A CFI’s guide to briefing, loading, and flying precision approaches is our next topic in the training series that covers various aviation topics applicable to flightsim. This article is written by CFI Kevin Claus | TPC3389. Kevin is part of TPC Training Team and can be reached via DISCORD, if you have any questions.

What is a Precision Approach?

A precision approach is a type of instrument approach precision used by general aviation and air carrier traffic to help the pilots guide the aircraft from the arrival environment (your initial descent from cruise altitude) down to the runway environment. The term precision implies the existence of non-precision approaches as. Where the two differ is that the precision approach provides both lateral and vertical guidance to the pilot to assist in guiding the aircraft to the runway.

The most notable example of a precision approach is the Instrument Landing System (ILS). An ILS approach consists of lateral guidance in the form of an array of localizer beacons, and vertical guidance from a duo of glide slope antennas. The aircraft will read these two components via receivers, and use those to determine its position relative to them to provide the pilot with a means to correct the aircraft on the approach to the runway. As long as both the localizer and glide slope are functioning, the ILS approach is considered a precision approach. If there is no glide slope, the approach becomes non-precision.

Before You Fly a Precision Approach

The first step of flying a precision approach is selecting the approach among the many an airport can possibly have. For this scenario today, we will be flying into the John Glenn Columbus International Airport in Columbus, Ohio (KCMH). On the particular day that I am writing this, the winds are pretty gusty out of the Southwest, therefore I am inclined to pick one of their two West-facing runways; 28L and 28R. Of those two runways, I will choose runway 28L.

Since we are trying to select a precision approach to fly, we now need to find the chart for that approach among the charts for that particular runway. There are many ways to find the approach charts for an airport in the United States. For flight simulation, you can choose to have a subscription for Navigraph which will give you access to the approach charts provided to them by Jeppessen, or they are available for free from the Federal Aviation Administration (FAA) via a website called SkyVector (skyvector.com).

A selection of the instrument approaches you can choose from at the airport via SkyVector is provided down below. You simply right-click on the airport and hover your mouse over the airport name to find the chart selection menu for that airport.

KCMH Instrument Approach Selection (Credit: SkyVector)

From here you find the precision approaches in the list. All ILS approaches are considered precision approaches according to their charts, so we will choose an ILS approach, denoted by the fact that they start with the letters “ILS” and they are usually at the top of the Instrument Approach Procedures section of the list. Here we see we have approaches for both runways 28L and 28R, so we will pick ILS approach runway 28L.

Briefing And Loading the Approach

Once you click on that approach, you can view it in your browser or download it as a PDF. Below is what that chart looks like after I have taken the liberty of highlighting a few key details.

ILS Runway 28L KCMH (Credit: SkyVector)

Here are all the details on the chart that will be important to you in the chart, as highlighted:

The type of approach, to what runway, and at what airport
The effective dates of the chart to ensure the charts are current and accurate
Localizer frequency and inbound course
Touchdown Zone Elevation (TDZE)
Name and minimum altitude at the Final Approach Fix (FAF)
Decision Height (DH) and minimum runway visibility range (RVR)
Missed Approach Procedure
Type of approach lighting you can expect to see.

Once you have become familiar with these details about the approach, now comes time to load the approach into the aircraft. This will depend on the aircraft of choice, but there are a few standard procedures that exist in all aircraft. First, you will go into the aircraft GPS or FMS and ensure that you are navigating to the correct airport. In this case, we will make sure that our intended airport to land at in the GPS or FMS is KCMH.

We can then go into the approach selection page of your system and select the ILS approach runway 28L. We then verify in our aircrafts specific flight plan synoptic page that our final approach fix is the correct identification and that we have the correct bottom altitude in that selection. All of this will allow the GPS to help us identify this point from which we will descend via the approach down to the runway. Next, we go into the aircraft's navigation radio and verify that the frequency for the localizer is set correctly, in this case 111.75 will be the correct frequency to set or verify is set. You then set the correct inbound course on the localizer to allow the aircraft to fly the correct inbound heading to the runway as specified on the chart. There may be cases on other approaches that setting the incorrect inbound course in the navigation system will possibly cause the aircraft to navigate into other aircraft or even terrain in some extreme circumstances, so it is important to verify that course is correct. Our next step is to note the decision height and touch down zone elevation for the approach. Before we start descending, we will need to make sure we know where we need to see the runway before, to be able to make the timely decision to go-around and attempt the approach again before it is too late. In this case, we will be either at 1,015ft MSL (above sea level, the indicated altitude of the aircraft), or 200 ft AGL (height above the ground, if your aircraft is equipped with an altimeter that reads out height above the ground while descending). Once all of that is set and you are made familiar with all of these details, we are now ready to conduct the approach.

Flying a Precision Approach

Now that all the details are set up in the aircraft, let’s fly the approach. You can either vector yourself onto the approach while on UNICOM, or you will be vectored onto the approach by a CENTER or TRACON controller. Preferably, the intercept angle will be within 30 degrees of the final approach course, before the final approach fix, and at an altitude greater than or equal to that minimum height depicted at the final approach fix on the chart, in this case roughly between a 250 and 310 heading to intercept the localizer.

Headings to Intercept the Localizer (Credit: Infinite Flight)

Having been set up on an adequate intercept heading, make sure your aircraft’s navigation is set up in NAV mode instead of FMS or GPS mode, depending on the make and model and type of avionics setup included. At this point, either the horizontal situation indicator (HSI) course deviation indicator (CDI), or the navigation display of the aircraft should depict a “needle” that will indicate how centered you are on the localizer course. This will look something like this if you are in an older-style analog cockpit. NOTE: THE HEADING SELECTED IN THIS EXAMPLE WILL BE THE LOCALIZER COURSE, NOT SELECTED HEADING.

CDI Depiction for Localizer Intercept

Once you get within one “dot” as shown above, you will be in a position to turn onto the desired heading for the inbound course of the localizer. Once on that heading we make adjustments to keep the needle centered in the instrument while we get closer to the final approach fix.

Approaching the final approach fix, there will be a second, horizontally-oriented needle. This is your glide slope pointer, indicating where you will initiate your descent. As long as you are at the minimum altitude at the final approach fix, this needle will be centered in the gauge exactly when you cross that fix. Upon reaching the intercept of the glide slope, you should have the aircraft approximately configured for the approach (flaps 10 degrees in the Cessna 172, APP flaps in Diamond aircraft, and flaps 5 or 15 in the Boeing 737).

You will now descend to keep the glide slope indication centered in the gauge, and adjust the course to keep the localizer needle centered. If the localizer needle deviates to the right, you will turn right to re-center it. If the glide slope needle indicates higher than centered, you will slow your descent slightly and the needle will gradually re-center.

Glide Slope and Localizer Deviations (Credit: PilotsCafe)

This gauge or similar will be your primary means to descend on the precision approach. While descending, monitor your altitude; you’ll have to keep your decision height in mind relative to your current altitude as you look for the runway.

In low-visibility conditions, the first part of the runway environment you are going to see out of the window is going to be the approach lighting system. Below are examples of all possible approach lighting systems. In our case, we will be looking for MALSR lights according to the chart.

Approach Lighting Systems (Credit: FAA)

Approaching our decision height, we will be looking for these lights, or other possible indications of the runway environment. Other things to look for include the PAPI lights, VASI lights, threshold lights, touchdown zone lights, and many more (14 CFR 91.173 is the regulation that pertains to who constitutes the indications of the runway environment if you would like to know more). Once you reach the decision height/altitude, if you do not see these parts of the runway or the runway itself, you fly the missed approach procedure and you notify either ATC or advise on the appropriate CTAF frequency that you are “going missed” off of the approach.