• How To Fly An NDB Approach

    How To...Fly An NDB Approach

    By Neville van Eerten (6 March 2002) RMIThis tutorial is to assist pilots in the correct way to make a NDB approach into an unattended aerodrome in Instrument Meteorological Conditions (IMC).


    1. Overview
    2. Initial approach
    3. Entering the Hold
    4. Procedure turn
    5. Making the Approach
    6. Circle to land
    7. Missed approach


    Approach Plate

    In this tutorial we will make an approach into the Ashburton aerodrome in South Canterbury, New Zealand which is 40 miles south west of Christchurch International.

    The surrounding area is the Canterbury Plains, though there is a mast at 828 feet within 10 miles of the aerodrome.

    We will enter the hold from the East. Once established in the hold we will commence the procedure turn (labeled 074°), turn L to capture the 209° track inbound for the NDB, then continue outbound on the 209° track decending to just above 1500 feet on base turn. After 2 minutes we will make a slow R turn to join the 011° track inbound for the NDB, then either commence a Circle to Land or a standard missed approach by tracking outbound on the 099°, then a R turn back to the Ashburton NDB at 2000 ft.

    We are flying ZK-PFT which is a a light twin. This is a Baron in FS2002, and the aerodrome is uncontrolled.

    Initial Approach

    PFT: Ashburton Traffic, Papa Foxtrot Tango is 15 east of the field at 4000, entering the hold at 2000.

    You have communicated on 119.1 to everyone in the vicinity that you are currently at 4000 feet and that you are entering the hold at 2000 feet from the east. Reduce your Manifold Pressure to 20 inches, while keeping your RPM at 2400.

    Check your ABRIEFS

    A = ATIS note especially NZCH QNH for your remote QNH calculation (see below)

    B = Brief the plate

    R = Radios - keep NAV 1 and 2 on NZCH 115.30, and ADF to 254 - check the Morse code ID

    I = Instruments

    E = Engines - temperatures and pressures etc. - mixtures to rich

    F = Fuel - sufficient

    S = Security - time to buckle up

    This is the Brief which you say out loud:

    NDB approach Ashburton Elevation 298, enter the hold at 2000 feet or higher (what the line below 2000 means), parallel entry, R hand inbound course 029°, procedure turn outbound 074° for 45 seconds, inbound on 209°, outbound for the approach on 209° for 2 minutes not below 1500 feet until established 011°. Cat A Circle to land MDA is 925 feet (see later for calculation) 2000 meter visibility, missed approach point is the beacon in a climbing R turn, intercept track 099°, turn right and climb to the 2000 foot holding altitude.

    What a mouthful, but exactly what you should do - a very good reason to do it earlier. It will implant it into your mind. Go through the plate and see what everything means until you can do it by heart yourself.

    Make sure you have tuned your NDB to 254 and ALWAYS check that you have the correct one by checking the Morse code whenever you change ANY frequency.

    Now check your NDB needle to see what track the NDB is on, and try to keep the needle pointing on that track (probably around 290 degrees).

    Remember: "Push the head, pull the tail."

    RMIIf you are going towards the NDB and the needle is swinging down to the R, then you will have to turn past the needle and push it back

    For example here you are flying on a heading of 105° and the NDB is at 115°. (Disregard the thicker needle for this example.) If you continue flying like this (in a no wind situation) the needle will drop to the R (south) and you will fly to the L (north) of the NDB. To follow the 105° track to the NDB, you would have to fly 125° to 135° until you pushed the head to 105° then you can fly heading 105° again.

    It is generally expected that you can hold an NDB within 5 degrees of an intended track. If it was the tail then you would pull the tail around to the correct track FROM the NDB.

    Entering the Hold.

    Have a look at the right hand side of the approach plate. I would also suggest that you look at the hold tutorial for the different type of entries into a hold.

    Holding PatternYou will see some radials marked out for you. We are making an entry from the east on the 110° radial (heading 290°). This means that we will be making a parallel entry - the slashed path between the 209° track and the 319° track. So you will pass overhead the beacon on your present heading for 10 seconds, then turn L onto a heading of 209°.

    PFT: Ashburton Traffic, Papa Foxtrot Tango overhead the beacon 2000 ft entering the hold.

    After 60 seconds (time it), you will make a 25 degree bank L turn (steeper than normal) to join the 029 inbound track.

    When over the beacon:

    PFT: Ashburton Traffic, Papa Foxtrot Tango established in the hold 2000 feet.

    Now you just follow the track one-minute legs. Again check out the Hold Tutorial to know if you are on track or not. Remember to time from when the NDB needle is at R angles to the 209° heading you are on. Make nice smooth 20 degree R banks, never past 30 degrees in IMC. Turn out to follow the 029° track inbound for the NDB. You can keep circling as many time as you like (trying to figure out where the wind is coming from and adjusting for it as per the Hold Tutorial. Each time you cross the beacon:

    PFT: Ashburton Traffic, Papa Foxtrot Tango established in the hold 2000 feet.

    Procedure TurnProcedure Turn

    OK, we are bored of going around in circles. We have figured out where the wind is coming from and we are approaching the beacon on the inbound leg of the hold (029° track).

    PFT: Ashburton Traffic, Papa Foxtrot Tango overhead the beacon 2000 ft commencing procedure turn.

    We are going to maintain 2000 feet and turn R to join the 074° track. To do this we will need to turn past 074° to say 104° heading, until the needle rises to 074°. You hold this for 60 seconds (75 seconds in a Cat C or D e.g.. Boeing 737, 777). Commence your L turn back onto the reverse direction of 254° heading, to capture the 209° inbound track for the NDB. Remember try and keep within 5 degrees of the track.

    The closer you get to the NDB the smaller the heading adjustments should be to keep on track.

    Making the Approach

    PFT: Ashburton Traffic, Papa Foxtrot Tango overhead the beacon 2000 ft outbound for the NDB Approach.

    A couple of things to note: First, there is no need to communicate the altitude information as it is a standard approach. Secondly, unless there is an ATIS at the aerodrome you are using, you will need to use Remote QNH for your Minimum Descent Altitude (MDA). This means you need to use the QNH from Christchurch and make a safety alteration. The calculation is as follows:

    After the first 5NM you add 5 feet per NM for a safety barrier of (5 (feet) x (40 (NM) -5 (NM))) = 175 feet.

    Ashburton is 40NM from NZCH so the MDA for a Cat A approach is: 750 feet + 175 feet = 925 feet which is our adjusted Minimum Descent Altitude. The reason for this is to give a safety barrier to prevent you from hitting an object.

    Time to slow the plane down and do your downwind BUMF checks. (Shortened a bit)

    B = Brakes - nothing more embarrassing than a slide into a fence

    U = Undercarriage - three green lights

    M = Mixtures rich - full rich

    F = Fuel - fuel pumps on, landing lights on

    Approach DiagramWhen you are over the beacon you start your timer and time for two minutes, at the same time decending down to not less than 1500 feet.

    Slow to 110 knots by reducing the Manifold Pressure to 10 - 18 inches. Always keep above the blue line on your ASI, until you are flaring for the landing. At around 1 minute, lower the first notch of flaps and then lower your landing gear. After two minutes:

    PFT: Ashburton Traffic, Papa Foxtrot Tango turning base for the NDB approach.

    Make this a 15 degree angle of bank, as you are two minutes out from the beacon. You need to turn to be inbound between 006° track and 016° track (5 degrees each side of 011°) for the inbound approach. You cannot continue your descent until you are inside those parameters. Once you are inside those parameters, then you can report established, and continue your descent to just above the MDA of 925 feet.

    PFT: Ashburton Traffic, Papa Foxtrot Tango final, NDB approach.

    Now lets get these CUP checks done:

    C = Cowl Flaps - open (if applicable to your aircraft)

    U = Undercarriage - three green lights

    P = Pitch - full fine

    Now those motors are screaming, waking up everybody in a 2 mile radius

    If you reach the NDB without becoming visual at MDA, or slip outside the 5 degrees each side of the 011° inbound track then you MUST do a Standard Missed Approach.

    Circle to Land

    You're visual, and the aircraft should be at your 11 o'clock to 7 o'clock position depending on how close you are to the beacon. Note that you are not lined up for a particular runway so you need to perform a Circle to Land approach, so you can land on the runway in use using your usual uncontrolled aerodrome calls. Don't forget the following checklist when on short final.

    W = Wheels - yes, the third time I checked the wheels for three green lights

    W = Windsock

    Missed Approach

    When you are at the Missed Approach Point (the NDB) at the MDA (925 feet) if you are still in the clouds, or the visibility is less than 2000 meters, or you are not on the 011° final track (+/- 5 degrees), you must perform a Standard Missed Approach.

    This is depicted by the slashed line on the chart.

    Make a climbing R turn onto a heading of 129° to intercept the 099° track. Get the landing gear and the flaps up. Landing lights and fuel pumps off. Manifold pressure to 25 and RPM to 2500, then give your radio call.

    PFT: Ashburton Traffic, Papa Foxtrot Tango commencing missed approach.

    It is time to contact Christchurch Control if you are going back to Christchurch. Keep Comm 1 on 119.10 so you can listen to local traffic and transmit on Comm 2 to Christchurch on 120.90.

    PFT: Christchurch Control, Papa Foxtrot Tango missed approach Ashburton, requesting onwards to Eyrewell 3000.

    You have told them that you are on the missed approach point and that you want to enter controlled airspace again to Eyrewell VOR at 3000 feet.

    You are now tracking the 099° track and have been outbound for 60 seconds, so make a right-hand turn back to the beacon. Do NOT go past 2000 feet, as the Missed Approach requires you be at exactly 2000 feet on area QNH. If you do not hear back from Christchurch by the time you reach Ashburton then you MUST enter the hold (probably a parallel entry as before).

    Thankfully, ATC knows what you are doing and gives you onwards.

    ATC: Papa Foxtrot Tango you are identified, cleared to Eyrewell 3000 feet, report approaching Eyrewell, Christchurch Control.

    So now you can continue your climb to 3000 feet. Now transmit on 119.10, but keep listening to 120.90.

    PFT: Ashburton Traffic, Papa Foxtrot Tango climbing to 3000 for the NDB.

    Once over the beacon, you say:

    PFT: Ashburton Traffic, Papa Foxtrot Tango overhead the beacon, tracking direct Eyrewell 3000 feet, vacating north.

    Congratulations on passing one of the most difficult of approaches. If this is your first approach and you are successful, then ILS and other approaches will be a breeze.

    Neville van Eerten
    [email protected]

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