Instrument Approach Plates

What an incredible advance the NDB and ADF brought to instrument flying. Their capability went vastly beyond that of the four-course radio range. For the first time, an aircraft could now approach an airfield that it could not see, to a runway that it could not see until very near, and safely land. What a boost that gave to airline on-time performance.

Using the ADF with the NDB, flights can routinely land in prevailing weather of 600 ft ceiling, or less, and only one-mile visibility. Compare that with the nominal 1000 ft ceiling and three-mile visibility requirement of a VFR flight.

The FAA publishes approved instrument approaches for U.S. airports. Aircraft performing instrument approaches must conform to these published procedures. Instrument Approach Plates, as these charts were once officially called but now Instrument Approach Procedures, are published for and named after the Navaid used for the approach. This could be an NDB, VOR, ILS, LOC, RNAV, or GPS. Some approaches also require DME or availability of airport radar.

Only NDB approaches will be discussed here. Master them and all of the other approaches follow easily.

Note that the entire discussion pertains to approaches to airports in instrument conditions. Nowhere is the word "landing" used. That is the pilot's decision within the limits of each published approach procedure.

Yes, despite the emphasis that follows on IFR approaches, aircraft do take off in IFR conditions, too. In the absence of countermanding limits at specific airports, a one or two engine aircraft must have at least one-mile visibility to take off. Aircraft with more than two engines require only a half-mile visibility. In neither case are ceilings specified. Individual airports may have minimum ceiling requirements, with 300 ft. being very common.

A pilot is advised to carefully consider whether to takeoff at these minimums. If the minimum conditions for takeoff are 300 ft. and one-mile, but the only IFR approach procedure requires 500 ft and one-mile, a return to the airport for whatever reason would not be possible.

The Approach Plate

The arrangement and location of content of all approach plates is identical. To assist in learning the approach plates and NDB approaches, I recommend that you buy one volume of the FAA publication U.S. Terminal Procedures. The FAA divided the U.S. into twenty-four regions, as shown, and the publication price for any one region is only $3.00. In the meantime, click on the Millville NDB approach plate at the top of this section for a full-detailed print.

You can download US Instrument Approach Plates for free on line.

Here is the coverage chart for Terminal Publication Volumes:

Twenty-four volumes of Terminal Procedures cover the contiguous 48 states.

One brief note on the ILS, the granddaddy of all of the instrument landing systems, before moving on. The ILS, or Instrument Landing System, is a precision approach system. It provides glide-path information in addition to a localizer signal to guide the aircraft to the runway. None of the other approach procedures provide glide-path information and hence are called non-precision approaches. ILS landing minimums are lower than all of the other approach procedures.

Approach Plate Features

The most efficient way to explain the features of an approach plate is to work from the top-left to the bottom-right. Following the explanations will be easier, though, if you first print Millville's NDB Runway 14 approach plate.

To add a small amount of confusion, the FAA is changing the format of it's approach plates. The most significant change is in the header information. We will discuss the new format below, but when you encounter the old format, even though slightly diffferent, you will understand its features just as well.

The Left Header

• NDB RNB 363 is the Navaid information for this approach ... NDB identifies this as an Approach Procedure using an NDB, RNB is the three-letter identifier of the NDB, and 363 is the NDB frequency, here 363 kHz.

• APP CRS 147° is the Magnetic Course to the runway for this Instrument Approach.

• Rwy ldg 5057 is the available length of runway for landing, here 5057 feet.

• TDZE 82 is the Touch Down Zone Elevation of the runway, above Mean Sea Level, MSL. Here it is 82 feet. The TDZ is that portion of the runway where an aircraft's landing gear normally first contacts the runway when landing.

• Apt Elev 86 is the Airport Elevation at some central point. Here it is 86 feet, or four feet higher than the TDZE of Rwy 14.

The Right Header

This Instrument Approach Plate (IAP) describes the procedure for either an NDB or GPS approach to Runway 14.

Below that is the airport name, Millville Municipal, followed by its three or four letter airport designator, MIV. The airport name is important for cities with several airports. Be certain you've got the right approach plate in front of you.

In some cases, a runway is not listed in the header, for example, VOR–A. That means that the published approach path is not aligned within 30° of any runway heading. In that case, once the airport is in sight the aircraft must turn to line up with the desired runway.

Second Row – Left Side

The white "T" in the black triangle indicates either that the takeoff minimums are non-standard or that there is a published departure procedure, or both. You will find this information in the front of the approach chart booklet.

At Millville, the take-off minimum is 300 ft ceiling and one-mile visibility for all categories of aircraft. A published departure procedure also exists, named LEEAH TWO. The text description of this departure, when take-off is from Runway 10 or 14:

Climb to 400 ft. Turn left heading 100° and intercept SIE R–333 (SIE VOR, 333° radial) to LEEAH INT, then via ... Maintain 2500 ft., expect filed altitude 10 minutes after departure.

The standard takeoff minimums are for aircraft with two engines or less is one statute mile. For aircraft with more than two engines the take-off minimum is one-half statute mile. In both cases, no ceiling is specified.

Second Row – Center Section

The center section of the second row defines the Approach Lighting System for the specific runway listed on the approach plate that you are using. Runway 14 at Millville, while lighted for night operations, has no approach lighting system on that runway. So let's take a look at the header information, second row, for the ILS RWY 17 approach at Manchester, New Hampshire, KMHT.

MALSR designates a Medium intensity Approach Lighting System with Runway alignment indicator lights. The dot on the A5 symbol denotes the presence of sequenced flashing lights ... a "Rabbit." Explanations of the various approach lighting systems, and there are many, appear in the Instrument Approach Plate booklet.

Second Row – Right Side

Looking again at the NDB RWY 14 approach at Millville, New Jersey, the right side of the second row of header information provides the Missed Approach Procedure.

Third Row – Communication Frequencies

Uncontrolled Field ... No Control Tower

The communications information is listed across the page in the order that a pilot would use it. The first frequency is approach control. It lists Atlantic City App Con so we know that the radar is not at Millville. That's the first clue that Millville Municipal Airport is not a controlled field. Approach Control's frequency is 124.6 MHz or 327.125 MHz for military aircraft.

Millville Radio is next to the right, and is the Flight Service Station, which is on the field at Millville. It is not a control tower, but rather a source of flight information. Pilots can get the latest weather information from them, file flight plans, learn of advisories, etc. Millville's frequency is 123.65. CTAF following the frequency signifies the Common Traffic Advisory Frequency for Millville. Pilots announce their intentions over this frequency, much as with Unicom, but know that the specific coverage is for the Millville Airport only. CTAF is only available at fields without a control tower, to increase safety while in or near the traffic pattern.

UNICOM, a channel also for pilots to announce their intentions at an uncontrolled field, is on 123.0 MHz. The "L" in the dark circle following the Unicom frequency indicates the availability of Pilot Controlled Lighting. By rapidly keying his Microphone on Unicom the pilot can turn on the runway lights. The pilot can control up to three different intensity levels of lighting depending on the particular microphone keying used.

ASOS is Automated Surface Observation System, which continuously measures and broadcasts, minute by minute, the surface weather conditions at an airport. The Millville information is available on 128.125 MHz. When installations are complete, this system will be on 1700 airports. The Airport/Facilities Directory includes ASOS information, including broadcast frequencies and telephone numbers for phone-line connections to the broadcasts. Check http://adds.aviationweather.noaa.gov for ASOS and weather information for an airport near you.

Controlled Field

Plan View Panel

We're back to the NDB RWY 14 approach at Millville, New Jersey. The largest section of an approach plate is the plan view, or "top view" of the approach.

Old Format Plan View

The ASOS listed without a frequency means that the service is available, however, the information can only be obtained over the telephone. With ATIS on the field and Approach Control reporting current conditions if they differ from ATIS, it's not necessary to also broadcast the ASOS information.

Minimum Safe Altitude—MSA

If the Navaid were a VOR, the center symbol would be the familiar VOR symbol found on sectional charts. The center symbol corresponds to the Navaid used for the approach, or will be a waypoint symbol if flying a GPS approach.

If you are within 25 NM of Millville, you must fly at or above 2100 ft to clear all obstructions by at least 1000 ft. This MSA is independent of your magnetic heading towards RBN NDB.

More than one MSA can be designated for any given approach Navaid, as the Manchester diagram shows. Here are the three MSAs for DRY NDB:

• 3400 ft if approaching from the North, magnetic course between 046° and 226°.
• 2600 ft if approaching from the East, magnetic course between 226° and 316°.
• 2000 ft if approaching from the South, magnetic course between 316° and 046°.

Note that the direction of fligh for multiple MSAs is defined by your Magnetic Course not your heading.

Approach—Plan View

Click the image to print this plate imprinted with the identifying letters.

The plan-view features are explained below in the order that a pilot confronts them. Letters "A" through "K" defines this sequence. Click on the image above to print the approach plate imprinted with these identifying letters to follow the explanation.

1. Identify the NDB—be certain that you are approaching the correct beacon. Frequency indication on the receiver is not sufficient because LF beacons can have great range. Listen for the ident Morse code as shown in the Navigation box. The IAF at the top of the box means that this Navaid is the Initial Approach Fix for this instrument approach. All approaches start somewhere, and that place is the IAF.
2. The Navaid here is Rainbow NDB, ident RNB. Approach the airfield by tracking to the NDB.
3. On reaching the IAF, turn OUTBOUND from the airport. In this case, the track (compensating for wind) should be 327°.
4. Track outbound from the IAF for two minutes, then start the procedure turn. Here it is a left turn to 282°. Note that the line with a half-arrow head indicates that a procedure turn is a mandatory part of the approach procedure.
5. Proceed on the 282° heading for a minute or so, then turn AWAY from the airport to the reciprocal heading of 102° to return back to the approach course to the field.
6. As the ADF indicator nears the 147° bearing to the NDB, turn inbound, right in this case, and track to the NDB on that bearing.
7. Continue inbound until the field and runway 14 is in sight. The miniature airport plan "G" accurately portrays the runway layout in relation to your inbound track.
8. If the runway is not in sight when it should be, a missed approach is mandatory. "H" shows that a right turn is required to perform a missed approach.
9. The missed approach procedure generally sends the aircraft to the Navaid and into a holding pattern to await further instructions from ATC. "I" shows the holding pattern and the proper headings. It also shows, in this case, that the holding pattern requires right turns.
10. Before beginning the approach, take note of the obstructions. By now you are aware that antenna towers seem to cluster near airports. Know generally where they are and their height.
11. The circle surrounding the plan view of the approach procedure is 10 nm in radius, centered on the Navaid. You are expected to remain within this 10 nm. distance from the beacon while performing the approach. i.e., don't fly a 20 nm outbound leg, or 15 nm after turning into the procedure turn. You only own the airspace within the 10 nm radius circle.

OK, I give up—what's a procedure turn?

It's common to execute the procedure turn about two minutes out from the beacon. That time is flexible, but too little rushes you too much on the return to the beacon and too long may take you outside the mandatory 10 nm. radius that you must remain within.

There's an unpublicized hazard, too, with a procedure turn that begins a loooong way out from the beacon. That's the bevy of pilots of high-performance aircraft asking to see you, the ones that you delayed while you moseyed that long distance back to the beacon at a nice leisurely pace.

The procedure turn begins with a 45° turn away from the outbound track. Fly that heading for a minute or so, nothing hard and fast about that time, then execute a 180° turn away from the airport to return to the desired bearing to the beacon.

When you intercept the desired inbound bearing to the beacon, actually just shortly before that point, you make another 45° turn, this time toward the airport, nicely rolling out on the specified track back to the beacon.

The approach plate defines the direction of the procedure turn from the outbound track. There is no freedom in that: what the chart shows is mandatory.

Approach—Profile

Considering the approach again, the aircraft flies outbound, tracking 327° from the NDB. Notice the underlined 2000 in the profile view. That indicates that the aircraft may not descend lower than 2000 ft MSL while outbound and in the procedure turn.

Once the aircraft is inbound, tracking 147° to the beacon, it may descend further, but no lower than 1300 ft. until it reaches the beacon, also referred to as the FAF or Final Approach Fix. From that point it may begin its descent to the MDA, or Minimum Descent Altitude, which is discussed on the next part of the approach plate.

The heavy line to the right of the beacon signifies the runway. Here, it is 3.7 nm from the beacon, a crucial number to know in a non-precision approach, where distance is gauged by time.

How low can you go? What are the minimum visibility requirements? Read on.

Minimums

The minimums table is immediately below the profile view.

Note that approach plate lists only the first four categories.

The next two rows list the minima for the two possible types of landing with this procedure: Straight in to runway 14 (S–14), or Circling to land at any of the other available runways. A Straight landing is defined as one where the approach course is aligned within 30° of the runway heading.

The straight-in landing minima at Millville for runway 14 is 520 ft. Minimum Descent Altitude (MDA) and one statute mile reported visibility for Categories A and B aircraft. The MDA remains the same for C and D, but the visibility minimums increase to 1¼ and 1½ statute miles respectively.

MDA is exactly as the words say. The aircraft may not descend below the Minimum Descent Altitude during an approach unless the approach-end of the runway is firmly in sight, and a safe, normal visual landing can be made. No diving to the runway hoping to touchdown on the last quarter of its length.

Ignore the numbers in the parenthesis; they apply to military aircraft only. The small numbers just before the parenthesis is the actual height of the MDA above the airport. This may not be the mathematical subtraction of ceiling and field elevation, because field elevation and airport height can differ by several feet.

Note that the landing minima for a circling approach are generally higher than for a straight-in approach.

Airport Plan View

This view gives the pertinent details of the runways; their length and width, and the runway numbers. Note the "TDZE 82" for Runway 14. That is the Touch Down Zone Elevation for Runway 14. Recall in the minimums table that for the S–14 approach with an MDA of 520 ft, the height above the airport was shown as 438 ft? That was obtained by subtracting the 82 ft TDZE from 520 ft MDA.

Recall also on the plan view of the approach, that three runways were in the little diagram at the end of the approach arrow? The airport plan view shows that runways 10–28 and 14–32 are available. A third N–S runway is shown as closed–denoted by an "X" at either end.

The airport plan view also reminds the pilot that Rwy 14 is 3.7 nm from the FAF, Final Approach Fix, which is the NDB, and that the approach course is 147°.

At the bottom of the view is the runway lighting information. Here MIRL, Medium Intensity Runway Lights, are available on both runways and are pilot controlled.

The Black circle with a white "5" inside of it near Rwy 10 indicates the type of lighting. A white letter in a black circle denotes that the lights are pilot controlled. The dot at the top of that black circle indicates sequenced flashing approach lights–called "the rabbit" by pilots because they chase it down to the end of the runway.

If the airport is large, its plan view occupies an entire page of the approach plate booklet.

Time from FAF to MAP

Distances in a non-precision approach are gauged by measuring time. The critical time of a non-precision approach is from the FAF, or Final Approach Fix (the NDB) to the MAP, Missed Approach Point, or touch down zone of the runway. The times to cover this distance, 3.7 nm here, are calculated and entered into a table located below the airport plan view.

It would be nice if our aircraft, considering any wind component, approached the MAP at a speed exactly listed in the table. Seldom happens, so interpolation is needed. Assume you approach in your Barn Burner at 75 knots, midway between two entries in the table. Recalculate for your 75 kt approach speed, 2 min., 58 sec., and jot that time down on your clipboard so that it will be available when you run the approach. Don't want to be doing those calculations at the final moments of the approach.

It's time to fly the approach. Click on the NDB off Airport button to get into the soup and see if you can find the runway.

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