What to Do When Your ILS Glide Slope Goes Haywire

During an ILS approach, what should a pilot do if the electronic glide slope malfunctions but the VASI is visible?

• A. The pilot should inform ATC of the malfunction and descend immediately to localizer DH.
• B. The pilot may continue the approach and use the VASI glide slope instead.
• C. The pilot must request a LOC approach and may descend below the VASI as necessary.
• D. The pilot should abort the approach and attempt a visual approach instead.

Answer: (C)

When faced with a malfunctioning electronic glide slope during an Instrument Landing System (ILS) approach, the appropriate response is to request a localizer approach. This is because the localizer provides lateral guidance, while the glide slope provides vertical guidance. By switching to a localizer approach, the pilot is effectively acknowledging that the vertical component is not reliable due to the glide slope failure. Additionally, since the VASI is visible, the pilot can then utilize it visually to maintain the correct descent path. However, it is crucial to adhere to the minimum descent altitude (MDA) set by the localizer approach procedure, while also being cautious about descending below the VASI reading if necessary. This ensures that the approach remains safe and compliant with established procedures. Continuing the approach using the VASI glide slope, as mentioned in the other choices, is not advisable because the VASI is not an official navigational aid for ILS, and relying solely on it could lead to suboptimal decision-making. Aborting the approach or descending immediately to the localizer Decision Height (DH) without proper procedure can also pose safety risks and is not a correct course of action without verifying conditions. In summary, the recommendation to request a localizer approach while being mindful of

When it comes to navigating the skies, there’s a lot on a pilot's plate. One critical moment that can test your skills is an ILS (Instrument Landing System) approach, especially when the electronic glide slope lets you down. Picture this: you’re cruising in for a landing, everything seems on point, and then boom—a glide slope malfunction! What do you do? Let’s break it down.

First, let’s chat about what an ILS is. Basically, it’s like a GPS for the sky, providing pilots with both lateral and vertical guidance for precision landings. But if the glide slope goes kaput? That’s when things can get hairy. The choices laid out in the question highlight various possible responses to this situation. Educating yourself on the best course of action can save you from an unnecessary headache (or worse).

So, option A suggests notifying ATC and descending immediately to the localizer Decision Height (DH). You might be thinking, "Sounds logical!"—but hold up. Simply dropping to the DH without a clear plan can lead to complications if visibility or other factors aren’t ideal.

Then we have option B, which says, “Just keep going and use the VASI (Visual Approach Slope Indicator) instead.” Now, this is tempting, right? After all, the VASI may be visually accessible, but let’s be real—it’s not your go-to navigational aid for the ILS. Relying on it could lead you down a path of poor decision-making, something no pilot wants on their conscience.

Next on the list is option C, which is the star of the show: “Request a LOC (Localizer) approach and may descend below the VASI as necessary.” Why is this the right move? When the glide slope flunks, requesting a localizer approach is your best bet because it keeps your lateral navigation on point. Plus, using the VASI visually to aid in your descent path is both smart and effective. Yes, you’ll need to be mindful of the Minimum Descent Altitude (MDA) the localizer prescribes, but it’s like dancing—you have a rhythm to follow.

Finally, option D tells you to abort the approach entirely and switch to a visual one. While that may seem safe, it could add unnecessary stress to your landing sequence, especially when you have tools at your disposal to assist.

In aviation, decisions weigh heavily, and every pilot knows that safety comes first. By transitioning to a localizer approach when the glide slope fails, you’re not just keeping it safe; you’re proving that you can adapt and respond with intelligence. Plus, staying aware of the VASI lights and adjusting accordingly can put you back on a solid glide path.

So, what's the takeaway? The next time you find yourself faced with a malfunctioning glide slope during an ILS approach, know that requesting a localizer approach is a solid procedure. Keep your focus, monitor your descent path using the VASI, and honor the MDA. That’s the kind of judgment that builds flying skills—and keeps flights safe. Remember, it's all about training your brain to think clearly and act appropriately even in hiccup moments. Safe flying!