IVAO i-Pack

L6 - Holdings

25-11-2005

Additional references: L-5 Charts L-6 EAT

1. Holdings

The main purpose of a holding is to regulate traffic flow in congested areas. In reality ATC will avoided holdings and only issues a holding instruction if its use is inevitable. To regulate large traffic flow ATC more often issues "direct to..." instructions or uses delaying radar vectors.
In this section of the i-PACK we use the following holding as an example:

The picture above displays the published approach for runway 06 at Schiphol Amsterdam. You can clearly see the holding depicted with SPL (Schiphol VOR) as the holding fix.

2. Standard/Non-Standard Holdings

A holding pattern has the form of a racetrack and consists of the following elements:

• Holding fix [can be a VOR/NDB/DME (navaid) or fix (intersection)].

• Outbound turn [standard rate turn (3° per second)].

• Outbound leg [leg in the opposite direction of the inbound leg, not timed]

• Inbound turn [standard rate turn back to inbound leg]

• Inbound leg [this is the leg ATC refers to, this leg must be flown for 1 minute at or below 14000ft and for 1,5 minute above 14000ft if not otherwise instructed].

A holding with turns to the right is called a standard holding, one with turns to the left is called a non-standard holding. Sometimes ATC may instruct you to fly a "standard holding" instead of "right turns". Note that ATC can also give DME holding instructions, 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 is needed, since the DME distances given by ATC describe the end of the inbound leg and the start of the turn outbound etc.

Note: Usually specific holding restrictions such as minimum flight level or maximum speed are published on charts. These restrictions should be observed.

3. Holding clearance

A typical holding instruction has this form:

• Aircraft identification; call sign

• 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) or in case of a holding over the IAF; Estimated approach time (EAT)

• Current time (optional)

Example: KLM642, hold over SPL, inbound heading 228, right turns, descent and maintain FL70, expect further clearance in 15 minutes.

"KLM642"; the aircrafts call sign

"hold over SPL"; the holding fix

"inbound heading 228"; this means that the inbound leg should be flown on heading 228

"right turns"; indicates that all turns are turns to the right (standard holding)

"descent and maintain FL070"; the pilot is instructed to descent while in the holding to FL070 and after reaching the assigned FL he should maintain this level

"expect further clearance in 15 minutes"; the pilot may expect to leave the holding in 15 minutes

ATC may also add the following line; xx minute leg approved.
You can imagine that if you have to fly several holdings with a 1 minute inbound leg this will displease the passengers, so for passenger comfort sometimes xx minute legs are approved.
ATC sometimes abbreviates the holding instructions if the holding is published on charts, e.g. approach plates. In this case ATC may instruct you to hold "as published" or "join the published holding over XXX". Or simply "join the holding over XXX". This is only done if it's obvious which holding is mentioned. For SPL there are several holdings published, each one for a different approach and runway. In such a case ATC has to clearly instruct which published holding should be flown.

Example: KLM642, cleared for the published approach runway 06, join the published holding over SPL, FL70, expected approach time in 10 minutes. 2 minute legs are approved.

The KLM642 is now instructed to fly the approach of runway 06 as indicated in Figure 1. Depending from which IAF (ARTIP, RIVER of SUGOL) the aircraft is coming the appropriate approach should be flown and at SPL the published holding for that approach should be executed.

Note: Please be aware that a holding doesn't need to be directly issued by ATC. In some cases a holding must be flown without specific instructions by ATC, e.g.

• if the last waypoint point you have been cleared to, the Clearance Limit, is reached without further ATC instructions, or

•  when communications have been lost. In that case use a standard holding pattern (right turns) upon reaching the Clearance Limit.

4. Flying the instructed holding

We received the instruction to fly the holding as seen in Figure 1. We have copied the instruction and given our read-back, and ATC expects us to fly the holding as instructed.
The first thing to do is to check the remaining fuel and if you can make it to in the EFC/EAT. When given an EAT, the pilot is responsible for managing the airspeed and holding pattern so that s/he passes the IAF at the given time, even if this means that the published legs of the pattern have to be shortened (e.g., to 30 seconds instead of the published 1 minute).
After calculation time and leg length you reduce the airspeed (advise or ask ATC). Holdings are there for waiting purposes so there is no need to rush. Perhaps, if you reduce your airspeed early enough you may even avoid the holding. Moreover, the extra time gained during slow flight will help you figure out your position in reference to the holding fix and which holding entry you would have to fly. Many times a holding speed limitation is published on the holding chart. If not, one should comply with the limitations as published in the countries AIP.

Holding entries

Now that we are heading towards the holding fix or position we should establish which holding entry to fly.

There are three types of holding entries:

Figure 2: Holding Entry areas.

If an aircraft is approaching from the red shaded part, the aircraft has to fly a "Direct Entry". If a pilot is approaching from the blue shaded part, a "Parallel Entry" should be flown. Approaching from the green shaded part indicates that an "Offset Entry" (Teardrop Entry in the USA) should be flown. The corresponding entry procedures are shown in figure 3 below:

Direct Entry

If approaching from the red shaded part, fly a direct entry as shown in the picture to the left. The picture to the right displays the same holding with left turns (Non-Standard Holding).

Parallel Entry

If approaching from the blue shaded part, fly a parallel entry as shown in the picture to the left. Again, the picture to the right displays the same holding with left turns (Non-Standard Holding).
You can clearly see that if we would approach from the same heading as in the picture on the left but now for a non-standard holding, we'd have to fly a different entry (see the description for the Offset Entry).

Offset Entry

also called

Tear drop Entry

If approaching from the green shaded part, fly an offset entry as displayed in the picture on the left. Again the picture on the right displays the same holding with left turns (Non-standard Holding). You can clearly see that if we would approach from the same direction as in the picture on the left we'd have to fly a different entry (see the description for parallel entry).

For the inbound leg:

• Start: As soon as you roll out from the inbound turn or when intercepting the inbound track
• Stop: When directing to the station at a VOR (the flag changes from TO to FROM) or a NDB (the pointer changed direction rapidly).

For the outbound leg:

• Start :If the Holding fix is a VOR, when the TO-FROM indicator changes from FROM to TO
• Start: If the holding fix is a NDB, when the needle points (with no wind) 90 degrees to the left (non-standard) or the right (standard)

You end the outbound time and start the inbound turn depending on the wind as discussed further in this section.

If you don't know the winds aloft data, fly the first pattern with a one minute outbound leg. Then measure the time required to fly the inbound leg. Now check whether the inbound leg was flown less or more than one minute. Now for the second pattern, add or subtract difference between one minute and the time you have flown the inbound leg to one minute.

Exiting the holding

We have entered the holding and have flown a couple of patterns. Our EFC or EAT is near, ask the ATC for clearance to leave the holding. ATC may clear you to either leave the holding or for another round in the holding if needed. In case of a communication failure set your squawk to 7600 and hold until reaching the EFC or EAT. Then leave the holding and continue your flight.
A typical example of a clearance to leave the holding is:

Example: KLM642, when overhead SPL, leave the holding on heading 250 to start your approach for runway 06.

	"KLM642"; the aircrafts call sign
	"when overhead SPL"; the holding fix
	"leave the holding on heading 250"; this means that after reaching SPL you turn to a heading of 250 degrees to leave the holding
	"to start your approach for runway 06"; when you have left the holding, you will finally start your approach

Paul de Jong NL-TAC

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