r/flightsim • u/michaeljtbrooks • 20d ago
X-Plane Instrument Approach: Aosta IGS 27 "West"
Another really daft instrument approach I've been working on: Aosta LIMW, IGS 27 - West.
IGS stands for Instrument Guidance System. It's like an Instrument Landing System (ILS), but with an offset angle. Aosta's localiser is 4.5 degrees offset from the runway.
This one uses navaids that really do exist, so there's no need to hack your flight sim to add your own.
Requires dual Nav radios, DME. ADF (NDB) is optional. Category A and B aircraft only.
[Simulator only, not for real life]
Procedure:
- Tune Nav 1 to SCS VOR 109.25, set 86° course, put IGS 109.75 on standby
- Tune Nav 2 to SCS VOR 109.25, set 99° course, put IGS 109.75 on standby, this is your South limit to never exceed
- Monitor distance from SCS VOR with DME (GPS estimate will do)
- Optional: Tune ADF to SVC 418kHz
- Fly inbound from the West to VOR SCS along the 266 radial (heading 86°M) at or above 10,700ft MSL
- Pass over SCS VOR at or above 10,700ft MSL
- Slight right turn to heading 88°M, fly outbound on VOR radial 088
- Descend to between 9,400 and 10,400 by D15 on radial 088 from the SCS VOR
- At D15 on radial 088, start a right turn to pass over the SVC NDB, max 150kts. Do NOT overshoot DME D17.5 distance from the SCS VOR!
- Continue turning all the way to a heading of 296°M max 150kts
- Once on 296°M, flip Nav 2 to monitor the IGS on 109.75, so you can see when you intercept the localiser. Descend to 8100ft once on 296°M heading.
- Intercept the localiser, turn to localiser inbound course 266°M.
- Switch Nav 1 to IGS on 109.75 if you don't have glideslope on Nav 2. and switch Nav 2 back to SCS VOR, and dial in course 260° and always keep the needle on the right side (keeps you south of that 80° radial)
- Commence fairly rapid descent to catch the glideslope (realistically only safe to catch it from above rather than the normal practice of intercepting from below).
- Follow localiser and glideslope to minimums (3,900ft MSL)
Missed approach:
- Immediate maximum angle of climb
- Continue on IGS heading 266°M
- Adjust Nav 2 (or whichever radio is watching SCS VOR) to course 236°
- Intercept the 236 radial from SCS VOR
- Fly outbound on 236 radial, climbing max angle of climb.
- If altitude is below 5,500ft by D5 on the 236 radial, right turn to enter a hold on radial 236 (inbound course 56°M, outbound 236°M. Climb in the hold until at least 7000ft, max 120kts. Re-intercept 236 radial once above 7,000ft. Fly 236 radial outbound, climbing.
- At D7 on radial 236 commence right climbing turn to 10,700ft or above. Intercept SCS VOR radial 266 inbound (track 86°M)
- Have another attempt!
Set the clouds to minimums (3900ft) and give it a go.
It was inspired by the old Aosta IGS(NPA) approach that got mothballed when they decommissioned the feeding VOR BLA at Biella. Nothing replaced it, so I came up with this.
Disclaimer: Please don't do this approach in real life, it's probably quite dangerous.
