How to…. Fly a Hold

by Jacques Zahar, CFI

(Note this page is best viewed with a 1024X768 resolution)

 

Basically, a Hold is for airplanes like a stoplight for cars. Except that you can’t put the parking brake on in flight….

 

The purpose is to have the plane wait at a specified part of airspace (“Protected airspace”) until the traffic ahead of your plane is far away enough or has landed.

 

Though Holding instructions are seldom ever used under the Procontroller/Squawkbox virtual ATC environment, on very congested areas (Fly-ins) or simply for practice, it can be interesting both for ATC and Pilot if Hold is accepted and flown.

The purpose of these pages is to give Virtual Pilots a way to fly a Hold manually.

 

This section will be divided into 4 sections:

 

1-     Holding Clearances: How to decipher holding clearances

2-     Types of entry: Depending on your location, how to enter a holding pattern properly

3-     Flying a Hold: Principles of holding

4-     Exiting a Hold: What to do next?

 

Before having a look at holding clearances, let’s see the basic elements of a Holding pattern :

 

Without crosswind, a Holding pattern is like a racetrack:

See the arrows? They indicate the turn direction. A holding pattern with right turns is called a standard hold, one with left turns is called a non-standard hold. This is important to know, as some ATC can say “standard” instead of “right turns” or assume that the hold will be standard if they don’t specify the direction of the turns.

 

See also the inbound leg: this is the leg to which ATC refers to when giving the clearance, it is always going to and  finishing at the holding fix. The inbound leg should be flown for ONE minute if below 14000 feet or ONE ½ minute if above 14000feet unless otherwise specified.  The outbound leg is not timed and depending on the wind can take more or less time than the inbound leg.

Note that ATC can also give DME Holds, in which case ATC will specify the distances from the navigation aid at which the inbound and outbound legs are to be terminated. In this case no timing should occur, since the DME distances given describe the end of the inbound leg and the start of the turn outbound, and the end of the outbound leg and the start of the turn inbound.

 

Last, look at the turns. No radius is specified here since they are all standard rate turns (3° per second) in a hold. It’s time to use the small airplane of your turn coordinator !

 


 

 

1-    Holding clearances:

Note that not all holds are issued by ATC. One can have to hold without specific instructions if the last point you have been cleared to is reached without further ATC instructions (ATC is sometimes busy…) or when communications have been lost. In that case use a standard pattern (right turns) upon reaching the last assigned fix.

 

ATC issues holding instructions in the following form:

-         Geographical reference of the Holding fix: the general location of the holding

-         Inbound leg: the inbound leg is always the reference

-         Turn direction: (right turns (standard) or left turns (non-standard)

-         Altitude

-         Expected further clearance time (EFC)

-         Current time (optional)

 

For example: “C-GSRW, hold north-west of the Mirabel VOR on the 330 degrees radial, left turns, maintain 5000 feet, expect further clearance at 1730, time is 1712”

 

“hold north-west…”

The general direction of the holding pattern’s inbound leg in reference of the holding fix, using geographical directions (N, NE, E, SE, S, SW, W, NW,)

 

“the Mirabel VOR..”

The holding fix. This can be a VOR, an NDB, or a Fix (intersection)

or even a Marker beacon.

A holding fix can also be defined via DME distances,

in that instance a radial and DM

E distance are given.

 

“on the 330 degrees radial…”

The track upon which the holding pattern’s inbound leg is located

 

“left turns…”

Obvious. Note that the turns used to enter the hold are not considered.

Once you are established in the hold, all your turns will be as instructed,

in our case this one is a non-standard pattern.

“maintain 5000 feet…”

the assigned altitude

 

“expect further clearance at 1730..”

the expected departure time from the holding fix.

This doesn’t necessarily means that you’ll be leaving the hold at that time (ATC can release you earlier at anytime), but in case of lost radio communications during the hold, you are expected to hold until the EFC and proceed as filed or land if it was planned. So before accepting a holding clearance (by reading  it back), always check your remaining fuel and NEVER accept EFC that can compromise your fuel reserves and alternate airport requirement.

 

Note: sometimes ATC can issue abbreviated holding instructions, if the hold is published on the HI/LO maps or the approach plates. In that case it will simply say “as published” or “as charted”.

 

Okay, we’ve copied and readback the holding clearance, now it’s time to figure out where  and how to enter this pattern.

 

1-The first thing to do upon receiving an holding clearance is to check the EFC against the remaining fuel.

 

2-The second is to reduce airspeed if you are within 3 minutes of the holding fix or ask the ATC for a speed reduction if you are further than 3 minutes. Holdings are here to have you to wait, so why not reduce your speed ASAP and save fuel at the same time? If you’re lucky, by the time you have reached the holding fix at reduced speed, the hold won’t be needed anymore!

 

Propeller aircrafts(including turboprops)

175 Kts IAS

Civil turbojets

230 Kts IAS below 14000ft

265  Kts IAS above 14000ft

Military turbojets

265 Kts IAS

Climbing in holds

310 Kts IAS or less (jets)

Moreover the extra time will help you figure out where you are from the fix, and how to enter the holding pattern.

There is a holding speed limitation in a Hold, based on the following limitations (Note: this is based on Canadian regulations, check your local ones).

IAS stands for Indicated airspeed, in knots.

 

 

 

 

3-The third thing is to fly direct the holding fix, in order to become oriented and set-up the entry procedure.

Here’s an easy way to visualize where is the Holding pattern considering your position, by using your directional gyro (DG) or your Horizontal situation indicator (
HSI) :  The Holding fix is located at the centre of the DG or your HSI, and you are at the bottom of the instrument heading toward the fix. Now locate the radial or bearing from the holding fix on the HSI: this is the inbound leg. Then visualize the racetrack according to the type of turns.

  

 

 

 

 

 

 

2-Types of entry:

Once we figured out where is this holding pattern, let’ talk about types of entry.

 

There are three types of entry, depending on your location when approaching the holding fix.

Divide the airspace in two parts along the inbound leg of the hold (1), then at right angle starting from the fix (2). Lastly, tilt the line N°2,  20 degrees down to the side of the holding pattern (3).  You end up creating four sectors (actually three) which give you the type of entries required.

 Direct Entry

 Parallel Entry

Teardrop Entry

Since we visualize the holding pattern directly on the DG or HSI, the entry method and the headings to follow become straightforward.

In our last example  (a nonstandard holding pattern on the 330 degrees radial), we would have to fly a teardrop entry, i.e. fly direct to the fix from the South with a 360 heading, then upon passing the fix (the VOR flag changes from TO to FROM), we fly the 360 degrees heading (330 degrees PLUS 30 degrees ) and start the timer for one minute, then turn left (standard rate turn) to intercept and track the 330 radial of YMX VOR and enter the hold.

Let’s say we are heading from the West in a 090 heading. This time we have to perform a direct entry, i.e. we fly direct to the fix with a 090 heading, then upon passing the fix (the VOR/HSI flag changes from TO to FROM), we turn outbound on the 330 heading with a standard rate left turn. When  we level off the turn, we start the timer for one minute, and then we go. At the end of one minute (plus or minus the wind correction), we start the turn to intercept and track the 330 radial inbound and enter the hold.

Here we are flying direct the VOR from the East on a 240 heading. Our position calls for a parallel entry, i.e. we fly direct the VOR with a 240 heading, then upon passing the fix (the VOR/HSI flag changes from TO to FROM), we turn right to a heading 330 so we fly parallel to the inbound course and start the timer for one minute, then  turn right (notice the difference with the other type of entries) to intercept and track inbound the 330 radial and enter the hold.

 

Practice a little bit using this method and avoid drawing anything on a piece of paper. When you’re flying in the clouds your eyes should be on the instruments and seldom elsewhere!

The trick is to VISUALIZE and PRACTICE.

3-Flying the hold

Now it’s time to relax and let the autopilot do the job… No just kidding, unless you fly one of these all-computerized FMS machines that can do a Hold with a simple couple of keystrokes…

 

Once you’ve entered the Hold either way, you should be flying inbound the fix, tracking the VOR radial or the NDB inbound course. You have to remember that a Hold is (in most cases) one minute long on the inbound leg when below 14000feet or 1 ½ minute when above 14000feet.

 

In order to reach that goal, and keep the ATC happy, we have to account for the wind. We will have to compensate for headwind or tailwind by adjusting the outbound leg so the inbound leg is one minute or one ½ minute long.

 

When to start the timer?

 

*  For the inbound leg:

- As soon as you roll out from the inbound turn out OR intercept the inbound track, start the timer.

- When abeam the station at a VOR (the flag changes from TO to FROM) or a NDB (The needle flips from the nose to the tail), stop the timer.

*  For the outbound leg:

-If the Holding fix is a VOR, when the TO-FROM indicator changes from FROM to TO, start the timer.

-If the holding fix  is a NDB, when the needle points (with no wind) 90 degrees to the left or the right, i.e. points to the wingtip, start the timer.

Turns are never timed, as they are standard rate turns.

You end the outbound time and start the inbound turn depending on the wind.

Adjusting the outbound leg.

 

If you don’t know the winds aloft, fly the first pattern with a one minute outbound leg. Then measure the time required to fly the inbound leg. For the second pattern, fly the outbound leg  by adding or substracting to one minute the difference between one minute and the time you flew the inbound leg. Confused? An example will make it clear.

*  If the first outbound leg was 1 minute and the inbound leg took 30 seconds, fly the next outbound leg for  1 ½ minute (60sec+30sec). (Headwind on the outbound leg, see the example below)

*  If the first outbound leg was 1 minute and the inbound leg took 1 minute and 15 seconds, fly the next outbound leg for  45 seconds (60sec-15sec). (Headwind on the inbound leg)

Wind correction and Crosswind.

In a perfect world, there would no be crosswinds. But in real world (and even in simulation!) the crosswind is something to be accounted for in a Hold.

 

Since both turns are standard rate, a crosswind causes the downwind turn to have a larger radius than the upwind turn.

So the racetrack looks now more an egg shaped oval when crosswind is involved.

Now you have your answer ready when ATC calls in and ask the reason for the strange pattern you’re drawing on his scope!


So obviously one have to fly the pattern while correcting for the wind.

 

The rule of thumb is to “double the inbound leg wind correction angle on the outbound leg”.

 

On the inbound leg, track the VOR radial and use whatever correction angle is needed to compensate the drift and stay on course. Note the wind correction angle you are using.

So if you had to fly a 100 degrees heading (1) to stay on course inbound of a  270 radial (90+10 degrees wind correction angle), in order to compensate for a crosswind coming from your right, you will fly a 250 degrees heading (2) outbound (270-(2*10 degrees)) for the outbound leg.

4-Exiting the hold

After a couple of turns, the ATC will probably release you from the hold (at last!)

But if you’re five minutes from the EFC time, ask the ATC for a clearance (he’s probably asleep…), as you need to know what to do next. He will then clear you for another Hold (oh nooo!), have you descend to another altitude and hold(Shuttle Hold, more on that later), or give you radar vectors to proceed direct to the approach.

 

In case of radio communication failure, squawk 7600, hold until reaching the EFC time, then proceed as filed, i.e. fly the full approach or proceed to the next waypoint on your route.

In all cases, try and adjust your speed so you leave the Holding pattern as close as possible as the EFC time you’ve been given in the holding clearance.

Shuttle procedure.

A shuttle procedure is a maneuver involving a descent or climb in a pattern similar to a holding pattern. It is used on instrument procedures located in mountainous areas, or for certain types of missed approaches, or when ATC clears a plane, located below in a stack, for the approach and instructs the planes holding in the same airspace to descend one step further.

 

The maneuver is flown exactly the same as a holding pattern, except that descent will occur within the inbound or the outbound leg. In order to prevent the airplane from exiting the protected airspace, speed is restricted to 200kts IAS.

 

 

Enjoy the flight!

Jacques Zahar

ICAO CPL/ multi/IR flight instructor

 

The material exposed here is copyrighted and should not be used without written permission from the author.

For comments or suggestions write to Jacques Zahar.