MSA - Minimum safe altitude - Radar Contact Support Forum

September 3, 201312 yr

hey ..

something that bothers me for quite some time i and can't figure this problem out on my own - hope u guys can help me.

Example: Flight from EDDT to LOWW (Berlin Tegel to Vienna)

Controller tells me when I'm on the approach channel: expect vectors to the runway 16 for instance

before getting on the ILS glideslope he tells me fly heading ... descend 3500 feet.

My question: when i open RC and then the Controller Info stated under MSA : 3200 feet.

Can someone pls explain to me how the difference of 300 feet is calculated?

Because its always a difference between the stated MSA in RC Controller Info and what the controller tells me, depending on the airport.

Hope i made it clear what the problem is

thanks in advance

Intel Core i9-12900K | 16x 3.20 GHz, 30MB L3-Cache; Gigabyte Z690 AORUS AORUS Pro | Intel Z690; NVIDIA GeForce RTX 3080 Ti 12GB | Gigabyte Gaming OC; 2 TB Samsung 980 PRO PCIe 4.0; Meta Quest 2, HP Reverb G2 Rev 2

September 3, 201312 yr

I downloaded the ILS approach charts of LOWW from Eurocontrol (free registration). If you want them reply and I'll take you through the query procedure.

RC has a database of average terrain height calculated from published MSAs in the quadrants surrounding the airport as noted on instrument and VFR charts. A certain bias has been added and then using the average three degree glide slope determines a safe altitude for the GS/LOC intercept and vector eights for the pattern.

Give me a few hours (necessary chores right now) and with chart excerpts I'll illustrate what is going on and take you through retrieving some of the charts.

These particular LOWW charts have color mapped terrain (topographic) charts and are among the best to interpret.

I'll also describe the user of NOTAMS in RC to get flexibility in variable terrain and the use of IAP for non-radar guidance that allows you to follow a chart on your own without RC instructions from 40 nm out until you are on final when the average terrain altitude does not work.

September 4, 201312 yr

First here is a VFR chart extract (copyright skyvector.com) showing MSAs around LOWW:

<a data-ipb="nomediaparse" href="http://skyvector.com/?ll=47.968778258212836,16.627532952003314&chart=301&zoom=4">http://skyvector.com/?ll=47.968778258212836,16.627532952003314&chart=301&zoom=4</a>

In each quad (square with longitude and latitude lines) you'll see a number in blue like these I outlined in red:

The 27 stands for an MSA of 2,700 feet in that quad. LOWW is about the center of the map. Note the high terrain to the west.

From an instrument chart for a runway approach there is an MSA insert that looks like this (outlined in red and also the contour legend) extract from Eurocontrol - not for real world use:

and here is the approach vertical profile for ILS 16:

I did a quick auto generated plan in FSBuuild 2.4 with an Airac a few months ago. The route is here:

EDDH AMLU7D AMLUH UL619 BUMIL UM748 HDO UM725 OKF UL858 LANUX.LANU6W LOWW

and if you wish to load it in FS9 the .pln is:

[flightplan]

title=EDDH to LOWW

description=EDDH, LOWW

type=IFR

routetype=3

cruising_altitude=37000

departure_id=EDDH, N53* 37.49', E009* 59.17',+000053.00

departure_position=15

destination_id=LOWW, N48* 06.37', E016* 34.10',+000600.00

departure_name=HAMBURG

destination_name=VIENNA/SCHWECHAT

waypoint.0=EDDH, A, N53* 37.49', E009* 59.17', +000000.00,

waypoint.1=DH204, I, N53* 29.42', E010* 06.39', +000000.00,

waypoint.2=AMLUH, I, N53* 25.44', E010* 19.21', +000000.00, UL619

waypoint.3=BUMIL, I, N53* 07.11', E011* 17.09', +000000.00, UM748

waypoint.4=GURLO, I, N53* 03.06', E011* 22.24', +000000.00, UM748

waypoint.5=ERNUD, I, N52* 56.02', E011* 31.32', +000000.00, UM748

waypoint.6=SOGMA, I, N52* 38.07', E011* 54.19', +000000.00, UM748

waypoint.7=DEXUG, I, N52* 24.01', E012* 15.37', +000000.00, UM748

waypoint.8=SOBLU, I, N52* 23.31', E012* 16.22', +000000.00, UM748

waypoint.9=SUKIP, I, N52* 15.32', E012* 28.17', +000000.00, UM748

waypoint.10=ESIKA, I, N52* 07.26', E012* 40.17', +000000.00, UM748

waypoint.11=MOSEX, I, N51* 55.09', E012* 58.14', +000000.00, UM748

waypoint.12=BOLBO, I, N51* 47.40', E013* 09.03', +000000.00, UM748

waypoint.13=OLBIK, I, N51* 39.45', E013* 20.27', +000000.00, UM748

waypoint.14=OSKAN, I, N51* 27.39', E013* 37.39', +000000.00, UM748

waypoint.15=RENDO, I, N51* 16.41', E013* 53.04', +000000.00, UM748

waypoint.16=ESLOR, I, N51* 03.56', E014* 10.45', +000000.00, UM748

waypoint.17=HDO, V, N50* 55.41', E014* 22.07', +000000.00, UM725

waypoint.18=ODLIV, I, N50* 40.13', E014* 27.52', +000000.00, UM725

waypoint.19=BAVIN, I, N49* 56.42', E014* 43.41', +000000.00, UM725

waypoint.20=VOZ, V, N49* 31.56', E014* 52.28', +000000.00, UM725

waypoint.21=OKF, V, N48* 58.09', E015* 32.44', +000000.00, UL858

waypoint.22=LANUX, I, N48* 53.17', E015* 36.56', +000000.00,

waypoint.23=NERDU, I, N48* 28.53', E016* 05.57', +000000.00,

waypoint.24=LOWW, A, N48* 06.37', E016* 34.10', +000000.00,

and in FSX format:

<?xml version="1.0" encoding="Windows-1252"?>

<SimBase.Document Type="AceXML" version="1,0">

<Descr>AceXML Document</Descr>

<FlightPlan.FlightPlan>

<RouteType>HighAlt</RouteType>

<DepartureName>HAMBURG</DepartureName>

<DestinationName>VIENNA/SCHWECHAT</DestinationName>

</AppVersion>

<ATCWaypointType>Airport</ATCWaypointType>

<ICAO>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>AMLUH</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>BUMIL</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>GURLO</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>ERNUD</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>SOGMA</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>DEXUG</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>SOBLU</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>SUKIP</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>ESIKA</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>MOSEX</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>BOLBO</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>OLBIK</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>OSKAN</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>RENDO</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>ESLOR</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ICAO>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>ODLIV</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>BAVIN</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ICAO>

</ICAO>

</ATCWaypoint>

<ICAO>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>LANUX</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Intersection</ATCWaypointType>

<ICAO>

<ICAOIdent>NERDU</ICAOIdent>

</ICAO>

</ATCWaypoint>

<ATCWaypointType>Airport</ATCWaypointType>

<ICAO>

</ICAO>

</ATCWaypoint>

</FlightPlan.FlightPlan>

</SimBase.Document>

The RC Controller page shows;

an MSA of 3200 feet which is a minimum safe merge altitude for the localizer/glide slope merge 9 nm out. This is the minimum for all quadrants about 15 nm out.

Something like that.

Now if you wish access to current charts from Eurocontrol register on the login page:

http://ead-website.ead-it.com/publicuser/public/pu/login.jsp

You will get an e-mail from them to verify your account. Then return after verifying to the login page and login.

Click Enter Applications. We will use LOWW for our example. Click on the agreement OK, then click on PAMS Lite. A query screen will open in a few seconds. Select the following:

authority: Austria (LO)

Type: Civil

Language: EN

AIP Type: Charts

Part: AD -- for airport directory

Click to check Advanced

Click Search to get the Advanced Pop-up Window

In Document Name enter *LOWW* to get all LOWW charts in a main window.

There may be more than one page and if so use the arrows in the Page navigation line to progress or go back to the different listings. This example shows only one page of listings.

Column 4 has the document title such as:

Column 2 has the links to charts in .pdf format. In this example click on:

and the chart will load in Acrobat Reader (the only one to use since for copy protection this file is encrypted with read only protection for Acrobat). In Acrobat you can choose File/Save Page As and re-title to suit the .pdf such as LOWW Cat II-III RWY 16 ILS in the folder of your choice. You can also print this document. You can not copy-paste, select a section, get snapshot, etc., due to its protection.

In this case you might want the airport diagram, parking, etc., SIDS, STARS, and other applicable navigation charts.

In preparing your flight plan it is best to let RC determine assigned runways since ai behavior has first priority, then weather and runway facilities. Where SIDs and STARs are runway specific, use your flight plan sent to RC containing only common points to all runways. After RC assigns your runways if your aircraft is equipped select the procedure for the runways assigned. If an FMC is useed with a procedure database, be sure using an AIRAC update for it and your flight planner so RC and your navigation equipment has the same data for waypoints. In RC all waypoints from 30 nm from departing airport to 40 nm from arrival airport are considered enroute and must be in the plan sent to RC. If you first waypoint is within 30 nm of your departing airport you have no vectors but you can choose RC altitude assignments or not. In this case you will have to follow your own navigation to line up with the first waypoint outside of 30 nm. You will only have two out of three choices on the RC screen. If your first waypoint is outside that boundary and you'll have three choice with No Dep Procedure available (by default) to get departing vectors to line you up with that first waypoint outside of 30 nm.

On arrival you have the choice of letting RC vector you the last 35 nm or you can select an IAP to do your own navigation by FMC or other means. When you get your approach runway assignment acknowledge it and if you wish not to get vectors request an IAP choosing the same runway as suggested by RC. RC will then allow you to use your FMC navigation keeping quiet until you are on final. It will suggest an altitude to merge onto the localizer/ILS glide slope.

I realize this is a lot but since I got into charts to answer your question, i thought I'd take you through the take-off departure and arrival-approach to sync RC and your aircraft guidance and planner. Tutorials in the RC 4.3 manual show some of this.

For some other flexibility check out the NOTAMS feature in the manual. The controllers will niot be quite so rigid except for the crossing altitude. Be sure you understand transition altitudes and levels and setting your barometric pressure as outlined in the manual.

You might wish to save this reply somewhere as a document for reference.

It takes longer to read this then to implement these procedures once you get the hang of it.

Good luck in your pursuits.

September 4, 201312 yr

It looks like I broke AVSIM's format. Please try to disregard the text codes.

September 5, 201312 yr

Author

Thank u for the info.. appreciate it.. now its clear to me how rc calculates the msa.. thank u..

Kind regards

Intel Core i9-12900K | 16x 3.20 GHz, 30MB L3-Cache; Gigabyte Z690 AORUS AORUS Pro | Intel Z690; NVIDIA GeForce RTX 3080 Ti 12GB | Gigabyte Gaming OC; 2 TB Samsung 980 PRO PCIe 4.0; Meta Quest 2, HP Reverb G2 Rev 2

September 5, 201312 yr

Commercial Member

long ago, i wrote a program that analyzed the topographic data of the earth, and calculated the highest point in every 1 degree square, and then wrote that out into an xls file. the discrepancy you noted is based on a real world chart compared to a calculation.

JD

Read my blog

September 5, 201312 yr

Hi, jd:

Do you recall the radius that you used from the airport center (if you used this technique) to get the raw terrain altitude and then average it?

Thanks.

MSA - Minimum safe altitude

Featured Replies

Create an account or sign in to comment

Account

Navigation

Search

Configure browser push notifications

Chrome (Android)

Chrome (Desktop)

Safari (iOS 16.4+)

Safari (macOS)

Edge (Android)

Edge (Desktop)

Firefox (Android)

Firefox (Desktop)