aircraft cant capture the localizer

[barty]

me neither, unless as already stated I'd forgotten to set the AP to the proper mode.

there are some (freeware addon) airports with disfunctional localisers or glideslopes, but nowhere I've ever seen in the default scenery.

The localizer itself works great, I can fly the beam all the way to the runway, but for whatever reason I couldn't get the AP to work properly. The time or two this has happened all I did was switch frequencies to the localizer frequency and switched the autopilot from nav hold to approach hold and it just went into a constant 30 degree bank and flew right through the localizer.

So guys, yes, it has happened. Why? I don't know. It has not been a regular occurrence.

[NikeHerk67]

The localizer itself works great, I can fly the beam all the way to the runway, but for whatever reason I couldn't get the AP to work properly. The time or two this has happened all I did was switch frequencies to the localizer frequency and switched the autopilot from nav hold to approach hold and it just went into a constant 30 degree bank and flew right through the localizer.

Hi barty

I'm not sure I understand what you're saying as some others here may be confused as well. That's no reason to just let it go at that. I'm sure if others were searching for an answer they would have reached a dead end here.
So.......... let's give it another go, if you don't mind.
What do you mean when you say autopilot in nav hold?
Do you mean NAV Mode. If so, the only time you should be in the autopilot NAV mode is when acquiring and tracking a VOR radial. Although the autopilot can acquire and/or track a localizer beam in the NAV mode, it would never be done, or should never be used for that purpose.

If you do indead mean the heading mode, let's just say you don't need to switch the autopilot from the heading mode to the approach mode. The autopilot will switch automatically once it has sensed (acquired) the localizer. And yes, the aircraft will turn toward the localizer beam and fly right through it, especially if you're flying at a speed of 200kts. or so from an angle of 30 to 45 degrees. The autopilot is not as responsive as if you were hand flying using the FD to smoothly turn onto and track the localizer following the FD command bars. However the autopilot will eventually line up the aircraft with the localizer on its own with a couple of small corrections along the way....to LOCK ON! That's a good thing and I'd bet it's the same in the real world unless all pilots hand fly the localizers. If it didn't overfly it smoothly, at those speeds angles, you might look back and see all the passengers on one side drenched from beverages that junped out of the carts. Not to mention a grouchy crew at the gate.

Note:
There is a problem with the FD in the 737-800 in FSX however. The heading bar simply doesn't work unless you fix it in the bgl files. There's a post showing that a line in the FD controls uses "radians" instead of "degrees" for the heading bar system. You can read about it here. http://www.flightsim.com/vbfs/sho...ht=problem+FSX
Once that's fixed, you can then hand fly the localizer beam without the autopilot engaged. Once one the localizer, engage the AP and you're good as gold.

There's one more item, which is worth noteing, at the risk of a mass confusion outbreak.
Although it is a part of the check lists, and the FD should always be ON, in FS8, FS9,and FSX it doesn't NEED to be ON for the autopilot to work. So, just think of the FD as slaving off the autopilot instead of the opposite when the autopilot is engaged. You can still use the FD to acquire a preselected heading and altitude, in the default aircraft that are working properly, when the autopilot is not engaged. So, it "IS" usable, which is what really counts.

As it's been said before, and I agree, I've flown ILS approaches without a hitch for the past 10 years, and unless I forgot to switch from the autopilot GPS mode to the atuopilot NAV mode never miss.

I hope that this helps shead some more light on the subject.

[RickCan]

seems the plane cannot capture the localizer during approach, what happen?

conditions

1.flying about 2,500-3,000 ft upon approach
2. AP is armed
3. ILS freq. has been tuned and set in NAV 1

am i too high during final? what is the recommended alt during approach?

You have to be below the glide slope indicator if the ILS of the runway has one. Don't forget to press the APPR button on the radio panel after line up for final. The autopilot should turn you to the runway heading.

I also prefer to set the CRS of the runway. eg Rwy 12 = 120 degrees. Rwy 21 = 210 etc.

[barty]

Hi barty

I'm not sure I understand what you're saying as some others here may be confused as well. That's no reason to just let it go at that. I'm sure if others were searching for an answer they would have reached a dead end here.
So.......... let's give it another go, if you don't mind.
What do you mean when you say autopilot in nav hold?
Do you mean NAV Mode. If so, the only time you should be in the autopilot NAV mode is when acquiring and tracking a VOR radial. Although the autopilot can acquire and/or track a localizer beam in the NAV mode, it would never be done, or should never be used for that purpose.

NAV Hold = NAV Mode. In the situation I was describing, I was flying a VOR radial to an IAF, then switched the radio to the localizer frequency, then switched the autopilot to approach hold. I've done it countless times before, but for whatever reason, it didn't work a couple of times. It would just go into the bank and circle when it should have captured the localizer (the needle was active, I had been monitoring it on NAV2).

FWIW, NAV hold can be used to track a localizer in a non-precision approach. It will just use more coarse course correction in this mode but if you're centered on the localizer anyway, it doesn't make any difference.

[NikeHerk67]

It would just go into the bank and circle when it should have captured the localizer (the needle was active, I had been monitoring it on NAV2).

I hope you won't be offended if I make joke.
I know this isn't the case in the FS, but if I were the pilot, I'd turn in a ticket on suspicion that the BC light was burned out.

FWIW, NAV hold can be used to track a localizer in a non-precision approach. It will just use more coarse course correction in this mode but if you're centered on the localizer anyway, it doesn't make any difference.

As I said before NAV hold could be used to track a localizer beam, but why would you when the autopilot APPR mode is more sensitive? I still can not visualize a scenario that would constitute switching directly from NAV hold to APPR. When I'm tracking a radial from another VOR to the localizer appraoch angle, as in a STAR approach for instance, once on course, I'd switch from NAV hold to HDG hold before acquiring it. I'm not sure this is exactly correct though, and am always anxious to learn something new. It's just the way I've always done it.
If I'm wrong it certainly won't be the first time and stand to be corrected

Regards

[barty]

Well, one occurance where using NAV hold could be used if you didn't want to use the glide slope. I guess if you were having issues with the trim servo and chose to fly the glide slope by hand while using the AP to keep you centered on the localizer.

Going from NAV to HDG to APR is correct if you don't want to disengage the autopilot while switching to the localizer frequency.

[NikeHerk67]

seems the plane cannot capture the localizer during approach, what happen?

conditions

1.flying about 2,500-3,000 ft upon approach
2. AP is armed
3. ILS freq. has been tuned and set in NAV 1

am i too high during final? what is the recommended alt during approach?

trazee,

First of all, thanks for initiating this thread. It's obviously attracted some great real world pilots, simulator pilots, developers, and experts. I'm probably the dumbest one in the smart row here so I'll recap what the experts have said.

Also, I apologize for getting involved with another question even though it was related, however from reading all the posts here, I hope this whole thread has answered your questions, as I've leaned from it too.

Here's the way I see it.

ReggieF5421 is right by asking for more details. Your altitude is OK if your somewhere between 15nm and 19nm from the RW when acquiring the localizer, which would put you UNDER the gldeslope.
RickCan, is 100% correct.
scott967, is right and it's a good idea to observe the common bars because they tell what's the autopilot is seeing before you see it actual reacts.
jwenting is right, because we've all been guilty of forgetting of get out of the GPS mode and wondering why the autopilot wasn't acquiring the localizer!
n4gix is right in that if we're having a problem accessing the localizer and glide slope (flying a full ILS approach), it's something we the pilots are doing wrong, not the FS.....
Kurtvw is right by suggesting that forgetting to switch the GPS/NAV to NAV will not allow the autopilot to acquire a localizer. And once again we don't know the distance from the airport you were flying to acquire the ILS.
barty has good points you can hand fly the approach using the flight director for most of the default aircraft, with the 737 being one exception until you fix the FD files.

They say you learn from you're mistakes. In that case I must have learned a lot through the years. Here are some things I've found to look for when flying an ILS approach and the aircraft just didn't seem to work right.

GPS/NAV switch: STILL in GPS probably the most common one.

Wrong frequency tuned into NAV1 active: Perhaps forgot to switch it from STBY side.

Wrong RW frequency programmed into NAV1 active: Instead on RW27R the opposite RW9L frequency was programmed in.

CRSE setting wrong: Forgot to set the course heading needle or (VOR 1 indicator heading in GA aircraft) to the RW heading.

BC Selected by mistake: Yes, by setting or hitting the back course button instead of choosing the APPR button will turn your aircraft 180 degrees from the RW and if someone could have made that mistake, it's yours truly.

Acquired the localizer BEFORE glide slope is was visible in HSI or BEFORE the horizontal needle one the VOR 1 indicator heading gauge deflected (above the horizontal line). This will allow you to access the localizer, however the aircraft will fly right through the GS and not deactivate the ELEVATION HOLD. I plead guilty once again.

Acquired the localizer above the glide slope: Do you know what the terms slipping an aircraft or making S turn approach to RW is or declaring missed approach? Some alternative I've picked up along the way.

Who am I you might ask? Good Question!
Perhaps the king of Undo, or the Officer in charge of RESET FLIGHT.

Enjoy,

[Brushstrokes]

Try STL runway 30L then.