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'''Holding management''' is an essential part of providing professional ATC - not only but especially in high traffic situations. This tutorial shows what to keep in mind regarding holdings and includes basics of holdings and advanced holding management.  
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Holding management is an essential part of providing professional ATC - not only but especially in high traffic situations. This tutorial shows what to keep in mind regarding holdings and includes basics of holdings and advanced holding management.  
 
  
  
 +
== Definition  ==
  
 
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A holding (or holding pattern or hold) is a maneuver designated to delay airplanes in flight by keeping them within a specified airspace. Standard holding patterns use right turns, non-standard ones use left turns. Holding patterns may be published on charts (enroute, STARs, approach) or may be given by ATC. Holdings may be anchored on a VOR, VOR/DME, NDB or compass locator, intersection or DME distances.
Contents [hide]
 
1 Definition
 
2 Standard Holding Pattern
 
3 ATC Holding Clearances
 
4 Altitudes And Speed Restrictions
 
5 Holding Stack And Separation
 
6 References
 
 
   
 
   
  
Definition A holding (or holding pattern or hold) is a maneuver designated to delay airplanes in flight by keeping them within a specified airspace. Standard holding patterns use right turns, non-standard ones use left turns. Holding patterns may be published on charts (enroute, STARs, approach) or may be given by ATC. Holdings may be anchored on a VOR, VOR/DME, NDB or compass locator, intersection or DME distances.
+
== Standard Holding Pattern  ==
  
 +
A standard holding pattern consists of:
  
 +
*The holding fix
 +
*A right 180° turn at standard rate (3 degrees/sec) away from the holding fix
 +
*An outbound leg (standard length: 1 minute below 14000 ft, see below for speed/altitudes)
 +
*A right 180° turn at standard rate towards the holding fix
 +
*An inbound leg (standard length: 1 minute)
  
 
Standard Holding Pattern A standard holding pattern consists of:
 
 
The holding fix
 
A right 180° turn at standard rate (3 degrees/sec) away from the holding fix
 
An outbound leg (standard length: 1 minute below 14000 ft, see below for speed/altitudes)
 
A right 180° turn at standard rate towards the holding fix
 
An inbound leg (standard length: 1 minute)
 
 
However, pilots have to correct wind shifts, and therefore there is hardly any "ideal" standard pattern.  
 
However, pilots have to correct wind shifts, and therefore there is hardly any "ideal" standard pattern.  
  
A standard holding pattern  
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[http://upload.wikimedia.org/wikipedia/commons/5/5e/HoldDirectEntry.svg A standard holding pattern]
 +
  
 +
== ATC Holding Clearances  ==
  
 +
A typical ATC holding clearance for a published holding could be: ''"AUA123, enter holding at NERDU as published, maintain FL90, (220 knots), 1 minute leg, expect further clearance at 1015Z."''
  
 +
Of course, there are times when an ATC - for any reason - can't clear a published holding. Possible holding fixes can be any waypoints, VORs or NDBs, also DME distances or the current position. Anyway, as it is a non-published holding, ATC has to give more information so that pilots know how to fly the holding - for example: ''"AUA123, proceed direct and hold at NIGSI, FL110, 2 minutes leg, left orbit, expect further clearance at 1310Z."''
  
ATC Holding Clearances A typical ATC holding clearance for a published holding could be: "AUA123, enter holding at NERDU as published, maintain FL90, (220 knots), 1 minute leg, expect further clearance at 1015Z."
+
For longer holdings keep in mind that the pilot has to crosscheck the EFC-time ('''e'''xpect '''f'''urther '''c'''learance-time) with available fuel (reserves). Note: the EFC-time is always assigned in the USA (FAA procedures), however in most parts of Europe and also in South America ATC never gives EFC-time, especially for shorter holdings (10-20 minutes). However, advising an EFC-time - if possible - is always a service for the pilot and should be done.  
 
 
Of course, there are times when an ATC - for any reason - can't clear a published holding. Possible holding fixes can be any waypoints, VORs or NDBs, also DME distances or the current position. Anyway, as it is a non-published holding, ATC has to give more information so that pilots know how to fly the holding - for example: "AUA123, proceed direct and hold at NIGSI, FL110, 2 minutes leg, left orbit, expect further clearance at 1310Z."
 
 
 
For longer holdings keep in mind that the pilot has to crosscheck the EFC-time (expect further clearance-time) with available fuel (reserves). Note: the EFC-time is always assigned in the USA (FAA procedures), however in most parts of Europe and also in South America ATC never gives EFC-time, especially for shorter holdings (10-20 minutes). However, advising an EFC-time - if possible - is always a service for the pilot and should be done.  
 
  
 
ATC has to issue further instructions while the airplane is in the hold if:  
 
ATC has to issue further instructions while the airplane is in the hold if:  
  
The delay exceeds one hour  
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*The delay exceeds one hour  
A revised EFC is necessary  
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*A revised EFC is necessary  
Weather is becoming less than the required for the intended approach  
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*Weather is becoming less than the required for the intended approach  
Other operational information is necessary (eg: airport closed)  
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*Other operational information is necessary (eg: airport closed)
 
 
 
 
  
Altitudes And Speed Restrictions ICAO holding restrictions  Altitude segment for holding  Speed (IAS/Mach) in the holding  Time length of legs 
 
surface to 14,000 ft  max. 230 kts  1 minute 
 
14,001 to 20,000 ft  max. 240 kts  1 1/2 minutes 
 
20,001 to 34,000 ft  max. 265 kts  1 1/2 minutes 
 
above 34,001 ft  max. 0,83 Mach 1 1/2 minutes 
 
  
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== Altitudes And Speed Restrictions ==
  
Every published holding has got a minimum holding altitude (MHA) which is noted on the charts. For example, NERDU has an MHA of 5,000 ft (see STAR chart for LOWW here: [1]).
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{| width="600" border="1" cellpadding="1" cellspacing="1"
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|+ ICAO holding restrictions
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|-
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! scope="col" | Altitude segment for holding  
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! scope="col" | Speed (IAS/Mach) in the holding
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! scope="col" | Time length of legs
 +
|-
 +
| surface to 14,000 ft
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| max. 230 kts
 +
| 1 minute
 +
|-
 +
| 14,001 to 20,000 ft
 +
| max. 240 kts
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| 1 <sup>1</sup>/<sub>2</sub> minutes
 +
|-
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| 20,001 to 34,000 ft  
 +
| max. 265 kts
 +
| 1 <sup>1</sup>/<sub>2</sub> minutes
 +
|-
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| above 34,001 ft
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| max. 0,83 Mach<span class="Apple-tab-span" style="white-space:pre"> </span>
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| 1 <sup>1</sup>/<sub>2</sub> minutes<sup></sup>
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|}
  
Note that, for operational requirements (e.g. if an extended period of holding is foreseen, to avoid too many “rounds” for passenger comfort or to stay in clean configuration), the pilot may request and ATC grant (if possible), either longer legs (usually 2 minutes) or higher speeds in the holding pattern.
+
<span style="line-height: normal;">
 +
</span>
  
 +
Every published holding has got a minimum holding altitude (MHA) which is noted on the charts. For example, NERDU has an MHA of 5,000 ft (see STAR chart for LOWW here: [http://charts.vacc-austria.org/LOWW/LOWW_Arrival_STAR_08042012.pdf]).
  
 +
Note that, for operational requirements (e.g. if an extended period of holding is foreseen, to avoid too many “rounds” for passenger comfort or to stay in clean configuration), the pilot may request and ATC grant (if possible), either longer legs (usually 2 minutes) or higher speeds in the holding pattern.
  
  
Holding Stack And Separation In periods of very high traffic it may be required that two or more aircraft hold above the same fix. In this case ATC must consider:
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== Holding Stack And Separation ==
  
Approach sequence shall be kept unchanged. The aircraft that enters the holding at first, should leave it at first too.  
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In periods of very high traffic it may be required that two or more aircraft hold above the same fix.
Aircraft must be separated 1000 feet vertically.  
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In this case ATC must consider:
Aircrafts may be advised to descend in the holding if necessary for succeeding approach.  
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*Approach sequence shall be kept unchanged. The aircraft that enters the holding at first, should leave it at first too.
An aircraft may be cleared to a level previously occupied by another aircraft only after the latter has reported vacating it, except when:
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*Aircraft must be separated 1000 feet vertically.
 +
*Aircrafts may be advised to descend in the holding if necessary for succeeding approach.
  
severe turbulence is known to exist;  
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An aircraft may be cleared to a level previously occupied by another aircraft only after the latter has reported vacating it, except when:
the higher aircraft is effecting a cruise climb; or  
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*severe turbulence is known to exist;
the difference in aircraft performance is such that less than the applicable separation minimum may result; in which case such clearance shall be withheld until the aircraft vacating the level has reported at or passing another level separated by the required minimum.
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*the higher aircraft is effecting a cruise climb; or
When the aircraft concerned are established in the same holding pattern, consideration shall be given to aircraft descending at markedly different rates and, if necessary, additional measures such as specifying a maximum descent rate for the higher aircraft and a minimum descent rate for the lower aircraft, should be applied to ensure that the required separation is maintained.  
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*the difference in aircraft performance is such that less than the applicable separation minimum may result; in which case such clearance shall be withheld until the aircraft vacating the level has reported at or passing another level separated by the required minimum.
  
Radar separation shall not be applied between aircraft holding over the same holding point!
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When the aircraft concerned are established in the same holding pattern, consideration shall be given to aircraft descending at markedly different rates and, if necessary, additional measures such as specifying a maximum descent rate for the higher aircraft and a minimum descent rate for the lower aircraft, should be applied to ensure that the required separation is maintained.
  
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Radar separation shall not be applied between aircraft holding over the same holding point!
  
  
  
References United Virtual Airlines Trainings Departement: Pilot's Guide. Holdings (http://www.united-virtual.com/files/documents/UVA_Guides_HOLDING.pdf)
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== References ==
  
IVAO: Minimum Radar Vectoring Altitude (MRVA) (http://academy.ivao.aero/node/418)  
+
United Virtual Airlines Trainings Departement: Pilot's Guide. Holdings (http://www.united-virtual.com/files/documents/UVA_Guides_HOLDING.pdf)
  
Retrieved from "http://wikitest.vacc-austria.org/index.php?title=Holding_management"Personal tools
+
IVAO: Minimum Radar Vectoring Altitude (MRVA) (http://academy.ivao.aero/node/418)
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Revision as of 16:14, 21 April 2012

Holding management is an essential part of providing professional ATC - not only but especially in high traffic situations. This tutorial shows what to keep in mind regarding holdings and includes basics of holdings and advanced holding management.


Definition

A holding (or holding pattern or hold) is a maneuver designated to delay airplanes in flight by keeping them within a specified airspace. Standard holding patterns use right turns, non-standard ones use left turns. Holding patterns may be published on charts (enroute, STARs, approach) or may be given by ATC. Holdings may be anchored on a VOR, VOR/DME, NDB or compass locator, intersection or DME distances.


Standard Holding Pattern

A standard holding pattern consists of:

  • The holding fix
  • A right 180° turn at standard rate (3 degrees/sec) away from the holding fix
  • An outbound leg (standard length: 1 minute below 14000 ft, see below for speed/altitudes)
  • A right 180° turn at standard rate towards the holding fix
  • An inbound leg (standard length: 1 minute)

However, pilots have to correct wind shifts, and therefore there is hardly any "ideal" standard pattern.

A standard holding pattern


ATC Holding Clearances

A typical ATC holding clearance for a published holding could be: "AUA123, enter holding at NERDU as published, maintain FL90, (220 knots), 1 minute leg, expect further clearance at 1015Z."

Of course, there are times when an ATC - for any reason - can't clear a published holding. Possible holding fixes can be any waypoints, VORs or NDBs, also DME distances or the current position. Anyway, as it is a non-published holding, ATC has to give more information so that pilots know how to fly the holding - for example: "AUA123, proceed direct and hold at NIGSI, FL110, 2 minutes leg, left orbit, expect further clearance at 1310Z."

For longer holdings keep in mind that the pilot has to crosscheck the EFC-time (expect further clearance-time) with available fuel (reserves). Note: the EFC-time is always assigned in the USA (FAA procedures), however in most parts of Europe and also in South America ATC never gives EFC-time, especially for shorter holdings (10-20 minutes). However, advising an EFC-time - if possible - is always a service for the pilot and should be done.

ATC has to issue further instructions while the airplane is in the hold if:

  • The delay exceeds one hour
  • A revised EFC is necessary
  • Weather is becoming less than the required for the intended approach
  • Other operational information is necessary (eg: airport closed)


Altitudes And Speed Restrictions

ICAO holding restrictions
Altitude segment for holding Speed (IAS/Mach) in the holding Time length of legs
surface to 14,000 ft max. 230 kts 1 minute
14,001 to 20,000 ft max. 240 kts 1 1/2 minutes
20,001 to 34,000 ft max. 265 kts 1 1/2 minutes
above 34,001 ft max. 0,83 Mach 1 1/2 minutes

Every published holding has got a minimum holding altitude (MHA) which is noted on the charts. For example, NERDU has an MHA of 5,000 ft (see STAR chart for LOWW here: [1]).

Note that, for operational requirements (e.g. if an extended period of holding is foreseen, to avoid too many “rounds” for passenger comfort or to stay in clean configuration), the pilot may request and ATC grant (if possible), either longer legs (usually 2 minutes) or higher speeds in the holding pattern.


Holding Stack And Separation

In periods of very high traffic it may be required that two or more aircraft hold above the same fix. In this case ATC must consider:

  • Approach sequence shall be kept unchanged. The aircraft that enters the holding at first, should leave it at first too.
  • Aircraft must be separated 1000 feet vertically.
  • Aircrafts may be advised to descend in the holding if necessary for succeeding approach.

An aircraft may be cleared to a level previously occupied by another aircraft only after the latter has reported vacating it, except when:

  • severe turbulence is known to exist;
  • the higher aircraft is effecting a cruise climb; or
  • the difference in aircraft performance is such that less than the applicable separation minimum may result; in which case such clearance shall be withheld until the aircraft vacating the level has reported at or passing another level separated by the required minimum.

When the aircraft concerned are established in the same holding pattern, consideration shall be given to aircraft descending at markedly different rates and, if necessary, additional measures such as specifying a maximum descent rate for the higher aircraft and a minimum descent rate for the lower aircraft, should be applied to ensure that the required separation is maintained.

Radar separation shall not be applied between aircraft holding over the same holding point!


References

United Virtual Airlines Trainings Departement: Pilot's Guide. Holdings (http://www.united-virtual.com/files/documents/UVA_Guides_HOLDING.pdf)

IVAO: Minimum Radar Vectoring Altitude (MRVA) (http://academy.ivao.aero/node/418)