Courtesy ofHal Stoen
Introduction by Gary Hader AAV 161:
This tutorial on "Holding" was written by retired corporate pilot, Hal Stoen. Hal incorporates his own experiences flying N1557G, a Cessna 421 Golden Eagle, into this lesson in a way that you will find not only informative, but entertaining as well. Enjoy !
Purpose of this tutorial
A discussion and tutorial on what "holding" is, why it is necessary, and how it is performed.
It was a dark and stormy night... No, it really wasn't. It was a blue-sky day, visibility was "forever" and we were level at FL230 (23,000 feet) in our company Cessna 421B,N1557G. We were enroute from our home base in Minneapolis to Dallas on a sales call to a new and, we hoped, future customer. "November1557 Golf, Kansas City." "57 Golf, go ahead Sir.""57 Golf, Kansas City. Fort Worth cannot accept you at this time. Hold at the Sheba intersection, as published. Maintain flight level two three zero. Expect further clearance at four five, time now zero two. Expect to hold about twenty minutes." "Understand hold at Sheba as depicted, maintain two three zero, expect further clearance at four five, five seven Golf."
What happened? First off, Fort Worth Center couldn't accept us because the air traffic controllers were on strike. Then, to further exacerbate the situation, the President of the United States fired the lot of them. Air traffic in the United States had decreased considerably, and, if you were a corporate operation like we were, you needed a reservation several days in advance to even operate in the system. I had my reservation (obviously),but the supervisors that were now operating Air Traffic Control could only work so many aircraft- Fort Worth Center had reached it's maximum. I would have to wait outside of their airspace boundary until another aircraft departed their jurisdiction before I could "come in."
What did all of that radio stuff mean? Let's discuss what "holding" is, and then we'll come back to the situation later in this tutorial.
Pilots hate to "hold"
They do, trust me. Pilots are members of the ultimate goal-orientated profession. Their job is to get from point A to point B, and as fast a possible, if you please. Ever watch some pilots taxi? Many carry more power than necessary and have to use the brakes just to keep slowing down. Impatient, that's what we are. And, once we get up into our element we really hate to "park it in the sky" and hold. It just goes against our grain.
What is "holding"?
Airborne parking. The aircraft is flown in a racetrack pattern, around and around, until there is space in the system for the aircraft to move on to the next segment of the flight.
Why does Air Traffic Control issue a "hold"?
For a variety of reasons. My situation in the Introduction was a little unusual, but I mention it to show that the procedure can be issued even under blue-sky conditions. Generally speaking, the normal reason for a hold being issued is that the receiver airport, your destination, is experiencing delays because of weather conditions. When the weather is below VFR (Visual Flight Rules)minimums, it means that all arriving aircraft have to fly the instrument approach(es) to that airport. This requires greater spacing between arriving aircraft and limits the capacity of the system.
Sometimes holding is done enroute, and sometimes it is done closer to the arrival airport. And, there is even a "ground hold". If the system is really backed up, Center will issue a "gate hold" while you are still on the ground. This saves on fuel as you can shut-down your engines and just monitor the radios until your clearance comes through.
At least you don't have to taxi around on the ground in a racetrack pattern.
What does a "holding pattern"look like?
Here's a typical holding pattern, along with the nomenclature that we will refer to in this tutorial.
A "Standard Pattern" is a hold using right-hand turns. A "Non-Standard Pattern" uses left-hand turns.
FIX The "hub" of the holding pattern. Everything in the hold is based on the Fix- time, distance, and navigation. The Fix may be an intersection, a VOR/VORTAC, a Marker Beacon, or a DME (Distance Measuring Equipment) distance on an airway, among others.
FIX END The end of the racetrack pattern that is near the Fix.
ABEAM When the aircraft is at a ninety right angle to the Fix.
HOLDING SIDE The outbound leg of the hold.
OUTBOUND END The end of the racetrack pattern that is farthest from the Fix.
HOLDING COURSE The course that the hold (along with the Fix) is predicated on. It may be a Localizer, an airway, or a VOR/VORTAC radial.
RECIPROCAL The opposite (180 degrees) of the Holding Course. For example, if the Holding Course is 270 degrees the Reciprocal will be 90 degrees.
NON-HOLDING SIDE The inbound leg of the hold.
"Non-Holding Side"? It looks like that term is reversed with the other one, the "Holding Side"
Yes, I agree. It has always confused me why the terms are the way that they are. You do all of your "adjustments" on the "Holding Side" so that your time (or distance) comes out as required on the "Non-Holding Side." There must be a good reason why these terms are used for the legs, I just never came across it. In any event, the "Sides"(legs) are labeled correctly in the diagram.
Any airspeed restrictions?
Yes. Several. Generally speaking, if you are holding from the surface up to 6,000 feet the maximum airspeed in the hold is 200knots (indicated airspeed). From 6,000 feet to 14,000 feet 230knots is the limit, and from 14,000 feet and up it is 265 knots. Note that these are maximums. And, if you're a military jock, the Navy uses 230 knots at Navy fields and the Air Force uses310 knots at the Air Force bases. In addition, some published holding patterns will have an airspeed depicted on the chart.
Keep in mind that you are holding because there is a delay in the system. There's no sense in flying around "in a circle" at maximum airspeed burning the precious fuel that you will need in your now extended flight. If you are going to be holding for an extended time notify Center that you want to slow down for fuel conservation purposes.
What about time? Do I just fly the Inbound and Outbound Legs as long as I want to?
No, there is a standard. At, or below 14,000 feet the inbound leg will be 1 minute long. Above 14,000 feet the inbound leg will be 1-1/2 minutes long.
In a perfect world there would be no wind aloft where you will be doing your hold, and the pattern that you would scribe across the surface of the Earth would look like the diagram. In this perfect world, at or below 14,000 feet, each leg would be 1 minute long. So, starting from the Fix a standard rate turn of 180 degrees would take one minute, then fly the Outbound Leg for one minute, followed by another standard rate 180 degree turn of one minute, then one minute to fly the Inbound Leg back to the Fix- 4 minutes total.
(Above 14,000 feet it would still be one minute for the 180degree turn from the Fix, one and a half minutes for the Outbound Leg, one minute for the Inbound Turn, and one and a half minutes on the Inbound Leg- 5 minutes total.)
The goal of flying a holding pattern is to make the Inbound Leg be 1 minute, or 1-1/2 minutes, in length. You can see that wind can really muck up this goal, and we will discuss that when we get to the practical flying procedures segment shortly.
Suffice to say that usually by the time you get this all figured out and the procedure nailed, Center will usually issue a "Further Clearance. "ATC "humor."
"Further Clearance"? What's that?
When you fly "in the system" certain assumptions are made. These have to do primarily with what time you are going to be at a point in space if you lost radio contact with Air Traffic Control (Center). While the regulations are specific, they do not cover all aspects of a flight. For instance, the assumption is usually made that if you have "radio failure" you will only lose your communications and not your navigation receivers. This topic could take up considerable space, and this is not the forum for it. Suffice to say that it can lead to many "what if" conversations for pilots over a Scotch and soda.
For example: If you lost your radios (the communications ones)right after departure, and continued on to your destination (not too likely) without ever talking to anyone, Center expects you to arrive over the Fix that serves the destination runway in use at the ETA that you filed in your flight plan. If you are told to hold someplace before you get to your destination airport it mucks up your ETA. Because of this Center must give you an "Expect Further Clearance" (EFC) time when they issue a hold. In addition, Center is supposed to give you an idea of how long you can expect to stay in the hold.
If you lose your radios (again, the communications ones) during the hold, you are expected to adjust your hold to arrive over the Holding Fix at the EFC time and continue your flight as you filed it in your flight plan, or as last amended by ATC. (Just for the record, Center will broadcast over navigation frequencies in an attempt to get hold of you.)
So, this is what you will receive: "Cessna 1557 Golf hold East of the Sheba VOR on the 090 degree radial as published. Expect further clearance at 20, time now 05. You can anticipate about 20 minutes in the hold." You would quickly verify that the ship's time corresponds with five minutes after the hour, then navigate as necessary to enter the hold. If you lost your communications with Center (or Approach), you would fly the last leg of the holding pattern so that you arrived over the Fix at twenty minutes past the hour- the "...expect further clearance at 20..." part of your clearance.
"Standard Rate Turn". I forget what that means.
A Standard Rate Turn is one in which the angle of bank in a turn is such that you will do a complete 360 degree circle in two minutes. So, what is that angle of bank you ask? It varies, depending on the airspeed of the aircraft that you are flying. Slower aircraft require a shallower angle of bank to do the 360,,and faster ones need a steeper angle of bank. In fact, if you think about it, it will vary within the aircraft that you are flying depending if you are going "fast" or "slow."
Well that's just fine, but how do you determine that magic angle? Ah Grasshopper, there is an instrument in your panel that tells you that. This marvelous little instrument automatically compensates for your airspeed and will always give you a Standard Rate Turn. This nifty instrument is also included on every airplane instrument panel.
And that marvelous little instrument is?
The Turn and Bank!
See that notation at the bottom? The one that reads "2min"? Bank your aircraft so that you place your wing tips on that "hash mark" above either the "L" or the "R", and you will make a Standard Rate Turn. Cool, huh? If your aircraft has the "older style" T&B indicator (the format preferred by most professional pilots incidentally),bank so that the needle is on the "dog house" and you will have a "Standard Rate Turn".
As an aside, when doing instrument flying, all maneuvers are based on the aircraft doing Standard Rate Turns during the various procedures.
Where are holding patterns (Holds)located?
Everywhere. Some are in the high-altitude sector (above 18,000feet), some are in the lower altitudes, and some are on the instrument approaches to airports. And, Center can "create" a holding pattern anywhere that it may be necessary. If Center does "create" one, they are obligated to spell out all of the criteria for you-the Fix, standard or non-standard turns, and so on.
Do holding patterns change?
They can. The pattern doesn't change, it will always be a standard rate turn of 180 degrees at each end. However, the legs may be timed or based on mileage.
The Outbound and Inbound Legs are either 1 minute or 1-1/2minutes long depending on altitude. However, if you are going to be holding for a long time, Center may issue longer legs- or you can request longer legs. Also, if the hold is associated with a navigational aid that has DME the hold may be based on distance rather than time.
Is the "Fix" always over a Nav Aid (Navigational Aid)?
No. It is usually over a Nav Aid, such as a VOR/VORTAC, the Outer Marker, a low frequency radio beacon, etc. But it may also be an intersection, or a DME (Distance Measuring Equipment) distance on a radial.
Let's look at the various types of holding patterns
DME holding, how does that work?
There's two versions, holding away from the Nav aid and holding toward the Nav aid.
DME holding away from the Nav Aid
In this type of DME hold, Center (or a notation on the chart if the hold is charted) will tell you the length of the legs. The DME readout is used for both the Inbound Turn, and the Outbound Turn. In the above example the legs are 10 miles long. The small difference caused by the angle for the DME distance on the Outbound Turn is negligible and is ignored.
DME holding toward from the Nav Aid
As in the above example, Center (or a notation on the chart if the hold is charted) will tell you the length of the legs. The DME readout is used for both the Inbound Turn, and the Outbound Turn. In the above example the legs are 10 miles long. The small difference caused by the angle for the DME distance on the Outbound Turn is negligible and is ignored.
How do you enter the holding pattern?
Before radar everyone just kind of did their own thing. When controllers got their eye in the sky they were amazed at the creativity of pilots when entering the holding patterns. Naturally, being a government operation, they adopted and published standard procedures to enter a holding pattern.
Here's the various entry procedures for a Standard Pattern(right-hand turns) hold.
Parallel entry Cross the Fix from this zone, then fly parallel to the Non-Holding side of the hold, using the reciprocal of the Holding Course. Fly this way for one minute, then do a standard rate turn "through more than 180 degrees" and return to the Fix, or intercept the Holding Course and track it inbound to the Fix.
Teardrop entry Cross the Fix from this zone, then turn 30 degrees left of the Holding Course. If, in our entry diagram, the Holding Course is the 090 degree bearing from the Fix, then a heading "30 degrees left" of that would be 060 degrees. You would turn to a heading of 060 degrees after you cross the Fix. Fly this heading for one minute, then turn in the direction of the Inbound Holding Course. Intercept the course and track it to the Fix.
Direct entry The easiest, and most common, entry. Fly direct to the Fix.
Do I have to fly the entries as shown?
No, these are the recommended entry procedures by the FAA (Federal Aviation Administration). Every hold has obstruction clearances built-in if you fly these entry procedures. If you wanted to make a direct entry from the parallel entry "zone" by making a hard 180 degree turn to join the Fix End turn, you certainly could- and you wouldn't exceed the protected airspace if you did. However, this could be disorienting to you, and certainly exciting for your passengers. And, most importantly, the FAA is watching you via their glowing screen. If a controller was having a really bad hair day he could file a violation on you.
The FAA takes the word "recommended" very seriously.
Actually the procedure starts even before you make your entry. You are expected to slow down as necessary to not exceed the published, or stated, holding airspeed when you are three minutes from the Fix. You are expected to cross the Fix at the appropriate airspeed.
OK, that's the terminology, how do you fly the hold once you have done the entry procedure and crossed the Fix?
Let's take a look at a standard holding pattern again.
Here's the "Reader's Digest" rules of holding:
- All turns must be Standard Rate turns.
- Timing for the Outbound Leg starts either over the Fix, or abeam of the Fix- whichever occurs later.
- All adjustments to the hold must be made on the Outbound Leg.
- The Inbound Leg is the leg that must be either one minute long, or one and a half minutes long, or the DME distance that is specified by ATC, or as published on a chart.
No wiggle room here is there? The only part of the hold that you can compensate for time or wind is the Outbound Leg.
Flying a holding pattern, no wind.
Prior to crossing the VOR (Fix) inbound, set your VOR display to 270 degrees (set the CDI to 270). Crossing the VOR (Fix) notify ATC that you are "...entering the hold." Establish a standard rate turn to the right. Set your VOR display to 000 degrees (set the CDI to 000). When the VOR display (or the CDI) centers you are abeam of the VOR (Fix). Start your time. Fly a heading of 090 degrees for one minute. While you are doing this reset the VOR display to 270 degrees (set the CDI to 270).After one minute of flying the 090 degree heading make a standard rate turn to the right and roll out on a 270 degree heading. The VOR display should center showing that you are on the 090 degree radial. In one minute you should cross the VOR (Fix). Make a standard rate turn to the right and start all over again. You can see that a number two navigation display or an RMI can be of great aid here.
OK, that's a hold in a perfect world. Not going to happen. Let's see what happens when that old devil wind kicks in.
Flying a holding pattern, with wind.
As you cross the VOR the wind starts pushing you to the East. You most likely will pass abeam of the VOR before you complete the turn. Flying for one minute on the Outbound Leg takes you farther away from the VOR because of the tailwind. The Outbound Turn is still in progress as you intercept the 090 Inbound radial and you fly through the radial. Compensating, you reintercept the 090 degree radial and fly it inbound. The Inbound Leg is longer than one minute because you were farther away from the VOR when you turned inbound due to the tailwind, and the inbound time is increased even more because of the headwind.
But, Center pretty much expects the first leg of the hold to be botched anyway, and the airspace protecting the hold takes this into account. How big is the "protected airspace"? You don't know, and they probably won't tell you. It's not charted. Unless you really blow it, you'll be protected.
OK, what can be done about this situation?
Well, it would be nice to make the turn at the Fix end a little shallower, and steep en up the turn at the other end but that's not allowed. (Folks do it all of the time incidentally, but we're trying to this by the book.) However, we can play with the Outbound Leg. Let's say that after you complete the Fix End turn that you fly a heading of 080 degrees rather than 090. And, let's say that you fly the Outbound Leg for 45 seconds rather than the full minute.
Remember, the Outbound Leg is yours to diddle with.
Now we get this:
Ah, that's better. Either remember "080 degrees and 45seconds" for the Outbound Leg, or write it down. Let's say that after your turn at the Outbound end you still have not intercepted the 090 inbound. Turn left so that you do, and make a note that080 was too much compensation. Next time try 085 for the outbound heading. Also, let's say that it takes one minute and fifteen seconds to make the Inbound leg. On your next circuit shorten the 45 seconds outbound to 40 and see what happens. Keep tweaking time and heading until you find the combination that works.
And, just when you finally nail it and are so proud of yourself, Center will call with another clearance- ATC humor.
I won't bore you with diagrams of each wind possibility, you can get the drift (very poor pun) from the above discussion. Just remember that you play with the Outbound Leg in both time and heading. Use your knowledge of the winds aloft and make an educated guess for your first circuit and then just keep adjusting and tweaking as necessary.
Flying a good holding pattern, i.e. nailing the Inbound Leg, is an art form and a matter of pride to a professional pilot.
I hope that this tutorial has taken away any clouds of doubt that you may have had about holding procedures. If you spot any errors, please let me know and I'll make the necessary corrections.
This tutorial was written after a suggestion by Skip Cole. Thank you Skip.
© Hal Stoen, September 2002