Dispelling Common Myths About IFR Flying

In the world of aviation, misinformation can easily spread, leading to confusion and mistakes. This is especially true in the realm of IFR flying, where precision and accuracy are paramount. Today, we're diving into four prevalent myths surrounding IFR procedures that you might have encountered in your training or discussions at the hangar. Let's break them down one by one and clarify the truths behind these misconceptions.

Myth 1: There are Protected and Non-Protected Sides in Holding Procedures

One of the most common myths you'll hear is the idea of "protected" and "non-protected" sides in holding procedures. This often arises during discussions about parallel entries, where someone might casually mention that an aircraft is on the non-protected side and thus cannot enter. However, this concept is not found in the FAA's Terminal Procedures Publication (TPP).

In a standard holding pattern, both sides have some level of obstacle protection. While the holding side may offer more substantial protection, it's essential to understand that the non-holding side isn't devoid of it. The protection areas can vary significantly based on several factors, including the aircraft's indicated airspeed, the altitude it is expected to hold at, and the distance from the holding fix to the navigational aid used to identify it.

The black racetrack pattern of the hold is depicted within the larger protected area, showing areas of protection on both the holding (north) side and non-holding (south) side.

For example, an aircraft flying a hold at 2,000 feet and 100 knots indicated still has 3.5 NM of protection on the non-holding (south) side of the figure above (segment L-I). Flying higher, faster, and further away from the holding navaid extends this protected distance. Therefore, while it’s wise not to push your luck, deviating from a traditional parallel entry just to avoid the non-holding side may not be necessary.

Myth 2: Glide Slope Intercept and Final Approach Fix Are Always the Same Point

Another widespread myth is the belief that the glide slope intercept and the final approach fix (FAF) occur at the same point on a precision approach, such as an ILS. While the glide slope intercept is marked by a lightning bolt symbol and the FAF is often indicated by a Maltese cross, they do not always align perfectly.

For instance, when flying the ILS approach into Baltimore/Washington International (BWI), the FAF is at 5.8 DME, while the glide slope intercept occurs at 2,000 feet, which is not marked as a specific distance from the FAF. This discrepancy arises because temperature variations can affect altimeter readings. When temperatures soar above standard, the altimeter may read incorrectly low.

The Maltese Cross and Glideslope Intercept are both depicted at the same point, but temperature changes can make the glideslope intercept occur closer or further out from runway.

This means that while maintaining 2,000 feet on the altimeter until intercepting the glide slope, the aircraft will actually be flying slightly higher than the true altitude 2,000 feet MSL. Consequently, the glide slope intercept will occur before reaching the FAF. Understanding this nuance is crucial for successful IFR flying.

Myth 3: VOR Radials Align Exactly with Magnetic Course

Many pilots are taught that VOR radials are based on magnetic course, leading to the assumption that flying along a VOR radial means you're on a direct magnetic course. However, this is not the case. The direction indicated on the chart might not align perfectly with magnetic north.

For example, if you're flying the 360 radial from the Ottumwa VOR, you might expect it to be following a line pointing due north magnetic north. However, due to changes in magnetic north over time, which aren't accounting for in real time by VOR signals, the radial could be skewed.

We're following the 360 radial from the Ottumwa VOR, where the magnetic variation is zero (see nearby agonic line). Thus, you'd expect the 360 radial to be oriented with true north, a straight vertical line, but because magnetic variation changes overtime, VOR radials don't keep up with magnetic course.

The reason behind this is simple: VOR radials are not updated frequently enough to keep pace with the ever-changing magnetic fields of the Earth. This discrepancy can lead to navigational errors if not understood properly.

Myth 4: The Decision Altitude is a Hard Floor

Finally, we come to the myth that the decision altitude (DA) is a hard floor that you cannot go below by even a single foot. Many pilots learn that for non-precision approaches, the minimum descent altitude (MDA) is a hard limit, leading to the assumption that the same applies to the DA.

However, the FAA's Airman Certification Standards (ACS) for precision approaches do not specify an altitude tolerance. The critical aspect is maintaining the needle position and initiating a missed approach when reaching the DA. According to 14 CFR 91.175(c), no aircraft can operate below the MDA without visual references, while no aircraft can continue the approach below the DA without them.

When transitioning from approach descent to a missed approach climb, it's natural for the aircraft to drift slightly below the DA as the configuration changes. While you certainly shouldn't continue the approach below the DA, it’s essential to understand that a gentle drift below during the transition is acceptable.

Conclusion

These four myths about IFR flying are just a few examples of the misconceptions that can circulate among pilots. By understanding the truths behind these myths, you can enhance your IFR flying skills and improve your overall safety. If you’ve encountered other myths or have experiences to share, we’d love to hear them!

For more accurate and simplified IFR training, check out our IFR ground school courses today. Let’s keep learning and flying safely!