Simple ILS Approach

Hi everyone,

Quick question. If I set up a trip between 2 airports with an ILS approach at my destination in the A320, what would happen if I didn’t fill out any of the approach page info on the computer, such as QNH, Temperature and Wind speed/direction?

Let’s assume I get on the GS with no issues, with AP on and im on finals. Without the above information input in the computer, would I be way off centre line?



Nothing. Once it locks on to the slope it is usually fine.

The PERF page is used to calculate how much airspeed that the airplane should use when doing the approach (which in turns tells the engine how much thrust it needs to apply or reduce). It calculates the current weight, plus the barometric pressure, temperature, and wind direction and speed.

Generally, if there’s a strong headwind, then the aircraft will calculate a higher approach speed because the airspeed sensor would be registering a higher value than the actual ground speed. So it needs to take that into account to the VLS and VApp calculation.

Without it, then the aircraft would probably approach the runway at less-than-ideal conditions (it could be too fast, or too slow). But as far as the Localiser and Glideslope is concerned, it has nothing to do with it, and it would still capture and follow the signal down to the runway.

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To be honest I’m not sure if the perf page even works on the default A320. I’ve put different winds and bogus qnh readings in there and it seems to have no bearing on approach speed. I’ve had no problem flying ILS approaches without putting any values in there and it seems to always approach at 140kts. Correct me if I’m wrong. Put a 50 mile head wind in there and see what you get

Well, I guess… I don’t know. I haven’t flown the default A320 since last year.

QNH and temperature don’t affect the approach speed.
Wind most likely doesn’t have an effect in MSFS either, because I’m pretty sure that the complex
ground speed mini function isn’t simulated.

That’s the Airbus philosophy and you will not find this in a Boeing.
I’ve actually saw an A330 touching down well before the threshold in the grass while trying to perform a go-around, because the ground speed mini function does have its limitations and drawbacks.

Of course not speed but you would think it would affect the ILS indicators otherwise why have them in there.

It doesn’t affect the LOC and GS either, but both affect the GS intercept altitude.

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