Rhinozherous

Probability for Holding

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Hey Pilots!

I want to set the probability for holdings in the settings of PRO-ATC X to a somewhat real value... What would you say is a good value (0-100%) for the probability of holdings? I think about an overall value for the "whole world".

Thanks!

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In the US there are very few holds these days - they would use vectoring instead. 

But I wouldn't use higher number than .. say 2%. But of course this is just an "average" over the whole world - when flying into Heathrow airport arrival holds may be routine during some periods of the day. This is the problem with "average".

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Probability based on what. Every hour? Every two hours? Every 24 hours? In the many flights I've flown, I've only ever experienced a hold twice. I'll use Newark as an example since I've flown there more often, but the last flight I flew into Newark, we were put in a hold around Allentown, and we only did one lap before we were cleared in. That was the only time I've been in a hold going into Newark, and I've flown into there 12 times (I'm not counting departures, only arrivals since you wouldn't be in a hold in the air on a departure obviously).

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There's no worldwide average for holdings i'm afraid. In RL there are only a few scenarios where you would be put into a holding:

1: To allow ATC to deal with traffic congestion and/or bad weather situations (fog)

2. In case of a temporary runway closure, i.e. to perform a runway check

3. Some STARs feature a required hold, usually at single runway airports where back tracking is required. (RTT at LOW for example) This is to ensure that no airplane enters the approach vector without ATC instructing them to do so. However, in case of good weather and low traffic, ATC would almost certainly allow to skip the hold 

 

In regards to setting the hold probability in PATCX, i would set it individually for every flight, based on the following factors: Airport size. weather and time of arrival. So if you are bound to land at Gatwick during rush hour with low visibility conditions.....you can set the probability pretty high ;)

 

EDIT: You may also want to check if your destination airport has any holdings set in PATCX, i'm not sure if PATCX will create its own holding if there's no holding in the DB. 

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4 hours ago, Rhinozherous said:

What would you say is a good value (0-100%) for the probability of holdings? I think about an overall value for the "whole world".

Thanks!

Well I can tell you exactly! I've done 1466 sectors (737-800) in the last 6 years and I've held 21 times! (The joys of a electronic logbook!) so 1.5% of all sectors I've flown. (Short-Medium Haul at airports of various sizes).

In Europe It's not terribly common but it really depends what the weather is like, where you're going and and what time you go! Even at major international airports you can at certain times get straight in or perhaps ATC will sequence aircraft with delaying vectors. They'll start holding when they can't get everyone in sequentially or there are too many aircraft for the radar controller to manage.

 

 

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49 minutes ago, flightdeck2sim said:

 

Well I can tell you exactly! I've done 1466 sectors (737-800) in the last 6 years and I've held 21 times! (The joys of a electronic logbook!) so 1.5% of all sectors I've flown. (Short-Medium Haul at airports of various sizes).

In Europe It's not terribly common but it really depends what the weather is like, where you're going and and what time you go! Even at major international airports you can at certain times get straight in or perhaps ATC will sequence aircraft with delaying vectors. They'll start holding when they can't get everyone in sequentially or there are too many aircraft for the radar controller to manage.

 

 

This is really an exact answer! :-D I thought it is way more common. 

Thank you very much!

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I've held twice in the last year, once going into Atlanta and once trying to get to lga which ended up in a divert (Don't ask, what a mess!). 600 hours of flights I guess? 

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I've only been in a hold twice in 30 years of airline flying. Once on my way to KATL which was a hold for weather to clear and lasted for about 10 minutes.

The other hold was an American Airlines flight from Rio de Janeiro to São Paulo for a connection to Dallas. We were in a 767 with the seat back screens were you could watch the flight GPS progress. I think the hold was around 45 minutes as they had some nasty WX in São Paulo that they wanted to clear before landing. The ride is was still pretty rough and I thought for sure we'd be going around but they managed on the first approach to land. When we were deboarding I heard the Capt tell the FO that he was glad he'd take on 30 minutes extra fuel. 

Come to think of it in all my years I've only been on one go-around as well going into a stormy KCLT. 

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I'm 47 and fly every week for work. I've only been placed in a holding pattern twice. Both due to weather. The second time came just a couple months ago when KTPA was having storms right over the airport.

You will find most holding situations due to weather than congestion. I would say set the percentage depending on the weather and where you are flying too. Florida on Summer afternoons, raise. Florida in the winter, lower

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ATC likes to use speed control as well.  With VATSIM one of the guys for NY ARTCC got ahold of some NY information and found they have gates so controller can have like X number of aircraft passing each gate per minute to satisfy the one (maybe two) runways at NEwark landing, which can accomodate 60 aircraft max per hour.  If they have two runways, it might be near 80, but they are really pushing it.  Of course that's under VFR conditions and light winds.

So, if a controller starts getting too many aircraft he can start slowing planes down and if needed to call up his neighbors and tell them to slow as well (and even those lovely ground stops you hear about).  I believe this is called metering.  Then there is rarely a need for holds.  I remember flying into EWR from the SW a couple of times and the pilot saying that we were being slowed over DC.  I think mach speed slowed .74 at that point.

 

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1 hour ago, bic said:

ATC likes to use speed control as well.  With VATSIM one of the guys for NY ARTCC got ahold of some NY information and found they have gates so controller can have like X number of aircraft passing each gate per minute to satisfy the one (maybe two) runways at NEwark landing, which can accomodate 60 aircraft max per hour.  If they have two runways, it might be near 80, but they are really pushing it.  Of course that's under VFR conditions and light winds.

So, if a controller starts getting too many aircraft he can start slowing planes down and if needed to call up his neighbors and tell them to slow as well (and even those lovely ground stops you hear about).  I believe this is called metering.  Then there is rarely a need for holds.  I remember flying into EWR from the SW a couple of times and the pilot saying that we were being slowed over DC.  I think mach speed slowed .74 at that point.

 

So, the Supervisor may say to the controller working a certain sector "make aircraft separation 15 miles in trail at Broadway (intersection)".  When it was 5 miles in trail at Broadway previously.  Most likely this means that the runway or other sectors are getting very busy and they need to slow your sector arrivals up.  Maybe even the weather such as thunderstorm is occurring.

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