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VOR Approach

Gulfstream G450 Instrument Procedures

The VOR approach used to be the staple of instrument flying, the "go to" approach for airports too poor to afford and ILS. Now most of those airports are opting for the far more accurate and, well, cheaper, RNAV (GPS) approach. Flying the VOR approach became very easy for a time, but with the disappearance of the overlay program, not so much any more.


 

Approach Category

If you have ASC 007 you are a Category C airplane unless you have a maintenance logbook entry raising your maximum landing weight. If you do not have ASC 007, you are a Category D airplane, end of discussion. See G450 Approach Category for an explanation.

Approach Selection

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Photo: MCDU arrival page (KASH), from Eddie's aircraft.

Approach selection is made either through the MCDU (NAV > ARRIVAL) or the NAV display.

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Photo: MCDU arrival page (KASH), from Eddie's aircraft.

There is an advantage to making this selection on the NAV display: if the appropriate chart is selected in green from the CHARTS page, future changes to the approach on the NAV display will automatically change the selected chart.

Automatic NAV Preview

The FMS will not automatically preview a VOR approach.

VOR Mode Selection

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Figure: LNAV Mode Selection, from G450 Aircraft Operating Manual, §2B-08-00, Pg. 7.

Approach Armed

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Figure: VOR Mode Arm, from G450 Aircraft Operating Manual §2B-08-00, Figure 8.

[G450 AOM, §2B-08-120 ¶6.] The VOR mode automatically intercepts, captures, and tracks a selected VOR radial using the selected navigation source displayed on the coupled PFD. The VOR navigation source is selected using the display controller (NAV 1, NAV 2, or NAV 3). The radios are then tuned, the desired course is set, and the heading bug is positioned for beam intercept. [The figure] shows an aircraft approaching into a VOR intercept.

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Figure: VOR Mode, from G450 Aircraft Flight Manual §2B-08-00, figure 7.

[G450 AOM, §2B-08-120 ¶8.] When flying a VOR intercept, the maximum intercept angle should be less than 45°. However, if the intercept angle is greater than 45°, course cut limiting occurs. Course cut limiting does not occur at close-in intercepts because the beam width (in NM) is small. The course cut limiter functions primarily when approaching the VOR radial at an intercept angle greater than 45° and at high speed. It limits steering commands so they are within 45° of intercept. This directs the flight path to the selected radial sooner, and prevents the aircraft from overshooting beam center. Typically, the roll command makes an initial heading change, levels out, and flies toward the beam. Then the roll command makes a second heading change to line up on the center of the selected radial.

VOR Course Tracking

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Figure: VOR Course Tracking, from G450 Aircraft Operating Manual §2B-08-00, Figure 10.

[G450 AOM, §2B-08-120 ¶7.] When the aircraft reaches the lateral beam sensor (LBS) trip point, the FGC automatically drops the heading select mode and switches to the VOR capture phase.

References

Gulfstream G450 Aircraft Operating Manual, Revision 35, April 30, 2013.

Gulfstream G450 Aircraft Service Change 007C, Maximum Landing Gross Weight, 58,500 pounds, Category C, Provisions, October 26, 2011

Revision: 20131104
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