EASy Avionics: Everything You Ever Wanted to Know About Vertical Navigation

Select the Prior to JOH radio button (this will automatically check the Past/Prior to box), since the ATC clearance was the cross 50 miles southeast of JOH, i.e. prior to it since the aircraft is approaching JOH from the southeast. Next enter 50 in the NM box using either the multifunction keyboard (MKB) or dual-concentric knob on the CCD. Finally, select the At radio button and enter a crossing altitude of FL300 (the Altitude box is also automatically checked). Figure 2 shows the Cross JOH dialog box after this information has been entered.

Selecting the Apply button creates a change to the pending flight plan with a top of descent (TOD) point such that the descent angle into the new pilot-defined waypoint is 2.6 degrees, which is the default angle defined on the Auto Speeds tab of the Avionics window (Figure 3).

There are times when it might be desirable to use a different descent angle into a crossing restriction. For example, if a descent is to be made through a cloud layer with known or potential turbulence, a steeper descent angle might be desired to minimize passenger discomfort. To do this, simply select the Angle checkbox in the Cross dialog box and enter the desired descent angle into the waypoint. In the example shown in Figure 4, 3.5 degrees is entered to steepen the descent path and move the TOD further ahead of the aircraft.

Select Apply, then activate the modified flight plan. The new pilot-defined waypoint of 50 NM prior to JOH is then displayed in the waypoint list as *PD01, as shown in Figure 5. The “PD” portion of this new waypoint label means it was defined using the Place-Distance method, 50 NM (distance) prior to JOH (place). The “01” means it is the first pilot-defined waypoint of this type to be entered into the waypoint list.

The crossing restriction of FL300 that was entered in the Cross dialog box can be seen to the right of *PD01. The descent angle of 3.50 is also shown in white to indicate it was manually entered into the Cross dialog box and will override the default angle of 2.6 degrees. The predicted vertical speed required to comply with the 3.5 degrees descent angle is shown in green above the white 3.50; in this case, 2,900 feet per minute.

Example 2

Let’s look at a similar but different example using a pilot-defined place-distance waypoint. The waypoint list for this new example is shown in Figure 6.

ATC now issues the clearance “Cross 130 miles northwest of DUGGS at flight level 300.” In the same manner as the previous example, click on DUGGS, open the Cross dialog box, select Past DUGGS and enter 130 NM, as shown in Figure 7.

However, once the distance is entered, the CHECK *PD PLACEMENT message box appears (Figure 8). This message is an alert to tell the pilot (based on the offset distance entered) that a waypoint on the flight plan exists between the reference waypoint (DUGGS) and the newly defined place-distance waypoint.

Looking back at Figure 6, the distance of the flight plan leg past DUGGS is 110 NM (the distance from DUGGS to HANRY). Our pilot-defined waypoint was defined as 130 NM past DUGGS, which is 20 NM past HANRY. Therefore, the “CHECK *PD PLACEMENT” message was displayed. But fear not because, unlike some older FMS versions, the EASy FMS will handle the logical placement of the waypoint and properly insert it into the waypoint list.

After selecting OK to acknowledge the message, enter an altitude constraint of FL300 into the Cross dialog box (Figure 9), then click Apply.

The pending change to the flight plan is displayed in cyan in the waypoint list. Since we received the message earlier to check the *PD placement, extra attention must be given to the waypoint list items prior to selecting the Activate soft key. The total distance from DUGGS to *PD13 should be verified that it equals 130 NM (in this example, it totals 130.2 NM due to the magnetic variation over the long distance of the course). Next, the flight plan courses should be checked to ensure straight-line continuity. Finally, the restriction of FL300 should be checked prior to selecting Activate (Figure 10).

Example 3

ATC now issues an amendment to our routing: “After the ANN VOR, fly the 350 radial to 25 DME, then direct PANC.” Since the route amendment is after the ANN VOR, use the CCD to select ANN in the waypoint list, then select Amend Route from the task list, as shown in Figure 11.

Next, type ANN/350/25 to create a pilot-defined waypoint using the Place/Bearing/Distance (P/B/D) method (Figure 12). This corresponds to the reference place (ANN), the bearing from ANN (the 350-degree radial), and the distance from ANN (25 DME).

Push Enter on the MKB to move the P/B/D waypoint into the pending flight plan. It is displayed as *PBD04. The “PBD” portion of this new waypoint label means it was defined using the Place/Bearing/Distance method; the “04” means it is the fourth pilot-defined waypoint of this type to be entered into the waypoint list.

A pending flight plan change is created. Review the placement of *PBD04 on both the INAV and the waypoint list, then activate the change by selecting either of the cyan Activate softkeys shown in Figure 13.

While such an ATC clearance to cross this newly created fix would be rare, the Cross dialog box can be used to define a crossing restriction for *PBD04, should it be required. Note that the “Past/Prior to” selections are not available for use in reference to this type of waypoint.

Example 4

The last example of creating a pilot-defined waypoint is the Place/Bearing/Place/Bearing method. This method is used to comply with a clearance to a fix that was defined by the crossing of two radials or bearings from two different fixes.

Let’s say that after the ANN VOR, we needed to proceed directly to the intersection of the ANN 350-degree radial and the AKW 090-degree radial. Just like in the previous example, select ANN from the waypoint list, then select Amend Route (Figure 11, above). Next, type ANN/350/AKW/090 to create a pilot-defined waypoint using the Place/Distance/Place/Distance (P/D/P/D) method. This corresponds to the first reference place (ANN), the bearing from ANN (the 350-degree radial), the second reference place (AKW), and the bearing from AKW (the 090-degree radial).

The new waypoint is inserted into the flight plan as *RR01. The “RR” portion of this new waypoint label means it was defined using the Place/Bearing/Place/Bearing (or Radial-Radial method); the “01” means it is the first pilot-defined waypoint of this type to be entered into the waypoint list. Review the placement of *RR01, then activate the pending change.

Should a crossing restriction be required, the Cross dialog box can be used to add a restriction to the new *RR01 waypoint in a similar fashion as described in the previous examples.

This article (Part Three in the series) has introduced pilot-defined waypoints with crossing restrictions and the Angle option in the Cross dialog box. Future articles in this VNAV series will explore additional functions in easy-to-understand explanations. Be sure to “tune in” next time for more EASy VNAV information!