Missed Approach Point

[Sabre-TLA]

I've searched the forums without success so posting this thread.

 

In the manual it says:

 

"Missed Approach. If during the final approach it appears you cannot safely land by the time you reach the Missed Approach Point (MAP), the approach must be aborted, close the speed brakes, raise the landing gear, set flaps to UP, and increase airspeed to 200 - 220 KIAS".

 

According to Wikipedia: "The missed approach point is published in the approach plates and contains instructions for missed approach procedures to be executed at this point. The missed approach point is normally at the Minimum Descent Altitude (MDA), and may be less than a mile from the runway or several miles out, depending on the conditions related to that particular runway."

 

I have never really worried about this flying sims before but I want to step up my realism as well and this sim is extremely realistic.

 

Will we get approach plates with instructions for missed approach procedures?

 

Thanks.

[Avilator]

Given that DCS does not model civilian air traffic, I personally think that chances of getting missed approach procedures are slim.

 

Also, it is most common for a category 1 ILS to have a missed approach point/minimum descent altitude somewhere around 300 feet AGL. I would set my altitude alerter to that altitude for starters.

[Dethmagnetic]

I've searched the forums without success so posting this thread.

 

In the manual it says:

 

"Missed Approach. If during the final approach it appears you cannot safely land by the time you reach the Missed Approach Point (MAP), the approach must be aborted, close the speed brakes, raise the landing gear, set flaps to UP, and increase airspeed to 200 - 220 KIAS".

 

According to Wikipedia: "The missed approach point is published in the approach plates and contains instructions for missed approach procedures to be executed at this point. The missed approach point is normally at the Minimum Descent Altitude (MDA), and may be less than a mile from the runway or several miles out, depending on the conditions related to that particular runway."

 

I have never really worried about this flying sims before but I want to step up my realism as well and this sim is extremely realistic.

 

Will we get approach plates with instructions for missed approach procedures?

 

Thanks.

 

The MAP is intended for approaches done by instruments, where you can't see the runway due to clouds or fog. If you get to the MAP and you still don't have the runway in sight, legally you have to do a missed approach. Like Wikipedia says, it depends on the airport layout and the type of approach. Non-precision approaches (without vertical guidance, like TACAN approaches) usually use a DME distance or a specific time period from the final approach point. Precision approaches (with vertical guidance, like ILS) usually use a specific altitude to go around at as you're descending. In either case, the only criteria for going around at the MAP is whether or not you have the runway (or the approach lighting) in sight.

 

Making the decision to go around due to a bad/sloppy approach is more of a judgment call, and doesn't really have a fixed point where you need to make a decision... I was always taught to go around at 200 feet AGL if I didn't have a stabilized approach, but you can definitely go around earlier (or later) if things aren't looking good. It just depends on the conditions and how comfortable you are with the airplane and your skills.

 

As far as approach plates go, I doubt they will be included with DCS, but you could probably find them online (you can get US plates at this site, although I'm not sure where to get Georgian/Russian plates).

Edited November 21, 2010 by Dethmagnetic
typo

[ESzczesniak]

Missed approach point applies only for non-precision instrument approaches. A MAP is a minimum altitude (reported in MSL) you may descend too before initiating a missed approach.

 

This is applicable for the majority of aiports in DCS A-10C. A place to find many real world charts is http://usa-w.vatsim.net/charts/. This is a resource for online FSX pilots (which I partake in quite a bit). I don't know the ICAO identifiers for airports in DCS A-10C to point more specifically.

 

Airports with ILS have a different set of minimums. Depending on the category of ILS (or TACAN-all precision instrument approaches) approach, you may descend to a minimum altidue (reported in AFE) before aborting your approach. This altitude is referred to as a decision height (DH) and unlike a MAP which is specific to an airport, DH is common to all runways with an ILS of a certain category.

 

In brief (reported for FAA regulations, also reported in meters for use in ICAO countries by some sources):

 

CAT I ILS: minimum 2 SM visibility and DH of 200' AFE

 

CAT II ILS: minimum 1/2 SM visibility and DH of 100' AFE

 

CAT III ILS: divided in to CAT III A/B/C with C taking you down to 0 SM visibility and DH of 0' AFE. If a CAT III X ILS approach is in use, visibility is no longer reported in statute miles (SM), but in runway visual range (RVR).

 

Also note that this is specific to the runway at an airport. Airports with multiple runways can have on with a CAT III/C ILS approach and the reciprocal runway with a non-precicions instrument approach.

 

Missed approach procedures are specific to the ruwnay/approach. In general though, they have a climb to 1,000-1,500' AFE on runway heading followed by a turn to a local holding pattern. These are sometimes modified for terrain avoidance.

Edited November 21, 2010 by ESzczesniak

[Tango]

Hi,

 

If you are on a visual approach, as would be the case the majority of the time in DCS:W, there are no minimums - just your judgment.

 

If you really screw up, you'll have a smoking hole. ;)

 

Best regards,

Tango.

[BlueRidgeDx]

A MAP is a minimum altitude (reported in MSL) you may descend too before initiating a missed approach.

 

Decision Altitude (DA) is specified in MSL, and is associated with CAT I precision approaches.

 

Decision Height (DH) is specified in AGL, and is associated with CAT II/III approaches.

 

Minimum Descent Altitude (MDA) is specified in MSL, is associated with non-precision approaches (like TACAN), and is to be flown until reaching the MAP which is specified either by a DME fix, crossing radial, timing, etc.

 

Airports with ILS have a different set of minimums. Depending on the category of ILS (or TACAN-all precision instrument approaches) approach, you may descend to a minimum altidue (reported in AFE) before aborting your approach. This altitude is referred to as a decision height (DH) and unlike a MAP which is specific to an airport, DH is common to all runways with an ILS of a certain category.

 

TACAN is actually a non-precision approach.

 

As above, the most common type of approach - the Category I ILS - specifies a DA which is expressed in MSL. Only a few certain types of approaches - Category II and III ILS - specify a DH expressed in AGL. (I'm purposely leaving out GLS, MLS, WAAS, etc...)

 

MAPs are not specific to an airport, they are specific to a particular approach to a particular runway. A given runway may have multiple types of approaches, for instance:

 

Runway 23R at Wright-Patterson AFB has 3 unique ILS approaches (plus a LOC-only variation), an RNAV GPS approach, and two unique TACAN approaches.

 

The MAP can be completely different for each of the non-precision approaches. Using my example, the MAP for the GPS approach is 1.6nm from the threshold at 1380ft MSL, while the TACAN MAP is 2.1nm away at 1320ft MSL.

 

Finally, DA(H) is not common across the entire category of approach. The ABSOLUTE minima are, but ACTUAL minima for each approach to each runway is determined based upon local factors. See below:

 

In brief (reported for FAA regulations, also reported in meters for use in ICAO countries by some sources):

 

CAT I ILS: minimum 2 SM visibility and DH of 200' AFE

 

CAT I approaches generally have a 200ft DA, and require 1/2SM visibility. Alternatively, RVR can be substituted for visibility if available, with a minimum value of 1,800ft.

 

Some CAT I approaches have higher minima than 200-1/2 due to considerations such as rising terrain, non-standard lighting, non-standard markings, etc.

 

A few very special CAT I approaches have lower than standard minima (150ft DA, and 1400ft RVR), but those require additional siting requirements, are designated SAACR approaches, and require the use of a Flight Director down to DA.

 

CAT II ILS: minimum 1/2 SM visibility and DH of 100' AFE

 

CAT II approaches have a Decision Height not lower than 100ft, and a required RVR of not less than 1000ft.

 

Minima may be higher depending on available ground equipment, lighting, obstacles, etc.

 

CAT III ILS: divided in to CAT III A/B/C with C taking you down to 0 SM visibility and DH of 0' AFE. If a CAT III X ILS approach is in use, visibility is no longer reported in statute miles (SM), but in runway visual range (RVR).

 

CAT IIIa minimum is RVR 700ft, and depending on aircraft capability, a DH may be required and will be not less than 50ft.

 

CAT IIIb minimum is RVR 150ft, and depending on aircraft capability, a DH may be required and will not be less than 50ft.

 

CAT IIIc is not currently used.

 

Again, these are the absolute minimum numbers...all of them can be adjusted upward depending on numerous factors.

Edited November 21, 2010 by BlueRidgeDx

[Druid_]

CAT IIIb minimum is RVR 150ft, and depending on aircraft capability, a DH may be required and will not be less than 50ft.

QUOTE]

Nope, possibly a typo on your part. CAT IIIb's are used by airlines routinely with 150ft RVR with no (zero) DH. The first you know about it is when the wheels hit the tarmac.

[ESzczesniak]

BlueRidgeDx, thanks for correcting my sloppy use of terminology. In particular, I had been using MAP instead of MDA in my post. At some point maybe I'll actually proof read posts rather than just spewing words on to the screen.

[Sabre-TLA]

Thanks for the detailed feedback.

 

So if assume CAT I ILS: minimum 2 SM visibility and DH of 200' AFE

for most of my landings I should be ok.

 

I'll check out the plate links provided but as Tango said, in most cases my judgment will have to do.

 

Hope I don't create too many smoking holes ;-)

 

Thanks everyone.

 

Attached is a RAR of all the Nellis approach plates to include in your kneeboard if you use one.

Copy of NELLIS Approach Plates.rar

Edited November 21, 2010 by Sabre-TLA

[BlueRidgeDx]

Nope, possibly a typo on your part. CAT IIIb's are used by airlines routinely with 150ft RVR with no (zero) DH. The first you know about it is when the wheels hit the tarmac.

 

Hey Druid,

 

I don't see the typo?

 

Yep, CAT IIIB lowest mins are 150ft RVR and no DH. You're right, there are many airplanes out there certified to fly approaches to those mins. But to use the no DH option, the airplane must possess a fail-operational autoland system. (I'm also leaving out the Alert Height (AH) discussion, because I've never dealt with its application in the real world.)

 

Anyway, for airplanes with a fail-passive system, a DH is required and must be no lower 50ft. To the best of my knowledge - and I can certainly be wrong - if a fail-passive system is used for CAT IIIb operations, the minimum RVR is 600ft unless there are special aircraft provisions to facilitate rollout.

 

To get lower than 600ft RVR, you have to have an approved rollout guidance system such as an autopilot approved for rollout guidance, or a HUD.

 

In the end, most of this stuff will be operator and airframe specific. To get to the lowest approved mins, the operator has to undergo lengthy Operational Suitability Demonstrations that can require hundreds of successful approaches/landings, gradually stepping down the mins listed in the OP SPECS.

 

Thanks for the detailed feedback.

 

So if assume CAT I ILS: minimum 2 SM visibility and DH of 200' AFE

for most of my landings I should be ok.

 

Double check those numbers, Sabre. The A-10 is Approach Category 'D', and the approach in question is the Straight-In ILS - labeled S-ILS 21L on the plate.

 

A quick look at the Nellis approach plates reveal that the ILS approach to runway 21L has approach mins of 200ft and 1/2SM visibility (or 2400ft RVR). DCS doesn't report RVR, so you would use visibility instead.

 

Fly the localizer and glideslope until you reach a barometric altitude of 2066ft (which is equivalent to 200ft radar height), and if you can't see the approach lights, go around.

 

If you see the approach lights, you may continue down to 100ft AGL (or 1966ft MSL) at which time you must be able to see the runway environment, which is defined as the runway pavement, runway lights, runway markings, or the red "terminating bar" of the ALSF-1 approach lighting system. If you see any of those things, you can continue visually to land. If not, go around.

 

There's a gotcha in DCS with the ALSF-1 at Nellis: They're presently located 1,000ft from where they should be, so don't use the red lights as a reference.

 

 

BlueRidgeDx, thanks for correcting my sloppy use of terminology. In particular, I had been using MAP instead of MDA in my post. At some point maybe I'll actually proof read posts rather than just spewing words on to the screen.

 

No problem! :thumbup:

Edited November 21, 2010 by BlueRidgeDx