UNDERSTANDING IFR,WHAT IT IS, HOW TO DO IT
©Hal Stoen, Stoenworks, Inc. September4, 2000
Purpose of this tutorial
To give the flight simmer an idea of what IFR procedures are.What IFR is, how it differs from VFR, how to fly IFR enroute,what IFR approaches are, definitions, and how to "shoot"the various instrument landing procedures. This is not an "IFRTutorial". For the correct procedures to use in the IFR environment,see Andrew Ayer's tutorials on IFR procedures.
The discussion herein are based on those used in the UnitedStates. Other countries vary on details, but the central themeis similar.
About the author
I soloed in 1966 and received my Commercial license severalmonths later. For the next 20-some years I made my living flyingairplanes: flight instructing, charters, mail, commuter airline,and ending up as a corporate pilot for the last 15 years or so.In that time I accumulated over 6,000 hours while operating avariety of aircraft ranging from the single engine Cessna 150to the four engine DeHavilland Heron. During my time, I receivedmy Commercial, Multi-Engine, Flight Instructor Instrument licencesand ratings. I retired from aviation in 1988, and now ride inthe back like most everyone else- and yes, I am a poor passenger.
What is this thing called "IFR"?
"IFR" stands for Instrument Flight Rules, as opposedto "VFR" which stands for Visual Flight Rules. Theseare the two basic divisions of flying IFR, or VFR. For all intentsand purposes, to fly VFR the weather must be a "ceiling"of at least 1,000 feet above the ground, and the visibility mustbe at least 3 statute miles. Just to muddy up the waters, thereis another category named "special VFR", but we'll staywith the two basic divisions.
For VFR flight, it's see and be seen, hop in your aircraftand go. As long as you stay away from "controlled airspace"you can go and do what you want to- as long as you don't violateany regulations of course.
For IFR flight, you must have the permission of ATC, Air TrafficControl, to operate in controlled airspace.
Glossary (an attempt at "non-tech"definitions)
ARTCC: Air Route Traffic Control Center. Oftencalled "Center". The United States is divided into divisions,roughly based on the amount of traffic that they control. Thus,New York Center's geographic airspace is smaller than Minneapolis'airspace. Within the various Centers are more divisions that areusually worked by a single controller.
ATIS: Automatic Terminal Information Service.A continuous broadcast of the airport conditions. As conditionschange, the change is noted by an alphabetical increase in thename of the broadcast. Information "Charley" becomesinformation "Delta", etc.
ADF: Automatic Direction Finder. A low frequencydevice that can point at a radio station. The term "ADF"can sometimes refer to the tuner head that tunes the ADFfrequencies, or the display head. (see the illustrations thatfollow)
Ceiling: The height from the surface to the lowestlayer of clouds that are reported as "broken", "overcast",or "obscuration", but not classified as "thin"or "partial".
Center: A common abbreviation for ARTCC.
Clearance: 1. Your IFR clearance for your intendedroute, or approach.
2. An abbreviation for Clearance Delivery, a feature that is available at larger airports. Clearance Delivery has a devoted radio frequency that you can use to get your IFR clearance. Once you have obtained it, you then contact Ground Control for taxi instructions.
Controlled airspace: Just about all of the airspacein the United States. There are several categories.
Continental Control Area: Covers all of the "lower 48" plus most of Alaska. Extends from 1,501 feet above the surface up to infinity, or the base of the PCA, the Positive Control Area.
Control Zone: The area around an airport that has a control tower. Usually a 5 statute mile circle around the airport, and any extensions necessary for instrument approaches. It extends from the surface to the base of the Continental Control Area.
Positive Control Area: The airspace extending from 18,000 feet MSL to Flight Level 600 (for all intents and purposes 60,000 feet).
TCA: Terminal Control Area. Airspace around larger airports. VFR or IFR, you need permission to be in there.
Controller: A person that works at a controltower or at ARTCC.
CDI: Course Deviation Indicator on the HSI.
CTAF: Common Traffic Advisory Frequency. A radiofrequency that is used to broadcast on when the controlling facilityfor an airport, the tower for example, is not in operation.
DA: Decision Altitude. Minimum descent altitudeon a precision approach, in feet above sea level (msl).
DH: Decision Height. Minimum descent altitudeon a precision approach, in feet above the ground (agl).
DME: Distance Measuring Equipment. The readouton your DME will give the distance from the station that yournav. radio is tuned to.
FAF: Final Approach Fix. The point from whichthe final approach (IFR) to an airport is executed. It is shownon some approach plates as a Maltese Cross for non-precision approaches,and by the glide slope/path intercept point on precision approaches.
IFR: Meteorological conditions that are lessthan VFR. IE: ceilings less than 1,000 feet and visibility lessthan 3 statute miles.
ILS: Instrument Landing Sysrem. An approach thatprovides both vertical (glide slope), and horizontal (localizer)information.
LOM: Locator, Outer Marker. A NDB that is co-locatedwith the Outer Marker associated with an ILS. This allows usingthe ADF for orientation on the approach.
MAP: Missed Approach Point. That point at theend of an approach where, if you cannot see the runway to land,you terminate the approach, and go into the Missed Approach mode.
MDA: Minimum Descent Altitude. The lowest altitude(msl) that you can descend to on a non-precision approach.
Missed Approach: The segment flown between theMAP (see above) and the Missed Approach fix.
MSL: Mean Sea Level. The average height of theworld's oceans.
NDB: Non-Directional Beacon. A low frequencyradio beacon that radiates it's signal in all directions.
OM: Outer Marker. A beacon that radiates a signalthat is received in an aircraft shooting the approach. The OuterMarker is usually about 5 miles from the end of the runway.
Non-Precision approach: An approach without aglide slope.
Precision approach: An approach with a glideslope.
Special VFR: When authorized by ATC, VFR flightwith at least 1 mile visibility, and remaining clear of clouds.
TACAN: Military format for azimuth and distance.
VFR: Ceilings more than 1,000 feet and visibilitythree miles or greater.
VOR: Very-high Omnidirectional Range. A VHF stationthat gives azimuth information for aircraft navigation. See
VOR/DME: A VOR that has DME capabilities also.
VORTAC: A VOR that has DME available in additionto TACAN. Don't worry about the TACAN part. Unless you have militaryreceivers you won't get the signal. From a civilian standpoint,regard VORTAC's the same as a VOR/DME station.
What training do I need, as a sim.pilot, to fly IFR?
You should be able to fly your airplane of choice solely bythe instruments on the panel, without looking out the windows.In addition, you should be familiar with navigation procedures.(If you have not read UnderstandingVOR's, and How to navigate,I would suggest that you do so when time permits.)
In addition, you should have a good working understanding ofhow the various instruments on the aircraft's panel operate andhow to set them up for navigation.
What equipment do I need in myairplane to fly IFR?
(all of the instruments shown below are discussed in detailin the "How to flycomputer flight simulators" tutorial)
The short of it: magnetic compass, Needle and Ball, airspeedindicator and an altimeter. "Needle and Ball" referto the Turn and Bank indicator.
With these basic instruments you can fly IFR. It wouldn't bepretty, but you could do it.
Let's make up a more functional group and discuss them justa little. You don't need everyone of the following items, butin this tutorial I will refer to various procedures as if youraircraft has at least the following items.
Thecompass. Sometimes referred to as a "wet" or "dry"compass. These are as basic as it gets, they point at magneticNorth. A "wet" compass floats in a kerosene-like fluid,while a "dry" compass is just that. They require nooutside information. The compass is a difficult instrument touse for heading information due to a whole bunch of turning momentsthat are induced into it by the aircraft's acceleration and turning.But, it is a 100% back-up, just in case a more complex headinginstrument fails.
The Turn and Bank Indicator. Sometimes referred to as the "needleand ball" for a more traditional instrument that replacesthe "little airplane" with a needle, and the "verticalline" with a ball.
Theairspeed indicator. Hey, you have to know how fast, or slow, yourairplane is going.
Thealtimeter.
TheArtificial Horizon, or also known as the Attitude Indicator.
TheHSI, Horizontal Situation Indicator, usually "driven"by the number one navigation receiver.
Comm./Nav.One, and Comm./Nav Two. You need these babies to transmit andreceive voice communications, and to receive navigational information.While you could venture forth with only one communications radio,and one navigation receiver, it would be a risky venture at best.
VORhead, usually "driven" by the number two navigationreceiver.
TheADF, Automatic Direction Finder display, "driven" bythe ADF tuner head 
TheADF tuner head.
DME,Distance Measuring Equipment. "Driven" (tuned) by eitherthe number one navigation receiver, "N1" on the panel,or the number two navigation receiver, "N2" on the panel.
Transponder.This fellow, when set to a discreet code will let Center knowwho you are.
So, how do you "become"an IFR flight?
Two ways, basically. You can file an IFR flight plan, then"pick it up" from Clearance or Ground Control beforeyou depart, or you can file in the air by contacting Center andtelling them what you want to do.
Ah, then how do I get "out"of an IFR flight?
Several ways. If you land at an airport with a Control Tower,your IFR is automatically cancelled upon landing. If you landat an airport without a Control Tower you will have to requestthat your IFR is cancelled either by using your radio, or makinga telephone call once on the ground. And, of course, if the weatheris VFR and you're not in controlled airspace, you can cancel IFRjust by telling Center. "Center, Red Baron 123 is cancellingIFR at this time."
OK, how do I figure out how toget from "here" to "there"?
This example will be for going from where you are, to an airportthat is within the area shown on the X-Plane built in chart. Goup into the menu and find the charts. You will be able to zoomin on the airport you are located at. Note the name and frequencyof the nearest VOR that is along your intended path to your destinationairport. Zoom in or out as necessary to locate the airport thatyou intend to land at, and the nearest VOR.. File your flightplan from the airport you are at to the VOR nearest that airport,then to the VOR nearest your destination airport, then to theairport that you want to land at.
In its simplest form, that will get you from "here"to "there". Well great, what if you want to go fromLos Angeles to New York? In that case you will have to locatesome charts that show the routes available between those two points.Sim charts are available on the net at several locations, or youcan purchase charts through the mail or at your local airport.If you have not done so, now would be a good time to read Understanding VOR's and
Alright, I understand VOR's andhow to navigate. How do you fly all of those various instrumentapproaches?
In this segment we'll cover that. The subjects covered willbe: Transitioning from enroute to the approach phase, SID's andSTAR's,VOR approaches, VOR/DME approaches, NDB approaches, Localalizerapproaches, the ILS, and lastly the Back Course approach.
Transitioning from enroute to theapproach phase
As you near your destination airport, Center will call andeither give you a lower altitude or instructions to contact ApproachControl, or a combination of both of these instructions. Somethinglike "Red Baron 123, descend to and maintain 7,000.",or "Red Baron 123, descend to and maintain 7,000. ContactApproach on 124.7."
SID's and STAR's
These are printed guides that show in graphic and text formthe standard departure and arrival routes for a given airport.Not all airports have them, usually only the busiest ones do.
A SID is a Standard Instrument Departure. If you are issueda Sid as a part of your departure clearance, you are expectedto follow the instructions on the chart. The example below isfor Tucson International Airport, KTUS.
Thechart is self explanatory. One note that is very important though.Once Departure gives you a different heading or altitude thanthose that are shown on the SID, the procedure is over. The SIDis only valid if you are following all of the directions on thechart. If anything changes, altitude, heading etc., then the SIDis no longer in effect. SID's are an effective way to send aircraftout on their various routes in a planned and organized fashion.
A STAR is a Standard Terminal Arrival Route. If you are issueda STAR as a part of your arrival clearance, you are expected tofollow the instructions on the chart. The example below is forTucson International Airport, KTUS.
Thechart is self explanatory. One note that is very important though.Once Approach gives you a different heading or altitude than thosethat are shown on the STAR, the procedure is over. The STAR isonly valid if you are following all of the directions on the chart.If anything changes, altitude, heading etc., then the STAR isno longer in effect. STAR's are an effective way to bring aircraftin from their various routes in a planned and organized fashion.
This ends the "Introduction to IFR" tutorial. Seethe Tutorial Section for further guides on various approaches.
This tutorial is available on aCD
This tutorial, along with additional content, is availableon a CD. Click here formore information.
© Hal Stoen, September 4, 2000
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