Puzzling a/p weirdness in default 737???

[Thunderbird8]

I've been experiencing occasional problems with the a/p on the default 737 and would appreciate some help if possible.

I'm just getting into flying heavies and last night I was practising some short flights in the 737 from Cardiff to Filton using the ILS at Filton R09. All went well for the first four flights. I was resetting the flight each time back to Cardiff to practice.

The thing I did differently on the fifth flight was change the flap settings up a notch after engaging the a/p, then the aircraft climbed uncontrollably and would not respond to changing settings in the a/p window. I also noticed that the flight director switch had 'come on' by itself. Nothing would solve the situation except killing the a/p and hand flying. Re-engaging the a/p would cause the steep climb again.

Next, the opposite, I did not alter flap settings after take off as it was such a short flight anyway and after engaging the a/p it would not recognise that it was supposed to climb and therefore tried to dunk me in the Bristol Channel. Same solution as before, kill the a/p and hand-fly.

I think the FD had come on that time too. Is there a 'known' issue with the a/p or FD to watch out for, as it was really annoying to feel so pleased with myself after landing a heavy properly for the first time ever to then have an issue I could not resolve?

Before you ask, the a/p settings looked right each time, master switch on, alt switch on etc.

PS My default flight is actually with an add-on (SF260), should it be with a default aircraft?

[tigisfat]

I don't think the problem lies in your default save, nor have I ever seen your problem before. Most often, these kinds of wierd things are solved by the obvious we overlook. I say this because we've heard about all manners of bugs and problems here, and usually radical departures from controlled flight are our own fault.

I really wish I had a good explanation for you. The only thing I can do is fire up FSX and get to trying to reproduce the problem.

Are you sure your vertical speed and altitude windows are set correctly? a vertical speed in excess of 1,800 FPM in slow approach speeds can trigger violent nose up moments. Sometimes the autopilot asks for a whole mess of trim in a slow aircraft that doesn't respond quickly. When it does start responding, the autopilot may go too far nose up.

[Thunderbird8]

Hi

I know what you mean. I tried and tried (pausing the screen and checking and rechecking settings) and I could not see anything to account for it. Some salient points:

1. When it worked it worked perfectly
2. It did not go wrong often
3. The FD 'came on'
3. A change of flap setting set the problem off I think

Maybe my attitude or speed was wrong and the a/p just head a head-fit and decided to self-destruct!

[NikeHerk67]

I've been experiencing occasional problems with the a/p on the default 737 and would appreciate some help if possible.

I'm just getting into flying heavies and last night I was practising some short flights in the 737 from Cardiff to Filton using the ILS at Filton R09. All went well for the first four flights. I was resetting the flight each time back to Cardiff to practice.

The thing I did differently on the fifth flight was change the flap settings up a notch after engaging the a/p, then the aircraft climbed uncontrollably and would not respond to changing settings in the a/p window. I also noticed that the flight director switch had 'come on' by itself. Nothing would solve the situation except killing the a/p and hand flying. Re-engaging the a/p would cause the steep climb again.

Next, the opposite, I did not alter flap settings after take off as it was such a short flight anyway and after engaging the a/p it would not recognise that it was supposed to climb and therefore tried to dunk me in the Bristol Channel. Same solution as before, kill the a/p and hand-fly.

I think the FD had come on that time too. Is there a 'known' issue with the a/p or FD to watch out for, as it was really annoying to feel so pleased with myself after landing a heavy properly for the first time ever to then have an issue I could not resolve?

Before you ask, the a/p settings looked right each time, master switch on, alt switch on etc.

PS My default flight is actually with an add-on (SF260), should it be with a default aircraft?


Thunderbird8

Question: Did you access the localizer before the glide slope had come alive....as in the diamond shaped symbol being visible in vertical plain of the HSI?

In the AP/APR (approach mode) your aircraft will fly through the glide slope and in some cases even climb if you access the ILS before both localizer and glide slope are visible. As for the FD, I'm under the impression that it should be on, especially with the default aircraft, since the FD controls the autopilot in default aircraft. Not necessarily so in add-ons.

PS: There is a problem with the default 737 FD with needs fixed using the SDK, however I've never been able to do it because of the ambiguous directions in the FSX/SDK. I did a quick search and can't find the thread, but if you need me to I'll find it later. It doesn't affect the AP/APR mode when flying an ILS approach though. It has to do with hand flying using the FD.

[Thunderbird8]

Just had the autopilot lose 2000 feet in a turn on base to Singapore ILS, then dump me into the grass 400 feet or so short of the runway!

It is driving me insane!

[xxmikexx]

Thunderbird8,

Try deleting or renaming fs9.cfg and then let the sim build a new one, = known good. (Or fsx.cfg as the case may be.)

[Thunderbird8]

Will try.

It is driving me mad.

[NikeHerk67]

BTW your "default flight" should always be a default aircraft NEVER an addon.

[Thunderbird8]

Thanks, why is that?

[NikeHerk67]

To save a lot of typing check out this thread.
http://www.flightsim.com/vbfs/showthread.php?t=184561&highlight=Default+aircraft+setup

I'm guessing it's somehthing simple like your NAV/GPS switch is in GPS, when it has to be in the NAV mode. I know all the mistakes we can make because I've made them all MANY times. :)

[Thunderbird8]

Hi,

Believe me so have I, but Nav/GPs switch is in Nav, trust me guys, I have checked, rechecked and rechecked again, with the help of simmers, Vatsim controllers, and a r/w heavy pilot with whom I am lucky to be acquainted.

I'm beginning to wonder if it's a bug in the default 737 in FSX.

OK - let me give you a scenario specifically. Approaching 02L at Singapore. ALT 3000, SPD 180, clean config, ILS frequency dialled into NAV1 and everything else I need to do done.

Cleared to intercept localizer and as the aircraft turns onto the localizer heading (the ALT button is still lit as the GS has not been reached yet) the aircraft practically nosedives and I have to kick the AP off and recover manually else crash into the sea. Fuel was at about 25%.

Am I too slow? It is a power issue?

[NikeHerk67]

I don't think there's anything wrong with the default 737's in any version that would affect an ILS approach like that. Have you changed the default flight?

It sounds like you know what you're doing alright, however 180 is a bit slow for clean. It shouldn't nose dive toward the ground at that speed though, but you're starting to pitch-up too far and would leave yourself vulnerable to a windshear, in the real world, at that speed clean.

Stay clean until 200 knots, as you reduce speed to 190 add 5 degrees of flap, 170 about 15, at 160 about 25, at =<150 30 degrees. You can go the max of 45 degrees of flap with a speed of 135 to 140 depending on conditions.

Mike was right about reconfiging if you're sure you've tried everyting else to and including starting your default flight with a default aircraft.

We're going to get to the bottom of this before we're done. :)

[Thunderbird8]

Thanks again, we certainly will.

[alexm]

I just read through this thread. If I understand the original post, you are trying to engage AP without the FD. That makes no sense. Turn on the FD so the AP has some guidance. FD should be activated on the ground. Have your altitude and heading set as well.

.If you are using AT, make sure you have set an appropriate speed.

[NikeHerk67]

I just read through this thread. If I understand the original post, you are trying to engage AP without the FD. That makes no sense. Turn on the FD so the AP has some guidance. FD should be activated on the ground. Have your altitude and heading set as well.

.If you are using AT, make sure you have set an appropriate speed.

Hold on Hoss! :)

If you've read this thread all the way through there's a key item or two that you may have missed.

First of all, not since FS2000 has it been necessary for the FD to be ON for the autopilot to work. FS8, FS9, and FSX are all the same, it doesn't matter whether the FD is on or off. The reason why, I won't go into here since I've declared this the "Be nice and don't offend developers millennium." :)

Secondly in FS2000 the FD came on when the atuopilot was engaged whether it was turned on or not, which is exactly the symptom that Thunderbird8 is describing. This is now what's making me think he could possibly have an add-on aircraft that's been updated from an old FS2000 add-on.

[alexm]

Hold on Hoss! :)

If you've read this thread all the way through there's a key item or two that you may have missed.

Ahhh... ermmm... well, you see... awww, nuts! It's not the reading that's the problem, it's the retention :o

That and the fact that it's been quite a long time since I've flown the defaults. If anyone reading this could see me now, you'd see my foot being jammed in my mouth!

OK, so I'm flying the default 737 now trying to see if I can duplicate what's being reported. Will report back if I figure anything out.

[Thunderbird8]

Thanks, I have a couple of addons, but none with an FD (they are GA aircraft).

[NikeHerk67]

Ahhh... ermmm... well, you see... awww, nuts! It's not the reading that's the problem, it's the retention :o

That and the fact that it's been quite a long time since I've flown the defaults. If anyone reading this could see me now, you'd see my foot being jammed in my mouth!

OK, so I'm flying the default 737 now trying to see if I can duplicate what's being reported. Will report back if I figure anything out.

No worries hear Alex!, I know you're a very good source of info and can usually figure these things out. That and the fact that you're tops when it comes to helping others makes you just A OK in my book and a great asset to the community.

In other words get your foot out of your mouth and on the pedals. :D

Best Regards to ya,

[alexm]

Hey, T'bird8-

What altitude are ya flyin' at (I'm guessing 2500-3000 AGL)? Reason I ask is I'm trying to duplicate your scenario. Also, you mentioned another flight with a landing scenario. Are you aware the autopilot won't land the 737 for you, as it's not 'autoland' equipped? You must disengage the AP, as well as the AT, prior to touchdown.

So, is this a more or less random issue, or does it occur more during landing (or takeoff)?

Thanks.


Regards,

[Thunderbird8]

Hi

Thanks, it occurs pretty much randomly, the last few times were:

1. Ploughing me into the ground whilst on an ILS approach after the AP had already had some issues on the base leg approach and lost over 2000ft. I recovered from that but once it goes wrong it tends to keep going wrong.

2. Second, after take off and climb out to 1000FT AGL and engaging the AP to intercept the SID radial with an airspeed hold set at 200 KIAS, a very (very) sudden and steep climb through 6-7,000 with the ALT window set to 3000. Only way back was kill the AP and hand fly back down. The FD switch had come on 'on its own' that time.

3. The same scenario as this but with the AP to seemingly ignore the ALT setting and nose-down to the water.

3. I have a suspicion that it might be to do with power or flap settings 'cos that's all I can think of.

I know it is tempting to ask me if all the lights on the AP were on where they should be because pilot error is the cause of most things (I'm sure it is here too) but I'll be damned if I can see what is wrong. I have paused the sim before crashing and gone over the instrument panel like a hawk.

Tell you what, what button is it for a screenshot? I'll try and get it to do it again and take some shots of impending disaster and show them to you?

Thanks guys.

EDIT: As an aside to this, I was flying the Airbus (default) completely hands-off when I first started getting into heavies and on the approach to Filton R27 (before intercepting the localizer) the aircraft literally nosedived into the ground almost vertically from about 5000ft. Is it possible that there is some kind of file inside FSX that is corrupted?

It's very annoying and I am hesitant to start planning to enjoy some long flights in the heavies because I don't want an investment of several hours to be ruined by this issue.

EDIT 2: My default flight is currently with the SIAI Marchetti SF260, which is the RalAir addon. I am told it should not be?

[NikeHerk67]

Hi

EDIT 2: My default flight is currently with the SIAI Marchetti SF260, which is the RalAir addon. I am told it should not be?

Thunderbird8,

Use a default aircraft as the default flight. If you don't MSFS will not load properly.

You may use any default aircraft at any default airport and save it as "Make this the default flight."

There are several states when loading the config files that have to occur using the default aircraft that can't be accomplished using an addon.

This will satisfy the requirements of the simulator to load properly.

[Thunderbird8]

Hi

When you say default airport, do you mean one that has not been overlaid by an add-on? E.g. my home field is EGTG and I have UK Airfields Vol 1 by Gary Summons, so should I be starting FSX at a different field?

[NikeHerk67]

Hi

When you say default airport, do you mean one that has not been overlaid by an add-on? E.g. my home field is EGTG and I have UK Airfields Vol 1 by Gary Summons, so should I be starting FSX at a different field?

Any airport such as EGTG is fine. I didn't mean to say default airport, my mistake. If you have a scenery addon that's fine.It's not the location, it's the aircraft that is important.
Once you have loaded the default aircraft save it as the default flight.

Once FSX is loaded properly it will work properly. Once it's loaded you can always go to your addon aircraft and load it. Just one more step each time you load up FS, but that's just the way it is.

This should solve the problem, if not at least we'll be working from a proper FS loadup.

[Thunderbird8]

OK guys, in honour of your support to date I will try this tonight and report back.

Stand by...

[alexm]

I see there's been some discussion before I was able to come back. And yes, setting a proper default flight is an important checkpoint, so it's good to hear you'll be reporting back on the results.

The only other question I can think of is what joystick/yoke are you using?


Regards,

[kwash55]

Thunderbird8:
I had saved an ILS approach to chicago at about 44 miles out over the lake at 9000' IN the 737. I was first directed to descend to 2700' than turn to 230 then turn right to 290 to intercept the localizer for runway 32R...Once I turned to 290 I kicked off the AP and flew her in visually so I never really put the ILS approach with the Flight Director to the test. This last flight I looked up the ILS approach frequency on Airnav and cranked it in to the NAV radio 1, reset the flight to 44 miles out at 9000 and began my approach again. I recieved the exact same vectors from approach fully expecting the ILS to come alive shortly after turning to 290 ( set to NAV , FD on , AT on, AP on, APP on, IAS about 260 ) the ILS came alive but there was no response from the plane indicating an attempt to capture the glide path / localizer. I felt that the plane should have began a gradual turn to line up for 32R. Suddenly the ILS localizer swung to the far left and the plane immediately began a sharp descending turn in the opposite direction away from the airport !!!.
I kicked off the AP and recovered manually ( just in time I might add) . Now I have to figure out what I did wrong...Im a little confused as to whether the FD is suppose to nullify all the auto pilot settings once it captures. For instance : If the AP was set at 2700 ALT the FD in order to fly the glideslope would obviously have to overide that 2700 setting and the same for airspeed . But that doesnt explain the sudden turn AWAY from the airport????
I'm going to have to test this again

Kent

[kwash55]

Well I just completed a second ILS approach to chicago Runway 32R . Same scenerio , same vectors same results...A sharp turn away from the airport when the ILS display suddenly slid to the far LEFT on a staple heading of 290. I did change 2 things however. I set the CRS to 320 because I had totally ignored what I has set in it and I also kicked off the AP when the plane began its sudden left turn thinking that perhaps the flight director would now take over the ils approach once it became active. To Know avail!! I have in the past successfully intercepted the glide slope in the 737 on other flights but frankly not with any consistentcy.


Kent

[NikeHerk67]

Thunderbird8:
I had saved an ILS approach to chicago at about 44 miles out over the lake at 9000' IN the 737. I was first directed to descend to 2700' than turn to 230 then turn right to 290 to intercept the localizer for runway 32R...Once I turned to 290 I kicked off the AP and flew her in visually so I never really put the ILS approach with the Flight Director to the test. This last flight I looked up the ILS approach frequency on Airnav and cranked it in to the NAV radio 1, reset the flight to 44 miles out at 9000 and began my approach again. I recieved the exact same vectors from approach fully expecting the ILS to come alive shortly after turning to 290 ( set to NAV , FD on , AT on, AP on, APP on, IAS about 260 ) the ILS came alive but there was no response from the plane indicating an attempt to capture the glide path / localizer. I felt that the plane should have began a gradual turn to line up for 32R. Suddenly the ILS localizer swung to the far left and the plane immediately began a sharp descending turn in the opposite direction away from the airport !!!.
I kicked off the AP and recovered manually ( just in time I might add) . Now I have to figure out what I did wrong...Im a little confused as to whether the FD is suppose to nullify all the auto pilot settings once it captures. For instance : If the AP was set at 2700 ALT the FD in order to fly the glideslope would obviously have to overide that 2700 setting and the same for airspeed . But that doesnt explain the sudden turn AWAY from the airport????
I'm going to have to test this again

Kent

Kent,

An IAS of 260kts is much too fast to access an ILS.
First of all the maximum IAS at an elevation ASL is less than 10,000 feet is 250 kts.
When accessing an ILS the IAS should be about 200 kts.
Access the ILS somewhere less than 20nm from the RW.
Both the localizer and glide slope will be visiable on the HSI (PFD in the 737-800).
Access the localizer first making sure the aircraft is under the glide slope.
NAV 1 tuned into the proper frequency for the ILS RW.
Course set to proper RW heading.

Follow these guildlines and you'll never miss another ILS approach. :)

[bstolle]

I might add that the vertical indication of the FD in the 737 is screwed up.
A fix is posted somewhere in the flightsim forums.
Maybe that's also a reason?

[tigisfat]

I might add that the vertical indication of the FD in the 737 is screwed up.
A fix is posted somewhere in the flightsim forums.
Maybe that's also a reason?


Funny, I get good vertical indications but ZERO localizer or heading indications on the FD.

[bstolle]

That's exactly the point. There are no 'steering' commands.
But it's a simple fix. In the FD section radians and degrees have been mixed up.

Much more disturbing is the yaw and directional stability problem of the 737.
It took me nearly 2 days of fine tuning to get the 737 to behave like a real plane ;)

[NikeHerk67]

I might add that the vertical indication of the FD in the 737 is screwed up.
A fix is posted somewhere in the flightsim forums.
Maybe that's also a reason?

Bernt,

True, the FD in FSX isn't correct, however it does not affect the autopilot's ability to access an ILS, nor does it affect the autopilot at all. In fact, in all (post FS2000) versions of MSFS the autopilot works without the FD even being activiated. Only in FS2000 was it necessary to have the FD on when using the autopilot. MSFS hasn't gotten it right since FS2000. What I mean here is that, in FS2000, the autopilot slaved off of the FD like it should. It was the out-crys of the developers, that couldn't seem to grasp the concept, which, in turn, forced MS to change it. There, I said it. I'll probably get some static over it thought. :( This probably isn't the forum to discuss that anyway. :) We've already had that conversation in a greatly debated thread about the FD.

Just in case anyone wants it, here's the thread for fixing the FD.
http://www.flightsim.com/vbfs/showthread.php?t=159183&highlight=problem+FSX

After fixing the code you can properly access a preset HDG, VOR, or localizer when hand flying and using the FD depending on the mode....without the autopilot being engaged.
Without the fix the verticle (azimuth) bar on the FD doesn't work.

[Thunderbird8]

OK - update. Flew last night from Bristol to Spain and the AP behaved itself, or at least I behaved myself whilst controlling it. This is after resetting the default flight as recommended.

I will monitor the situation!

[NikeHerk67]

OK - update. Flew last night from Bristol to Spain and the AP behaved itself, or at least I behaved myself whilst controlling it. This is after resetting the default flight as recommended.

I will monitor the situation!

I'd assumed we'd given you enought evidence about the default aircraft long before you ended up changing it. :)

It's usually something simple like that. I realize there are those who want to immediately have you delete something, change the configuration, or even reload the program. In the military we had levels called "echelons," which was simply the proper steps for solving problems.
Example: If transportation had a jeep that wouldn't start, we wouldn't immediatly change the engine. We might begin by checking that there was fuel in the tank before even popping open the hood (or bonnet) you might say. :D

It's good to hear that that you changed it though.
Sounds like you've learned something, which is what counts here.

Good Luck, and have fun.

[Thunderbird8]

Hi

I'm not entirely convinced after one flight but, don't get me wrong, I'll be pleased if this does sort it out. I hate to say it but if memory serves the Marchetti is only a recent addition and I was having problems before that when my default aircraft was the C172.

But let's not detract from a good flight, I'll do another one soon and report back.