Dear All:How do you determine the Missed Approach Point on an RNAV plate? I can't seem to find any indication of one on RWY 31R in Chicago's KMDW airport. On this RNAV plate I see that the MDA is 1060, but what is the MAP or Decision Height/Decision Altitude? Do these GPS plates ever have a Missed Approach Point or DH listed?Thanks.Chris Catalano

If you look at the vertical profile on the plate you'll see at 1060 a constant altitude (the MDA) going to the threshold of 31R. That is as far as you can go as noted by the dashed climb line, the threshold, at which point you do missed. Depending on the aircraft requirements worst case for runway length, since the AGL of the MDA is 400, you must decide if you can accommodate the reduced runway available in getting down from the 400 AGL if you can see the runway before the threshold. It looks like the runway is about 6100 feet so if you are operating an aircraft that can stop at 3500 feet such as some regional jets and turboprops and operate safely at the slowest speed, you might chance it. 3500 feet approx is the length of the MDA to the threshold so if you can see the runway halfway through at 1800 feet and you can safely with margin land with 4300 feet you can rescue the landing but you've got to be configured for it.In this situation you are declaring your own MAP based on your aircraft and policies within that 1800 feet MDA portion.If you are in low visibility I'd request 31C for its longer length and better lighting aids at the threshold when flying a heavy or none-STOL aircraft. Remember that all you have to see is the threshold lights.One more aid is to see if an RVR is reported for the specific runway as well.

Ron,Are you sure about the MAP being "In this situation you are declaring your own MAP based on your aircraft and policies within that 1800 feet MDA portion"I would think..the MAP is the threshold. Period. What you said earlier "That is as far as you can go as noted by the dashed climb line, the threshold, at which point you do missed. "If you decide to go missed sooner ("The earlier point" does NOT become a MAP), you may start climbing earlier..but you cannot turn (If there is a turn instruction in Missed approach procedure) until after your MAP. In this case (RNAV 31R KMDW) your MAP is the threshold. You could have a bulding before the runway threshold... and if your Missed approach procedure says..make a climbing turn to the right.. you could hit the building if you execute your procedure before reaching the MAP. in this case..the rwy threshold.The earlier point to start descending,... is the VDP (Visual Descent Point). This is somtimes given with a small v in the profile view. But many don't provide like in this particular chart. But you can calculate it to give you a 3 degree normal descend.BTW Chris. DA (Decision altitude is for precision approaches (ILS). GPS/RNAV approaches are non precision approaches using MDAs)

Besides the VDP, you can descend a little ways down when you have the approach lights in view (the altitude escapse me right now and I need to get running so I don't have time to look it up). I think it's 100 feet below MDA, but I'm not sure off hand and I'm sure one of these guys can give it to you. And any time you have a clear view of the runway environment, you may descend before reaching the MAP. Just make sure it's a clear view, if you lose sight of it (i.e. a low cloud comes between you on the way down), you must go missed at that point. Generally on a GPS approach, there's a MAP fix that's the runway name such as "RW03" and on the NACO charts is a tiny GPS waypoint symbol in a circle. It's called, conviniently, a MAP Waypoint. I know in the Bendix/King Gps we use in our aircraft have the waypoints designated with a suffix of "i" for IAF, "f" for FAF, and "m" for MAP. So in my example, it would be shown as "RW03m".----------------------------------------------------------------John MorganReal World: KGEG, UND Aerospace Spokane Satillite, Private ASEL 141.2 hrs, 314 landings, 46 inst. apprs.Virtual: MSFS 2004"There is a feeling about an airport that no other piece of ground can have. No matter what the name of the country on whose land it lies, an airport is a place you can see and touch that leads to a reality that can only be thought and felt." - The Bridge Across Forever: A Love Story by Richard Bach

Hi John,With the ALS *only* in sight, one may descend to 100' ATZE (AGL above touch-down zone), but no lower. Check the chart for this.I don't have the plate being discussed so can't comment on the MAP- but often a GPS approach is the threshold itself. Of course, one must be "continuously in a position to land "normally" " or a missed is also required (for any approach).Bruce.

You are right. I meant you can start your climb if you need to but you still have to follow the horizontal path indicated. Bad choice of words on my part. What I meant was if the aircraft can handle the shorter runway and roll-out you can start the descent anywhere along that MDA 1800 foot path if you have a delayed view of the threshold lights in site and land a little further down as long as you can stop.Thanks for the correction.

hi allon a side topicive seen on approach plates, different Category like A B C and Dwhat is a 737/800 AC, what category?

I don't believe I've seen a GPS IAP where there wasn't a waypoint identified as the MAP. If you don't have the runway in sight ever, then how would you know you're corssing the threshold?Some are at the runway threshold, but for the GPS RWY 3L into KSFF, the MAP is at "GENEY" (Or as it shows in the atleast Bendix/King KLN-89N when you set the approach, "GENEYm") .5nm away from the runway. The symbols in the picture below come in two sizes, one that is half the size of all the other waypoint symbols that looks like that is a MAP WayPoint. If it's that symbol, but normal size it is a Crossover Waypoint.KMDW RNAV (GPS) RWY 31R and the MAP circled in magentahttp://forums.avsim.net/user_files/135958.jpgKSFF RNAV (GPS) RWY 3L and the MAP circled in magenta http://forums.avsim.net/user_files/135959.jpg----------------------------------------------------------------John MorganReal World: KGEG, UND Aerospace Spokane Satillite, Private ASEL 141.2 hrs, 314 landings, 46 inst. apprs.Virtual: MSFS 2004"There is a feeling about an airport that no other piece of ground can have. No matter what the name of the country on whose land it lies, an airport is a place you can see and touch that leads to a reality that can only be thought and felt." - The Bridge Across Forever: A Love Story by Richard Bach

It's 1.3 times the aircraft's V_S0 (Stalls speed in the landing configuration) at the aircrafts maximum weight, or the speed you plan to shoot the approach.To quote what the infomration says in the NACO Terminal Proceedures Publication under "Terms/Landing Minima Data" it puts it this way:Aircraft approach category indicates a grouping of aircraft based on a speed of VREF, if specified, or if VREF not specified, 1.3 VSO at the maximum certificated landing weight. VREF, VSO, and the maximum certified landing weight are those values as established for the aircraft by the certification authority of the country of registry. Helicopters are Category A aircraft. An aircraft shall fit in only one category. However, if it is necessary to operate at a speed in excess of the upper limit of the speed range for an aircraft's category, the minimums for the category for that speed shall be used. For example, an airplane which fits into Category B, but is circling to land at a speed of 145 knots, shall use the approach catagory D minimums. As an additional example, a Category A airplane (or helicopter) which is operating at 130 knots on a straight-in approach shall use the approach Category C minimums.Our Piper Warriors at my flight school are Category A aircraft, but since our flight school calls that we shoot approaches at 100 knots (beacause of considerations for the moderate level jetliner traffic that has to deal with us), we have to use the Category B minimums.Category : SpeedA : 0-90B : 91-120C : 121-140D : 141-165E : Above 165Then there's COPTER which is rarely seen. If not shown on the chart, then Category A is to be used instead of COPTER, since as above it says helicopters are Category A aircraft.For those that haven't seen Category COPTER minima before. Here's a COPTER chart for KAST in Oregon.http://www.myairplane.com/databases/approa...COPTERLD257.PDF----------------------------------------------------------------John MorganReal World: KGEG, UND Aerospace Spokane Satillite, Private ASEL 141.2 hrs, 314 landings, 46 inst. apprs.Virtual: MSFS 2004"There is a feeling about an airport that no other piece of ground can have. No matter what the name of the country on whose land it lies, an airport is a place you can see and touch that leads to a reality that can only be thought and felt." - The Bridge Across Forever: A Love Story by Richard Bach

thanks John for this informationso its safe to assume that 737/800s are CAT D's?

Hi John,Look at my airport KBJC (Jeffco, Colorado). GPS 29R has a MAP of 29R (the runway threshold). The only waypoint is ALIKE, the FAF. The same at neighboring KFNL (Loveland-Fort Collins), where the MAP is 33. However some GPS approaches do have a waypoint as the MAP- and I may have sounded like all GPS approaches were the same, which they are not.However, if you were at the MDA and at the threshold, you most likely would need to make a missed even if you had the r/w environemnt in sight, as another required factor is to be continously in a position to land "normally" (my words)."If you don't have the runway in sight ever, then how would you know you're corssing the threshold?"The magic of GPS.:) Assumes that your GPS is working and you have either a NAV or MAP page up- and that all the other requirements of a GPS approach are in place too. This is the one approach type out of many others such as LOC, NDB, VOR (non-precision) that can actually reference any fix, and is not reliant on a timer, DME, a cross-radial, etc. Bruce.

>I don't believe I've seen a GPS IAP where there wasn't a>waypoint identified as the MAP. If you don't have the runway>in sight ever, then how would you know you're corssing the>threshold?>>Some are at the runway threshold, but for the GPS RWY 3L into>KSFF, the MAP is at "GENEY" (------------------------>John Morgan>Real World: KGEG, UND Aerospace Spokane Satillite, Private>ASEL 141.2 hrs, 314 landings, 46 inst. apprs.>Good point John. In this case the circled star is at the threshold denoting the MAP.

Most of the time it appears that way. The FMC approach page which gives you the Vref in advance runs in the D area.The 700 is borderline if you are travelling with minimum fuel plus reserves. My last flight I came in at 136/40 so you can squeeze or burn off if marginal borderline and you need to make a more restrictive minimum.

Most of my V_REFs have been in the Category C range with the 700, but heavily laden, they stray into the Category D minima requirement.----------------------------------------------------------------John MorganReal World: KGEG, UND Aerospace Spokane Satillite, Private ASEL 141.2 hrs, 314 landings, 46 inst. apprs.Virtual: MSFS 2004"There is a feeling about an airport that no other piece of ground can have. No matter what the name of the country on whose land it lies, an airport is a place you can see and touch that leads to a reality that can only be thought and felt." - The Bridge Across Forever: A Love Story by Richard Bach

If you look at the chart for the GPS approach you mentioned, there are actually two waypoints. ALIKE (with the waypoint symbol) and RW29R (with the MAP waypoint symbol). That would appear in your GPS. I still have yet to see a chart without a MAP waypoint, or an GPS that hasn't had that waypoint showing when I've shot the approach. They put that waypoint in so you can find the MAP. Most are as you say, are indeed over the threshold, but the point is identified clearly on the chart and in the GPS unit so that you can know when you cross it in visibility too poor to see it.----------------------------------------------------------------John MorganReal World: KGEG, UND Aerospace Spokane Satillite, Private ASEL 141.2 hrs, 314 landings, 46 inst. apprs.Virtual: MSFS 2004"There is a feeling about an airport that no other piece of ground can have. No matter what the name of the country on whose land it lies, an airport is a place you can see and touch that leads to a reality that can only be thought and felt." - The Bridge Across Forever: A Love Story by Richard Bach