Approach using the APP mode in Autopilot

Pro Member Trainee
ortegren Trainee

I have a slight problem doing an ILS approach using the Autopilot. I normally do this manually (just for the fun of it Wink but I have tried a couple of times to use the APP mode of the Autopilot. What happens is that when I try to intercept the glideslope from below, I wait for the ILS needle to start moving before switching to APP mode. Everything seems fine and the aircraft starts pitching down. Then it seems like I end up above the glideslope and only the heading is adjusted. I drift further and further away from the glideslope without any action from the autopilot. I was using the standard B737 when trying this the last time. Anyone got any ideas? What am I doing wrong?

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Pro Member Trainee
Ohiosimmer Trainee

I had that problem before, try and switch from GPS to Nav before you press APP

Good luck

spuddi Guest

did you have the altitude hold still applied on the Autopilot?

Pro Member First Officer
michlin First Officer

Yes, you must have the NAV/GPS switch set to NAV. You also need the runway's ILS radio frequency punched into your NAV radio.

Take a look at Fire_Emblem_Master's ILS approach instructions here:

Pro Member Trainee
ortegren Trainee

Thanks for your suggestions but, yes, I have Nav mode and the altitude hold automatically releases when you press the APP button (at least in FS2004). I haven't done this many times, but I can definitely remember that I used to do this in earlier versions like FS2000. I get the same symptoms as if I had been above the glideslope when enabling the APP mode. It's just that I am below the glideslope at first and I can see a pitch down at first, but then it fails to hold the correct descent rate.

guest Guest

I had this problem too for a while, but i realized that the airport I was flying into only had localizer, no glideslope. Make sure you are flying into an airport with both.

Pro Member Trainee
ortegren Trainee

Yes, I have the correct ILS frequency. I can follow the ILS manually without the auto-pilot. Besides, if I didn't have the correct frequency, I wouldn't see the ILS needles moving...


Autothrottles engaged?

Pro Member Chief Captain
Alex (Fire_Emblem_Master) Chief Captain

Try having the APP button hit BEFORE the glideslope, or any localiser needles begin moving. It wont automatically disengage the alt hold, and, autothrottles don't have anyhting to do with it, except that it makes it easier for the aircraft to hold the G/S with them because you dont have to screw with the gas.

Also, make sure that you descend to your instructed altitude quickly, as in 22-2500FPM. that way, you are at a altitude where you can intercept the G/S for a longer period of time. And, to make matters easier, turn a little bit more toward the airport you are flying into, that way, you wont go too far away from the airport to intercept the G/S

Pro Member Captain
David (The-GPS-Kid) Captain

My view on why this is happening is that you are approaching too fast and as such your A/P system is losing track of the Glideslope (commonly known as "ungripping" .....

You didn't say what you're flying but in most planes if you fly too quickly you will loose your Glideslope capture.

Pro Member Trainee
ortegren Trainee

Thanks for all suggestions. The most probable explanation as I see it is that I have to high speed. I have been flying the standard 737 and I'm aiming at 165 knots waiting for the glideslope but probably been to late adjusting it down when intercepting the glideslope. I have been using autothrottles when trying this and just dropping the gears and extending flaps will increase the throttle setting if I'm not quick to adjust it. I will experiment a little.

Pro Member Captain
David (The-GPS-Kid) Captain


In the default 737, wind the speed down to 145, instead of 165 before your expecting to reach the Glideslope.. (Full FLAPS will help you to decelerate to this speed quickly and use the Autothrottles to keep you there)..... When you capture the Glideslope and start descending, wind down to 135 (approximate VAPP in this plane), gear down etc, and your landing will be easy at this nice steady controlled speed.

Good luck !

Pro Member Trainee
ortegren Trainee

Thanks. I will try that. When I fly manually, this comes more naturally since dropping gears and flaps when intercepting the glideslope automatically reduces speed...

PH Guest

I think GPS KID is probably most correct! Speed is key on the approach. Be stabilised above 1000-1500ft AGL which is about 3-5 miles out flap 30 or 40 speed at 135KIAS gear down. I always select flap 10 or 15 before the glideslope comes alive speed back to 160. Once the GS is a dot above centre gear down, flap 20 you will slow your ROD doing this and capture the GS. Once on the glide flap 30/40 bringing the speed back to 130-140 landing checks complete on "cleared to land" by ATC.
If you get into a routine like this wherever you fly it makes it easy not to forget what did I forget!! 😀

Pro Member Captain
David (The-GPS-Kid) Captain

You're right PH - I'm getting really into "Checklists" at the moment - I typed up a colour chart (at work.. tee hee), with some generic Checklists to use, for :-

- Taxi Checklist
- Take Off Checklist
- After Take Off Checklist
- Climb Checklist
- Descent Checklist
- Initial App Checklist
- Finals Checklist
- Landing Checklist
- Rollout Checklist

.... They're not hugely realistic by any means as real checklists are specific to the aircraft, but they remind me of the essentials, ie:-

Take Off Checklist

- Taxi Lights OFF
- Landing, Nav, Beacon Lights ON
- Flaps Set
- Elevator Trim Set
- AP Heading set to Runway Heading
- Initial A/P ALT as cleared, set
- A/T Speed set
- APU OFF (Where fitted)
- Parking Brake OFF
- Brakes ON (Until ready)

I'm sure I missed some but you get the idea - it takes 10 seconds to cast your eyes over to remind you done everything - and it's pretty much guaranteed to prevent any major mis-haps, such as trying to take off in a 747 with NO flaps set ! (Need a rather long Runway for that one).

If anyone is interested in increasing their knowledge of the procedural side of Airliner operation, a great way is to get some "Cockpit Flight DVDs" - I guess I'm a geek as I have 3 great DVDs (8 hours worth!)... you get to see everything that you know from FS, in the real world - I have the Dash 8 add-on from Just flight and I recently bought a FlyBE (UK airline) DVD featuring the Dash 8...... It was amazing how identical the cockpit was to the add-on ! Even down to the buttons on the AutoPilot, etc.

I have:

FlyBe (Dash 8, BAe 146, CRJ200), 3 hours
BWIA (A340, Dash 😎, 3 hours
Atlas Air (B747-200, B747-400), 2 hours

you realise how much is represented by FS2004 - you hear the same ATC stuff that you're used to on FS (and a lot of stuff you've never heard!).

I bought all of my DVDs from They are good value, fast worldwide delivery and always well stocked.

PH Guest

GPS-KID I will send some checklists over for the 757 and 737 when I get the disk back to send you if you like.

Pro Member Captain
David (The-GPS-Kid) Captain

That'd be fab, especially for the 737 as it's one of my key 'ratings'. (I'm not rated on the 757) 😂

... but as well as being useful for the 737, it would help to make the generic ones more accurate. (The standard FS ones are neither accurate nor that useful I find).

Cheers PH, much appreciated !

Pro Member Captain
David (The-GPS-Kid) Captain

.... PH sent me the Checklists, great stuff - my own are surprisingly accurate but now I have the V-Speeds, etc... Cheers P.

Pro Member Chief Captain
Alex (Fire_Emblem_Master) Chief Captain

I might add that while I never truly touched on the flap settings in my ILS explanation, from what I've been doing (According to Delta Virtual procedure) is doing my descent/early approach with little to no flaps, extending flaps incrementally during the descent to glide slope intercept altitude. This mantains a rather high speed, allowing for a shorter in flight time. I usually hit the G/S at 153KIAS in the 737-400. I haven't had any big mishaps since my nephew hit the spoilers and i had to figure out why i was going down so fast...

Pro Member Captain
David (The-GPS-Kid) Captain

It's funny you mentioned that FEM, cos I was watching my new (some say geeky) DVD last night of a A340 flight from London Heathow - Port of Spain, Trinidad, and the Pilots approached in the same way you've described above.

They didn't go to Flaps 2 until 1500 fet, Flaps 3 at 700 feet and Flaps Full at 600 feet. looks like you're pretty accurate in your timings for moving thru the flaps. I've been getting the aircraft config'd early for a good final, but looks like I need to try holding off a bit !

Pro Member Chief Captain
Alex (Fire_Emblem_Master) Chief Captain

Yeah, I used to do that too, maybe cause i was worried i'd come in too fast, but when you think about it, you burn less fuel "gliding" than you would with power on with flaps.

PH Guest

Depends on the airlines SOP's if you watch Ryanair a/c I think they land flapless! Taxi on full power and use the escape slides to disembark. In FS time and fuel are not major considerations but certainly if you want to add to the realism then play it the airline way. I think for learning and establishing a routine then route for a long final. Once you have the ability and confidence to cut the corner do so. On the last course I was on (757) we did some high speed approaches down to 3000ft at 290kts then base slowing while descending to 210kts, final app track (localiser) from 6 miles 180kts, then waiting until 4 miles until slowing to Vapp.
Also worth mentioning is the reluctance for some a/c to slow. The 757 is very slippery!

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