Holding
Courtesy of Andrew Ayers

Introduction by The Professor:
As usual, Andrew refers to X-Plane in his narrative. The technique he describes applies to any aircraft; real or simulated. If you fly offline, you'll never have to fly a hold, but you certainly can if you like. Flying on VATSIM however, you may frequently encounter holds depending on where you fly. In the UK for example, it is standard practice to assign a hold when descending on a STAR, then canceling it before entry if it is not needed. But you have to be prepared to fly it if not canceled. Andrew does his usual excellent job in teaching us the technique, and it's fun to learn. At the end of this lesson, you'll find a feature on how to use FSNavigator to assist with holding and an exercise to sharpen your skills. Enjoy!

Even though we never get assigned holds in X-Plane (and rarely in real life), it's a good skill to understand and be able to apply. Holds are very difficult to teach in writing, but hopefully, with the use of illustrations, you'll gain an understanding of how to properly execute a hold. Holds are basically circular patterns which keep aircraft in a small space, allowing ATC to keep traffic orderly and separated. In IFR training, we commonly practice holding over a VOR. Holds can take place in many places however. We can hold over NDBs, we can hold at DME distances on a specific VOR radial, we can hold at airway intersections, we can even hold at GPS waypoints with real-life GPS'. You'll frequently see holds plotted on approach plates and STARs. We'll simplify our discussion by just holding over a VOR and we'll also use a no-wind situation to start. I'll discussion wind correction afterwards.

Holds require that you be VERY familiar and comfortable with the operation of the VOR and interpretation of the NAV equipment. Because VORs have 360 radials, we can be assigned to hold on any of those. For our example, let's say that we have been told to hold east on the 090 radial of the Vero Beach VOR. So, we're going to head toward the VOR along the 090 radial, which means we'll be flying 270 TO. Standard holds are accomplished with right-hand turns, so when we pass over the VOR, we will make a 180 degree standard-rate turn to the right and head back away from the VOR for a specified time. We will then make another 180 degree standard-rate turn back towards the VOR. This will result in a racetrack pattern as depicted below.

You'll notice that we have an inbound (heading towards the VOR) leg and an outbound (a way from the VOR) leg. I've noted that the inbound leg should be 1 minute long. Above 14,000ft, the inbound leg should be 1 1/2 minutes long. So, how are we going to make sure our inbound leg is 1 minute long? Well, in a no-wind situation, our time outbound should equal our time inbound.

So, let's start as we pass the VOR inbound. We start our right 180 degree turn. As we reach the abeam (the holding fix) point, the TO/FROM flag will flip and we will start our timer. We'll then fly along until the timer indicates 1 minute and then begin our right-hand turn back inbound. If we make sure the turns are standard rate, we would roll right out onto the 090 radial (270 TO). At that point, we will again start our timer and see how long it takes us to reach the VOR. We do whatever it takes to make our inbound leg 1 minute long. If we found out that it only took us 50 seconds to fly the inbound leg, we would have to modify the outbound leg by adding 10 seconds to it, flying outbound for 1 minute and 10 seconds.

Now, let's talk a bit about how we navigate each leg. Since we're holding along the 090 radial, we will set 270 TO and TRACK the course inbound, keeping the needle centered. Now, as we approach the VOR, the needle will become more sensitive and start to move off-center. Don't chase it! Just continue to fly your heading until the TO/FROM indicator changes and then begin your turn. Now, as we turn outbound, what are we turning to? Well, since we're not tracking a radial outbound, we just turn to the reciprocal heading. So, in this case, we would turn to a heading of 090. The outbound leg is a dead-reckoning leg, we just fly a heading for a specified time (1 minute). So, like I said, if it was a no-wind situation, it would look just about like above.

You can see the various sectors for each entry. The sectors are determined by adding 110 degrees to the holding course on the non-holding side and subtracting 70 degrees from the holding course on the holding side. Our holding course is the 090 radial, so if we add 110 degrees, we get the 200 radial on the non-holding side and by subtracting, we get the 020 radial on the holding side.

We said above that we were proceeding inbound along the 230 radial, so by looking at the diagram, we see that we should make a teardrop entry. If we were inbound on the 330 radial, we'd make a parallel entry and so on. Now, let's take a look at what it looks like in the plane and from above. I'll be flying the situation we discussed above. In the first turn, I didn't fly outbound long enough, so I overshot the inbound leg. After we've looked at it, I'll discuss how to fly each entry.

OK, so now you've seen a teardrop entry. But how did I do it? Well, it's pretty simple. When you pass the holding fix, turn to a heading of 30 degrees less than your outbound leg heading. Since the outbound leg heading is 090, I turned to 060 degrees. You just fly outbound for 1 minute as usual and then turn inbound.

A direct entry is even easier. You simply fly as depicted. Once you cross the holding fix, you just begin your turn to the outbound leg heading. The parallel entry is the most difficult. As you pass the fix, you turn to the outbound leg heading, but you're flying parallel to the holding course on the NON-HOLDING side. After you've gone out for 1 minute, you then make a LEFT-HAND turn all the way back until you're heading direct to the VOR. Once you cross it, you proceed with the hold as normal.

OK, now let's talk briefly about flying in wind conditions and making crosswind corrections. On your first outbound leg in the hold, it's all going to be guess work since you haven't had a chance to establish a wind correction angle inbound yet. But, let's assume we're heading inbound along the 090 radial with a wind from the north at 20 knots. Because we have a crosswind, we're going to have to establish some crosswind correction to maintain course. I found that it was about 12 degrees to the right. So, since the outbound leg is a dead-reckoning leg, how are we going to compensate. Well, as we turn upwind, we're going to have a decreased groundspeed and as we make our turn back downwind, we're going to have an increased groundspeed. So, to account for that, we're actually going to have to fly AWAY from the course as we proceed outbound. To do this, we will DOUBLE our crosswind correction on the outbound leg. So, since I said it was 12 degrees, we will have a 24 degree correction outbound, or an outbound heading of 66 degrees. Below is a picture of what a properly executed hold with wind correction looks like. It appears odd, but it is the proper procedure.

Well, I hope this has helped you to gain an understanding of holding procedures. I'll mention a few other things. The maximum holding speed for all propeller-driven aircraft is 175KIAS. For civil turbojet aircraft, it is 200KIAS up to 6,000ft, 230KIAS up to 14,000ft, and 265KIAS above 14,000ft. For military turbojet aircraft, it's 230KIAS except for a few specific aircraft. Also, as I said above, normal holding take place with right-hand turns. You may be asked to hold with left-hand turns at times. In fact, the only time I was ever asked to hold outside of the training environment, I was asked to make left-hand turns. If they don't specify, you make right-hand turns. If you were instructed to hold east on the 090 radial of the VRB VOR at 7DME, you would follow the exact same procedure as above except that you would make your turns when you reach 7DME, not at the VOR. You should report to ATC when you enter the hold as well. You should be given an "expect further clearance" time so that you know about when you should be done holding or when to leave the hold in case of a loss of communications. As I said, holding can be complicated and a lot of people take a long time to pass this step in instrument training.

Altair VA Supplement - Using FSNavigator to plot and fly holds:
If you are using FSNavigator version 4 or above, you can use it to add a hold to your flight plan, either before you depart while creating the plan, or while in flight after instructed by ATC. I will assume you are familiar with flight planning and flying the flight plan, either manually following the track or coupled to the autopilot.

Use the mouse right-click menu to access the Holding Pattern option. From either a point on the map, a fix in the search window or a fix on the flight plan, right-click to bring up the menu. Select Holding Pattern. Specify the inbound course, direction of turns and length of leg. Note that you may select "inbound," which is the general direction of your flight, or "outbound." There is no such thing as outbound and you will never get such an instruction from ATC. Holds are always "inbound to a fix."

Pressing OK will plot the hold. If it's not what you intended, go back in on the fix and change it. You can have only one hold at a time in FSNavigator. Setting the hold will normally engage the "Fly Holding" button on the FMS tab. To exit the hold when ready, go to the FMS tab and disengage the "Fly Holding" button. Lastly, note that FSNavigator is not able to automatically fly legs less than 1.5 minutes and speeds greater than 180 knots (at least in version 4.5). You may want to uncouple the FMS from your autopilot to fly in conditions exceeding these parameters.

Exercise:
In this exercise, take the time to sketch out the course and holding on a piece of paper, or even better, overlaid on a sectional or IFR chart. You can also use FSNavigator. Draw the hold entry boundaries and identify the type of entry procedure for each sector. Clear all weather to start. Watch your altitude and airspeed. Fly the holds until you are precise with altitude, speed and track.

Depart KLGB, turning left direct SLI. I want you to hold east of SLI on the 120 degree radial, right hand turns, one minute legs (note this is the same as shown above except for direction of turns). Climb and maintain 4000.

Calculate the entry sectors. What entry should you use? Depends on the direction, but if you departed from runway 30 or the 25's and turned left, your heading is probably 60-100 degrees. Anything 50 to 120 would be a teardrop entry. Make that entry and establish on the hold. Adjust outbound leg length until you have a one-minute inbound length.

Fly at least two circuits, then depart SLI heading 300 degrees. A the 5 DME point, turn right and proceed direct SLI. Hold again east on the 120 radial, one-minute legs and standard turns. From this direction it will be a parallel entry.

Again fly at least two circuits, being as precise as possible with your track. Outbound, pause the sim and set winds to be 270 at 10 knots. Visualize how this wind will affect your ground track and prepare to compensate on the inbound leg. Some trial and error will be required, but as you determine the heading compensation to track the R-120 inbound, triple that correction angle on the outbound leg and continue to fly the hold until you have the angles adjusted for (1) A tight inbound track, and (2) One-minute inbound leg.

When ready, depart the hold and land KLGB.