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Approach and Minima

Airport Approaches

The approach is the final segment of a flight that connects to the runway at the airport.  Before the existence of approaches in NFP, this segment was included as part of the STAR.  It is still possible to indicate that a STAR includes an approach so that the system does not try to add another approach on to the end of the STAR. If the STAR does not include an approach when the route is generated, the NFP system connects the STAR to the runway using an approach.

Similar to STARs, approaches include a series of waypoints with optional flight level restrictions.  They can be configured to be valid only during a given date and time range.  Approaches are considered common data and are maintained as part of the AIRAC cycle. Like airways, waypoints, and STARs, you cannot modify or add approaches. You can add criteria against a specific approach on the ALC Approach Minima screen.

Each approach will only be applicable for one runway at the airport however, multiple approaches may exist for a single runway.  While approaches are usually intended to be used at the end of a STAR, they can also be used without a STAR (a DCT route to an airport may still use an approach).

Minima

Approach Minima refers to the minimum ceiling and visibility required to use an approach.  When the route is being generated, the minima requirements help the NFP system determine the appropriate approach to use at an airport. The approach is not used if the ceiling and visibility at the airport do not meet the minima for the approach.  If the approach is specified in the route, a warning is generated to indicate that the selected approach is not valid.

Minima entries are keyed to a specific approach by its runway, type, suffix (if present) and transition ID.  Minima requires an approach speed category that tells the system which aircraft to apply the minima to. The minima will only apply to aircraft with the same approach speed category.

The Minima entry for an airport also includes a generic ceiling and visibility limit for Alternate use.  This means that when this airport is used as an Alternate, all approaches must meet the same minima.  The individual entries for each approach are used when the airport is used as a destination.

Approach Types

Approaches are categorized by type, this helps to  indicate which approach can be flown based on the aircraft’s equipment  set in FOMS 220.

Approach types are:

Description

Type

Localizer/Backcourse Approach

B

VORDME

D

Flight Management System (FMS)

F

Instrument Guidance System (IGS)

G

Instrument Landing System(ILS)

I

GNSS Landing System (GLS)

J

Localizer Only (LOC)

L

Microwave Landing System (MLS)

M

Non-Directional Beacon (NDB)

N

Global Positioning System (GPS)

P

Non-Directional Beacon + DME (NDB+DME)

Q

Area Navigation (RNAV)

R

VOR Approach using VORDME/VORTAC

S

TACAN

T

Simplified Directional Facility (SDF)

U

VOR

V

Microwave Landing System (MLS), TypeA

W

Localizer Directional Aid (LDA)

X

Microwave Landing System (MLS), Type B & C

Y

Missed Approach

Z

 

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Type

Description

Equipment Requirement

B

Localizer/Backcourse Approach

Item10 has S or L

D

VORDME

Item10 has O or S   AND  Item10 has D

F

Flight Management System (FMS)

 Item10 must be not N

Remove from default approach types

G

Instrument Guidance System (IGS)

Item10 has S or L

I

Instrument Landing System(ILS)

Item10 has L or S

J

GNSS Landing System (GLS)

Item10 has G

L

Localizer Only (LOC)

Item10 has S or L

M

Microwave Landing System (MLS)

Item10 has K

N

Non-Directional Beacon (NDB)

Item10 has F

P

Global Positioning System (GPS)

Item10 has G

Q

Non-Directional Beacon + DME (NDB+DME)

Item10 has F  AND Item10 has D

R

Area Navigation (RNAV)

Item10 has A or B or Item10 has R and Item18 has PBN

S

VOR Approach using VORDME/VORTAC

Item10 has O or S   AND  Item10 has T

T

TACAN

Item10 has T

U

Simplified Directional Facility (SDF)

Item10 must not be N

Removed from default approach types

V

VOR

Item10 has O or S

W

Microwave Landing System (MLS), TypeA

Item10 has K

X

Localizer Directional Aid (LDA)

Item10 has S or L

Y

Microwave Landing System (MLS), Type B & C

Item10 has K

Z

Missed Approach

None

Approach Types - FOMS 170

By default, approaches are turned on. In FOMS 170, set the Landing Approach flag to N to disable this feature. When set to Y or blank, the feature is on.

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Enter the sequence of approach types in order of preference if different from the default approach types hardcoded within NFP – IJPRDSVLBQNGXU. NFP looks at these when deciding on the best approach based on aircraft equipment (item 10).

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Set Default Runways flag to L/M/B/N. Option B ensures that the NFP system provides the best optimized option for the selected runway/approach type(s) available at the destination and/or alternate.

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Expanding an MTTA using Best Route generates the following result:

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Manual Route Building using Approach Minima

When building a manual route, the following string must be typed in the command box:

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In the route string shown above, here are the elements broken down:

YXU – STAR designator

APPROACH – tells the  NFP system that you want it to pick the best approach option based on aircraft equipment.

L – Approach type (Localizer only)
- - (double dashes) – this means that there is no suffix for the approach requested. If approach had a suffix, route string would be MTTA YXU APPROACH-L-A-LESAV RWY-08 CYKF

LESAV – Approach transition id - this is a unique identifier that usually matches the first waypoint of the approach but it does not have to be

RWY-08 – Runway for which approach is requested (must also meet suitability requirements)

Flight Plan Format – showing approach info

Here is an example of how you can show approach information in your format:

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Approaches - FOMS 326

FOMS 326 has been added as a new database for approaches. This database is updated every AIRAC cycle. You cannot add or edit FOMS 326. You can add criteria against a specific approach on the ALC Approach Minima screen.

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FOMS 326 Fields

Runway – Runway ID for which approach will be used

Type – Approach type (ILS, VOR, NDB, GNSS, etc……) – see approach type table

Suffix – Identifies same type approaches to the same runway – see example below

Disabled – Is approach disabled Y/N

Date/Time fields – allows user to restrict approaches on certain days and times

Usage – if set to “A” (ATC only), approach will not be available for flight planning – awaiting flight check

Here is an example of Suffix.

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Aircraft Category - FOMS 215

Each aircraft has an approach category that defines the approach speeds available for the aircraft.  The approach category can be set in FOMS 215 for the aircraft type or the Aircraft Characteristics menu FOMS 220 for an individual aircraft.

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ALC Approach Minima

The minimum allowable ceiling and visibility can be added for each approach.  This allows the NFP system to know whether or not an approach can be used with the current weather conditions at the airport. The MTTA attempts to try to avoid the approach if the minima are not met.  If an approach is specified and it does not meet the minima, a warning is generated.

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Ceiling value – entered as FL (hundreds of feet)

Visibility value – entered in meters (same as alert criteria)

Minima Type value - Select the applicable minima for the approach. When creating a new entry, the field will default to the value indicated below. Minima Types available include:

ILS 

CAT1 (Default), CAT1 LTS, CAT2, CAT2 OTS, CAT2 SA, CAT1 SA, CAT3A, CAT3B, CAT3C

Note: The aircraft's ILS capabilities (entered in FOMS 220 Aircraft Characteristics) will be compared to the minima type to evaluate approach suitability.  

LOC 

LOC (Default), LOC+DME 

VOR/DME 

VOR+DME (Default), VORTAC 

VOR 

VOR (Default), VOR+NDB, DVOR 

NDB/DME 

NDB-DME (Default), 2NDB-DME 

NDB 

NDB (Default), 2NDB 

RNAV 

LNAV (Default), LNAV/VNAV, LP, LPV, RNP 

RNP value - This field is available when the selected minima type is RNP. Enter the RNP precision value for the approach. The value is compared to the aircraft's RNP capability (entered in FOMS 220 Aircraft Characteristics) to determine approach suitability.

Missed Approach (MAP) Gradient value - Where the approach requires a specific climb gradient for obstacle clearance if a missed approach occurs, this value is compared to the aircraft's maximum climb gradient (entered in FOMS 220 Aircraft Characteristics) to determine approach suitability. This value is optional.

Note: The NFP system always looks for valid METARS first and if none are available for the destination (based on ETA), it looks at the TAF to determine whether the approach meets the approach minima.

Alternate Minima

Minima values for the destination alternate must be equal or greater than those entered for the airport.

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If a lesser minima value is entered, you will see this:

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