonstrate a non-precision approach using an RNAV approach with LPV capability. I have a big problem with this as a flight instructor, flight school manager and aircraft owner. The problem with manually disabling a perfectly functional WAAS GPS system is that depending on your system, WAAS might not re-engage automatically the next time the avionics system is booted up. This could cause glide path information to be unavailable to a pilot in IMC, when it is most needed. My concern is that manually disabling WAAS just to demonstrate a nonprecision approach on an instrument check ride could present a safety issue for the next pilot who flies that airplane, especially at night or under IFR when glide path information enhances safety during an instrument or a visual approach.

I tested this on our Cessna 152, N152DM, which has a WAAS enabled Garmin GTN650 IFR GPS. While the airplane was parked on our ramp, in full view of GPS satellites, I turned on the avionics and let the GPS boot up. On the GTN650, to disable or enable WAAS, you go to the main menu and select SYSTEM -> GPS Status -> SBAS -> WAAS. According to the Garmin user manual, “SBAS (Satellite Based Augmentation System) is a system that supports wide area, or regional, augmentation through the use of additional satellite broadcast messages. WAAS, EGNOS, MSAS, and GAGAN are known SBAS providers. WAAS provides SBAS service for Alaska, Canada, the 48 contiguous states, and most of Central America.” The manual tells the user how to select the appropriate SBAS provider depending on which part of the world they are operating in, which for us is WAAS. There is no mention anywhere in the manual of a good reason why a user should ever want to disable WAAS once it is selected. To find out whether WAAS would automatically re-engage, I disabled it by un-selecting it on the SBAS page, turned the avionics off, waited a minute, then booted the GTN650 back up. As I suspected, WAAS  remained unselected. Not good!

Regarding nonprecision approach procedures, the new ACS also states:

The evaluator must select and the applicant must accomplish at least two different non-precision approaches in simulated or actual instrument meteorological conditions:

  • At least one procedure must include a course reversal maneuver (e.g., procedure turn, holding in lieu, or the course reversal from an initial approach fix on a Terminal Area Arrival).
  • The applicant must accomplish at least one procedure from an initial approach fix without the use of autopilot and without the assistance of radar vectors. During this Task, flying without using the autopilot does not prevent use of the yaw damper and flight director.
  • The applicant must fly one procedure with reference to backup or partial panel instrumentation or navigation display, depending on the aircraft’s instrument avionics configuration, representing a realistic failure mode(s) for the equipment used.

This can be accomplished with two different RNAV approaches with LPV using vertical guidance, as long as the applicant levels off at the LNAV MDA. Also, even though the ACS still says “in simulated or actual instrument meteorological conditions” we have been informed by multiple DPEs in our area that the FAA has instructed them to not file IFR on behalf of the applicant in order to complete the flight portion of the practical test in IMC. The whole flight must be conducted in VMC, even though the ACS suggests otherwise.

I find it somewhat ironic that the FAA has spent and continues to spend so much time, energy and money emphasising the need for stabilized approaches and touting the benefits of NEXTGEN including WAAS/LPV — both of which are very good things — yet we still have VOR approaches and LNAV approaches without vertical guidance. You can view the current IAP inventory here. According to that FAA site, there are currently about 1,300 VOR approaches, about 1,300 ILS approaches, and about 6,500 RNAV approaches, but it doesn’t specify how many of the RNAV approaches are LNAV only (no vertical guidance). Here in the Jacksonville, FL, area, I know of only one RNAV approach that does not offer vertical guidance, the RNAV 22 at Fernandina Beach (KFHB). All the others offer LPV. Yet applicants have to fly two nonprecision approaches on the check ride but only one precision approach. I don’t think there is anything in the current ACS that addresses the real dangers of dipping below minimums or flying an unstabilized descent profile, especially on a nonprecision approach. This video, though, says it all: