By Javier Rollon · 2022-06-10
I get more support emails about ILS approaches than anything else. More than FMS programming, more than engine starts, more than "my download won't install." The instrument landing system is simultaneously the most important skill in instrument flying and the most poorly explained concept in flight simulation.
So here's the guide I wish someone had given me when I started. No jargon walls. No assumptions. Just the actual procedure, step by step.
Two radio beams. That's it. One horizontal beam called the localizer tells you if you're left or right of the runway centerline. One angled beam called the glideslope tells you if you're above or below the ideal descent path. Your instruments show two needles — one moves left-right, one moves up-down. When both needles are centered, you're on path to the runway threshold.
The approach plate gives you the frequency. Tune it in your NAV radio. The needles come alive. Everything else is just managing the aircraft to keep those needles centered.
Before you intercept anything, you need three things configured. First, the ILS frequency tuned in NAV1 (some aircraft use NAV2 — check your panel). Second, the inbound course set on your HSI or OBS — this is the runway heading, and if you don't set it, the CDI will show unreliable information. Third, your approach speed calculated and stabilized. In my CRJ-200, that means flaps 20, gear up, roughly 180 knots on the initial approach segment.
Most botched ILS approaches fail at setup, not at flying. The frequency is wrong. The course isn't set. The aircraft is 40 knots too fast. Fix those three things and the approach practically flies itself.
ATC or your own planning puts you on a heading that will intercept the localizer from a 30-45 degree angle. You're flying toward the extended centerline at an angle, watching the localizer needle. When it starts moving from full deflection toward center, you're approaching the beam. Start your turn toward the runway heading before the needle centers — the beam narrows as you get closer, so if you wait until it's centered, you'll overshoot.
How much lead? Depends on your speed and the wind. At 180 knots with no wind, start turning about 5 degrees before the needle centers. With a crosswind pushing you through, start earlier. This is feel, not math. You develop it with practice.
Once established on the localizer, maintain your altitude until the glideslope needle starts coming down from full up deflection. The standard glideslope is 3 degrees — that translates to roughly 300 feet per minute descent for every 60 knots of groundspeed. At 140 knots groundspeed, expect about 700 fpm. At 180 knots, closer to 900 fpm.
When the glideslope needle centers, lower the gear (if not already), set final flaps, reduce power, and begin descending. The key insight: you control the glideslope with power, not with pitch. Pitch controls airspeed. Power controls descent rate. If you're below the glideslope, add power — don't pull the nose up. Pulling up bleeds airspeed, which makes everything worse.
Below 500 feet AGL, you should be stabilized: speed within 5 knots of target, descent rate steady, both needles within one dot of center. If any of those conditions aren't met, go around. Don't try to save a bad approach at low altitude. Real pilots don't, and neither should you.
At decision height — typically 200 feet AGL for a CAT I ILS — look up from the instruments. If you can see the runway environment (approach lights, threshold, touchdown zone), continue to land visually. If you can't, go around. Full power, positive rate, gear up, fly the published missed approach procedure.
That's it. Frequency, course, speed, intercept, capture, stabilize, decide. Every ILS approach in the world follows this sequence. Practice it in my Jetstream 32 with manual flight — no autopilot, just you and the needles. Once you can fly a hand-flown ILS in a turboprop in gusty crosswinds, you can fly one in anything.
Javier Rollon develops aircraft for JRollon Planes. Follow on Twitter.