Help with ILS approach

[toonman]

Hi everyone.

It almost always seems that when I am doing an ils approach with atc that the plane always seems to be off course by a bit..either too much right or too much left. I cant figure it out..I have the course etc set correctly. COuld someone please help??

Cheers

Joe

[WMFC235]

Sure I can try. But first I need to know what your aksing more precisly.


Do you mean that ATC gives you vectors that don't interecept the ILS localizer? Or are you just having trouble tracking the course after interception?

[toonman]

the vectors I am given are correct. I do intercept the ILS, but I find the plane just corrects its course and never gets a straight run. Sorry for not using the lingo. ATC will tell me to turn a certain heading and intercept the ILS. I do so and put the ole APR on with my course set correctly. The APR does its magic and the plane turns to head onto the correct course for the runway but it just never seems to get it there..always a bit out...etc..hope that helps


thanks

[Kerosene31]

What plane(s) does this happen with? Just one? Many? What is your approach speed and configuration?

Make sure when you intercept the ILS, that you manually turn to where you are within 30 degrees of the ILS path. If you are at too high of an angle, the autopilot won't always properly grab it.

[drumex]

Try flying manually. :-roll

I never use AP on approach, but once I tried and it flew the ILS just like you said.

Some say APP works perfect for them, some say it beheaves like you said. Don't know what they might be doing differently.

[slarente]

Couldn't it be that the localizer is not situated exactly where it should be at the airport? The plane would follow it properly, but still miss the runway...

[toonman]

its with all the planes for the most part.. example...default 737..heading in the direction that ATC gives at the altitude ATC gives and say travelling at around 230...APP engages...but just never gets a straight line in...always over steering so to speak

[Kerosene31]

Sounds like you are coming in way too fast. You should be down to maybe 180-190 knots from far out, then down to landing speeds a few miles out. I have no idea what the landing speeds are for the default, but my guess would be around 130-140. I'm sure someone can give better numbers, all I fly anymore is the PMDG 737 :)

[WMFC235]

The Approach button on the autopilot does not do a very good job correcting for crosswind. However I would not reccommend hand flying and ILS approach unless you have loads of IFR time. This is one of the most critical phases of flight, and extrordinarily more sensitive than any VOR. CAT II and III ILS(basically they can land without ever seeing the runway) certified pilots are required to fly these apporaches with both autopilots engaged and must take recurrent training frequently. Airline regulations for ILS approaches also require autopilot. I believe it was the 727 that had a rash of accidents a couple decades back because the captains thought they could fly the approach better that AP.

Go ahead and keep using the autopilot and just accept the variation, unless the needle goes beyond a full deflection which I don't think you said was the case). Also, don't let anyone tell you that you are more of a "person"(polital correctness at it's best) if you can hand fly an ILS to minimums without missing a beat(not that I think anyone on this board would say that, but if you fly long enough, someone will tell you this). This is just a dangerous approach to flying. The goal is to reduce your workload so that you can be thinking further ahead of the plane, and you should use any moral/ethical/and legal means of accomplishing this.

Great. now I'm back up on my Soap Box... Oh well. Have fun. See you in the air.

BTW, if you want to see a CAT IIIC ILS check out the plate for ILS Rwy 14R. And don't worry about using the "lingo". It will come in time if you want it to.

Steve@danhof.net

[WMFC235]

Good one. I never even considered approach speed.

usually apporach speeds are 110-120% stall speed with 10-15 degree flaps, gear down. As far as finding the stall speed, take the plane up to altitude get it in the landing configuration (full flaps, gear down) and just keep on reducing the throttle till it stalls. Incidentally, this is also close to the landing speed. Just add a little speed so you can flare and grease the tires instead of slamming into the pavement.