Localizer capture impossible

[alexven1972]

Dear support Team,

the localizer capture needs major fixing in my opinion.

i tried the standard ils rwy5 procedure at Comiso (LICB). I was coming from LICC (Cagliari), so the whole arrival procedure was in the FMS. LVCH and NAV were active and LAND mode was armed (LOC/GS blue). At 3000ft and 9miles from Comiso VOR the plane started the left standard turn (180kts speed selected) but when LOC* activated it didnt follow properly the purple diamond, wich passed the centerline and then stayed on the far left. Despite this, the FD did not command the required left turn to correct and remained in the center, with LOC* green and purple diamond on the far left side. GS was properly followed and the poor a310 crashed on the ground, 1 mile parallel to the right of the runway. 😂😂😂🫣

tried 3 times:  same resuts. If U want to try the above procedure, i think that u can reproduce the scenario.

it seem that the FD struggles in intercercepting the LOC, particularly when steep turns are needed and the purple diamond cross the midline rapidly.

Platform used : xbox series x. 

All the best

Alessandro

[Alexair]

Hmm, doesn't have this issue.

Did you try intercepting the LOC within a maximum of 30° angle ?

[alexven1972]

I agree.

with low intercept angles everything works fine, but nevertheless i think that the FD should try to chase the LOC purple diamond regardeless of the intercept angle and it does not happen: when the LOC intercept angle is steep, the purple diamond crosses the midline and the FD commands the correct turn for a while and then it stop chasing it.

The final picture is: FD centered on PFD with the purple diamond on the far left (or right) and LOC*/GS green. Tipically the aircraft at this point is parallel to the runway, on glide path. 

Therefore i think that the FD LOC capture logic of the a310 needs substantial refinement.

Alex

[JoshF]

The A310 does not feature the Enhanced LOC* found on more modern Airbuses. It actually had a quite a restrictive intercept angle, and we have modelled this in the sim. If you feel that even factoring that in that work needs to be done, please post a video if possible of a LOC capture that doesn't work, but you think it should 

[alexven1972]

it is difficult for me to post a video but U can try the approach i described above yourself (LICB ils RWY05). I tried 4 times from 4 different departing locations: same result. Believe in me when i say that the autopilot will try to capture the localizer but it will fail  and you ll find yourself on the right side of the runway on long final and if dont take over switching off the autopilot, the aircraft will crash. I hardly believe that the real A310 cant nail such a standard approach…….😋

all the best

Alex

 

[Alexair]

As JoshF said, there is a lot of aircraft in real world that cannot capture properly or even capture at all if you intercept LOC within 45° or even 30°.

I flew real life on those airplane and still fly on an airliner that cannot capture LOC above 30° and sometimes we have to "cheat" a little bit when some controlers give us more than the aircraft limitations. The A310 is no exception, if you remain within 30° the interception work just fine, maybe sometimes slightly off course when in strong crosswind component but nothing as you are describing.

[alexven1972]

ok, Watch this. It is another approach with the same problem i encountered : LOC* green, purple diamond on the left side, FD centered, GS captured.

it is not a matter of angle of interception. the FD is absolutely static and it doesn t chase the localizer. The pilot switch to CAT3 and finally takes over for a manual landing. The runway centerline stays on the left side during the whole approach until the pilot corrects manually. i m also a private pilot and i m sure that this autoland system would never obtain any kind of certification. I m convinced that the FD of this A310 has a BIG problem.

Other than this its a fantastic liner with immersive in depth systems🤙

have a nice evening😉

[Alexair]

Oh ok, I get your point now. I didn't clearly understood the problem initialy. Thought it was during initial LOC interception.

Yeah, it make sense now. Unfortunately I didn't get this problem so far, so I can't help you on this one.

Give it a try maybe on those airport : KCLT, KFLL, KBOS, LFPO, LFMN, EFRO

They are the one that I went and I didn't get your problem. Just to compare if you can get it done correctly on those airport or not.

The only advice I can give you now. Inibuild's guys will probably help you out better than me.

😉

[alexven1972]

 

Apparently the FD is somewhat “sluggish” and unable to recover the LOC diamond when it overshoot the centerline during the final turn (wich can happen with higher degrees of intercept like in the video above or in the LICB ilsRWY05 procedure tested by me). Not all the approaches in the world can cause this issue (maybe including those of the airports you mentioned?): with smaller intercept angles the LOC diamond WILL NOT oveshoot the center and the LOC capture will be probably easier.

But definetly a certified CAT3 autoland system (albeit older) has to recover an overshooted LOC diamond on a long final of an ILS procedure, don t U think so?😉

Hope that Inibuilds Team will consider this for a future fix!🤞

regards

Alex

[alexven1972]

so here is another example of the a310 FD “laziness”. The approach is again Comiso LICB ilsrwy05 (COM VOR transition). This time i wanted to help the FD a little, inserting manually 2 PBD points after COM-D9 in order to allow a smoother final left turn ending in a lower LOC intercept angle. After a WAY TOO LONG LOC* ,parallel to the localizer, at the end it nails the LOC green. This time, the “laziness” of the FD involved also the GS capture: as U can see, the GS diamond passes the midline but the FD does not command the descent until 1 dot below. At this point suddenly it commands a -5 degrees dive 😰In real life all of this could probably have triggered a go around. 🤔 

 

[parsec71]

Just experienced something similar while on approach to ESSA 01L. The aircraft captured the LOC but doesn't capture the glide slope when the diamond hits the center.

[Alexair]

Yes, I agree. On those 2 videos it is obivous that the A/P is little bit lazy correcting the ILS.

In the real life airliner I'm flying that can happened (even in CAT 2) when little bit away (12-15 nm DME), the A/P is struggling a bit to maintain LOC centered but that disappeared when around 10-8 nm out, at that point the A/P follow just perfectly the LOC/GS, even with some crosswind.

One suggestion though, in the last video you are little bit late configuring and slowing down the plane. in real life the 1000ft RA is the limit to be stabilized and configured for landing (stabilized in LOC/GS and Vapp SPEED ) and in my SOP it trigger the "1000" call by the PNF and the "STABLE" reply by the PF. Of course if not stable it trigger the go-around. In my SOP again (depend airline of course) we have one last trigger at 500ft RA where the PNF call "500, STABLE, TARGET, SINK xxx", mean that by no lower than 500ft the PF should be on LOC, GLIDE and at the targeted Vspeed and the PNF announce the sink rate. I'm not fying the A310 in real life but the principle is more or less the same (just a question of SOP). Just my 2 cents...

[alexven1972]

yes you re right. i was way too late in configuring it for landing😂😂😂😂😂

i was solely focused on my smartphone while shooting the video and i totally forgot to deploy the landing gear and full flaps🫣🫣🤪🤣🤣🤣🤣

 

[Alexair]

That's what I thought... 😅😂

[JoshF]

6 hours ago, alexven1972 said:

so here is another example of the a310 FD “laziness”. The approach is again Comiso LICB ilsrwy05 (COM VOR transition). This time i wanted to help the FD a little, inserting manually 2 PBD points after COM-D9 in order to allow a smoother final left turn ending in a lower LOC intercept angle. After a WAY TOO LONG LOC* ,parallel to the localizer, at the end it nails the LOC green. This time, the “laziness” of the FD involved also the GS capture: as U can see, the GS diamond passes the midline but the FD does not command the descent until 1 dot below. At this point suddenly it commands a -5 degrees dive 😰In real life all of this could probably have triggered a go around. 🤔 

 

A few things to try

 

Push LAND later. Use V/L first to establish fully on the localiser when the diamond is +/- 1  dot. 

You need to be LOC captured before it will descend on the G/S. It looks like in the video that the FDs don't command nose down until the G/S diamond is one below; but if you watch your FMAs at the same time, you can see that it actually descends when LOC* transitions to LOC. 

[alexven1972]

yes, i noticed that. Maybe the logic of the 310 needs LOC GREEN before GS GREEN (my hypotesis). Nevertheless i think that the clear laziness of the FD in transitioning from LOC* to LOC GREEN would have led to the same results, even if i d used VL for LOC capture and then LAND for GS. 🤔😊

[JoshF]

2 hours ago, alexven1972 said:

yes, i noticed that. Maybe the logic of the 310 needs LOC GREEN before GS GREEN (my hypotesis). Nevertheless i think that the clear laziness of the FD in transitioning from LOC* to LOC GREEN would have led to the same results, even if i d used VL for LOC capture and then LAND for GS. 🤔😊

Yes it probably would in that case if you armed it at the same time as you did LAND there, as the intercept angle was too sharp. Please try again with a shallower approach angle

[alexven1972]

ok tested the approach using V/L on the LICB ILS05 procedure, all programmed in the FMS.

Here is what happens step by step:

leaving COMISO VOR at 5000 started descending for 3000 at 180kts dct to COM-09. LVCH / NAV active. 1 mile before COM-09 leveled at 3000ft, speed down to 170kts, Flaps 20/20, Gear down. Flyover COM-09 on NAV, left turn on final mantaining 3000ft. While on turn armed V/L. The LOC diamond slowly comes in from the right, then LOC* green. At this point the 310 is on final, at D9 from runway treshold, centerline of runway being slightly on my right side,almost parallel to my heading. Here is were problems start: the LOC diamond comes in too slowly as the FD commands an intercept angle of no more than a pair of degrees. At D7 the GS diamond is at center but due to FD laziness in intercepting the localizer i m still in LOC*. 🤔Only thing that can be done to avoid a GO AROUND is to manually start the descent in V/S, chasing the GS until LOC green, then arm LAND to capture. 

It seem that 2 miles (from D9 to D7) are too short for the aircraft to intercept the localizer

have a nice evening👋

Alessandro