Hi,Recently on a LAX-LHR flight, I found that the DH/DA function wasn't doing what I thought it would have done.EGLL's airport elevation according to my charts is 83 feet. So I set 80 feet in the FP page of FS2Crew..On the page where the DH/DA is asked (approach briefing I think?) I set it to 200. D/H is decision height, and D/A... decision altitude? I don't know what the difference is if there is one.Anyway, on this flight the weather was good and I usually use 200 as a D/H in good weather so that's what I did (on the AB page and on the PFD).I monitored when the F/O called 300 above. He did not call at 500 feet AGL (200+300) which was odd. He called at 500 feet on the pressure altimeter, which means he made all of his calls 83 feet too low.Am-I supposed to set the DH/DA on the AB page to my DH + the airport elevation, or do I just not understand what a D/A is?Thanks!

Hi Phil,DA is based off the barometric altimeter, whereas DH is based off the radar altimeter, and for a CAT I ILS "DA" is usually 200 feet above the runway touchdown zone.So in the FP page you would set DA as shown on the chart for a typical CAT I approach. So if you're landing in Colorado or something, your DA will be a very high number.Cheers,

Hi Phil,DA is based off the barometric altimeter, whereas DH is based off the radar altimeter, and for a CAT I ILS "DA" is usually 200 feet above the runway touchdown zone.So in the FP page you would set DA as shown on the chart for a typical CAT I approach. So if you're landing in Colorado or something, your DA will be a very high number.Cheers,

Oh ok. I didn't realize that DA was on the approach plate, I always thought it was a pilot's discretion. Thank you!

Hi again Bryan,Maybe you can help me with this.Take a look at this CAT 2 approach plate: http://www.naco.faa.gov/d-tpp/0913/00237I25LC2.PDFI see on the bottom, next to S-ILS 25L, it says RA 204/12 100 (no idea what that is) and then DA 114Is this the decision altitude to set into the AB window of FS2Crew?Also take a look at this one: http://www.naco.faa.gov/d-tpp/0913/00237IL24L.PDFIt doesn't have a D/A.. It says next to S-ILS 24L 321/24 200 (200-1/2)200 would be the DH? So in this case I would want to enter 326 into the AB page I think, LAX elevation is 126 feet. Is this the right thing?Cheers,

Hi,On the ILS or Loc 24L approach, DA is 321 feet. So you'd enter 320 (or the closest rounded number) in the FS2Crew AB page.On the CATII approach, DH is 114 feet. There's a ton of info on the net on how to read these charts. I might suggest reading what's out there. I'm a horrible teacher <g>Cheers,

Hi,On the ILS or Loc 24L approach, DA is 321 feet. So you'd enter 320 (or the closest rounded number) in the FS2Crew AB page.On the CATII approach, DH is 114 feet. There's a ton of info on the net on how to read these charts. I might suggest reading what's out there. I'm a horrible teacher <g>Cheers,

Hi, thanks for the answer! I think I understand better now.I'll check out some navigation guides.Cheers,