MDA setting on approach cahrts?

[ryanbatc 13,184]

The key is the first number is the altitude you can descend to in ft MSL.

[mgh 89]

There is no decisionheight (DH).

There is. As already pointed out it's 209 ft.

[jeroen79 0]

Then I stand corrected. :)

[Great Ozzie 101]

This chart uses a missed approach point (MAP) which is defined as 7.5 nm after the final approach fix (FAF).

If you are flying the OAK ILS RWY 29 the MAP is at DH.If you are flying the OAK LOC RWY 29 the MAP is at the expiration of time (based on your speed).That is the only 2 ways of determining the MAP (in this case).Typically "we" teach to time from the FAF even when flying the ILS because if you lose the GS (becomes INOP... not because of your flightpath) you can revert to flying the LOC.Btw Steffen... the A/B/C/D... which is used is based on Vref at max certified landing weight. I think the 737NGX uses Category C (120-140kts).Also btw... the FAA Instrument Flying Handbook and Aeronautical Information Manual are two great references to use for your question(s).-Rob

[ryanbatc 13,184]

If you are flying the OAK LOC RWY 29 the MAP is at the expiration of time (based on your speed).

Why wouldn't it be based on .1 DME (MM) from OAK?I was under the impression you would be using DME unless your aircraft's is inop, in that case you would use a timed approach. ATC would tell you crossing MITOE and you'd start timing from there. Edited January 25, 2012 by ryanbatcund

[Great Ozzie 101]

Why wouldn't it be based on .1 DME (MM) from OAK?

Hi Ryan,The short answer is... that 0.1 distance is not a DME distance.The 0.1 distance is indicating the distance of the IM from the threshold. Pull up the KOAK ILS RWY29 (CAT II) approach chart and you will see the IM is use to indicate DH for an aircraft on the glidepath. (http://naco.faa.gov/.../00294I29C2.PDF)The only thing I see DME being used for (in terms of a fix) is identifying MITOE. That can be seen with that "bullet box" with the 8.8 and the Navaid ID. So the only way to i.d. the MAP is by time.If you would look at KDCA's LDA/DME RWY 19 Approach (http://naco.faa.gov/...00443LDAD19.PDF) there you will see DME (in this case off of I-VWH) being used for both the FAF and the MAP... including a stepdown fix (profile view). Bullet boxes with the mileage inside each one... and next to them the Navaid ID.-RobEdit: btw it is the other side of that 0.1 that is the localizer map... that left side line that lines up with the runway threshold.

[ryanbatc 13,184]

Interesting.

[FLEX1978 373]

There is. As already pointed out it's 209 ft.

Shall we confuse things some more? DH is 200ft DA altitude is 209ft. Important differance. DH uses the Radio altimeter, DA uses Barometric pressure.Regards

[Great Ozzie 101]

Interesting.

Yes! Very much so to me! And there is just so much to learn! Keeps one busy.

Well, there are a lot of numbers in the Minimums section but which one is the right one?

Steffen,Did all that make sense? Pick your category at the top... your approach type on the left... where those two intersect, that is what you use. In the case of the ILS for this approach, doesn't matter what category.If you are flying the LOC29 at OAK, say you are Category C... so your mins are MDA: 560'MSL and RVR of 5000'. The 551 is HAT (Height Above Touchdown... note TDZE of 9'). The stuff in parentheses you can ignore as that is for Military Pilots. Here's an FAA .pdf that will help too ("Legend and General Information") http://aeronav.faa.g.../frntmatter.pdf

[Great Ozzie 101]

DH uses the Radio altimeter, DA uses Barometric pressure.

Re: the DH for CATI approaches... not here in the U.S. - Most General Aviation aircraft that can fly an ILS won't have a RA. Although for CATII ILS approaches I would agree with that.That "200" will be HAT.