Nice, thank you all!
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Overall I think I understand why the categories keep confusing you. Youâre viewing them from the ILS angle of perception. Theyâre actually seen from a pilot/aircraft angle of perception.
Requirements with regards to ILS Cat I/II/IIIA and B are mostly indicators for different type of aircrafts that, despite the weather being not so inviting, carry equipment on board to still execute a safe approach. So even a heavy packed Cessna may approach a CAT III situation but can only offer CAT I equipment to the problem. ATC will now tell this aircraft to either sit it out or divert to a different field. While at the same time, the B744 coming in from Sao Paulo will just use itâs equipment with CATIIIB capabilities and put her right in the TDZ without too much questions asked.
Itâs more an aircraft rating than a procedure rating, so to say.
Makes sense! The flashing Cat II also threw me off when I thought I was doing a CAT IâŠbut as you said, I can just ignore that if the weather is good and set a DA.
Modern airliners will always select the highest procedures available to them. Most pilots only use it for aligning with the glide path anyway (as weâre lazy and enjoy auto trim) and disconnect at about 1000 AGL to put her down manually.
The equipment will always run down the same procedures and a CAT I capable autopilot will run the selftest and allow for about 10 seconds of deviations, on a CAT III it will only allow for 2 seconds. I wouldnât worry about all that in the sim as weâre not working with actual radio beams that can suffer from atmospheric signal contamination. But itâs cool to learn anyway, right? Makes for a great hobby too.
âWait⊠what are you doing, Step-Airplane?â
Caution Wake Turbulence
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Today I got another âtoo low, terrainâ message. I am pretty sure I was at the right slope, Iâm thinking I am landing too fast and maybe going in at too steep an angle, canât think of anything else that might be causing it other than an incorrect baro setting (maybe real world/simbriefâŠvatsim ect not synching with the sim?).
Another strange thing was that it said the outside temp was like 37 degrees at FL 32,000.
Any suggestionsâŠfor what is causing too low terrainâŠI think my speed was about 145 at 1000 when I disengaged the auto but had to align a bit at the end and didnt see the final speed.
Also I think the auto pilot managed speed wanted the touchdown to be 120 IFCâŠdoes that sound like a good target?
The âtoo low, terrainâ aural is a âsoftâ warning and itâs a caution about unsafe terrain clearance.
Iâm too lazy to find out what exactly trigger it. Most likely e.g. a too high speed and/or rate of descent at low altitude.
If itâs on the ILS with gear down and flaps extended it sounds like a bug to me.
What means IFC? The managed speed is the approach speed, not the touchdown speed.
An approach speed of 120kts is correct, but the weight must be very low in this case, ~50t.
Sorry meant to say IRC (if I recall correctly). The plane was set up for the default setup weight but was kind of strange and ran through gas really quickly so maybe it was under-loaded.
ok Iâm guessing I was too fast and triggering that if the approach speed was 120 and I was at 145 and landed somewhere around there. I was thinking 120 was really slow so I was pretty hesitant to approach at that speed.
What should the difference between touchdown and approach be.? If I understand it correctly, I maintain the approach speed until I hear âretardâ then go idle and flare up? Is there a specific speed I should look for like -20 from approach?
145kts wouldnât trigger a terrain caution.
E.g. in flap failure cases the approach speed can get close to 200kts.
Again, once on the ILS, there shouldnât be any terrain warning.
With flaps full a very good way to find out if you are too slow or too fast is the pitch attitude on a standard 3° GS.
If the speed is correct it will be ~ +2°. If itâs 0deg you are too fast and if itâs +5° you are too slow.
The touchdown speed depends a lot on your flare technique as well.
Some pilot touchdown almost at the same speed they had on final and some at Vref -15kts.
I think the warning came right after I disengaged the AP but dont think anything dramatically changedâŠwas at about 140 and on the glidescope though a bit to the right for part of it.
Also, I think the runway white and red lights were saying I was too low while the LS said I was perfect now that I think about it.
Sounds a lot like a bug to me and AFAIR in landing configuration there shouldnât be any terrain warning.
Maybe a stupid question, but are you sure that itâs âtoo low terrainâ and not âsink rateâ or âglide slopeâ?
It was too low terrain. I was going in to LAX.
Which runway? A terrain warning at LAX on the ILS doesnât make sense.
Which version of the FBW A320 are you using?
Developmental I believe from their website rather than from the market.
Iâve downloaded the installer from their website and use the development version. It gets updated almost daily and runs pretty stable most of the time. Maybe you can try that version instead of the experimental one and see if you can land without warnings. Like PZL says, it starts to sound like a bug based on your description.
Isnât âcaution terrainâ the soft variant? Or does the Airbus not come with that one?