Turn rates in the hold
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Turn rates in the hold
Greetings, esteemed nipple-bat wearing bretheren. 
I work for a UK national ATC provider, developing the simulators we use to train baby ATCOs to give you guys the faultless, under-priced service you all have come to love so much. A small question has arisen concerning turn-rates in the hold [terminal & en-route].
Do you all still use rate one turns during entry and holding, or are the modern FMS systems bank-angle limiting you all?
Our new simulator has all the big [and big-ish] jets limiting their bank angles, even in the terminal holds, and thus we are seeing some very large turns compared to what we were previously observing on our old system. I don't want to smack the software pukes up beside the head if they are in fact replicating reality, but if reality is radically different from the performance that was used to set all the procedures up, there may be Flight Safety issue involved as well. Tried asking the Radar Watchers, they all gave different answers. As many different a/c types as possible in the answers if you'd all be so kind.
I work for a UK national ATC provider, developing the simulators we use to train baby ATCOs to give you guys the faultless, under-priced service you all have come to love so much. A small question has arisen concerning turn-rates in the hold [terminal & en-route]. Do you all still use rate one turns during entry and holding, or are the modern FMS systems bank-angle limiting you all?
Our new simulator has all the big [and big-ish] jets limiting their bank angles, even in the terminal holds, and thus we are seeing some very large turns compared to what we were previously observing on our old system. I don't want to smack the software pukes up beside the head if they are in fact replicating reality, but if reality is radically different from the performance that was used to set all the procedures up, there may be Flight Safety issue involved as well. Tried asking the Radar Watchers, they all gave different answers. As many different a/c types as possible in the answers if you'd all be so kind.
From the perspective of designing a holding procedure (yes, there is such a process!) all turns are made at a bank angle of 25 degrees or at a rate of 3 degrees per second, which ever requires the lesser bank.
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Personally use 25 degree angle of bank for all holding, notwithstanding what the FMS says...at this end the PILOT flies the aeroplane, not the FMS. Suspect some of the "newer" guys don't know the difference.
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Despite Autoland/FMS capability I always handfly below 10,000 AGL just for the challenge, and to stay sharp. Some of my copilots stay coupled not only in a hold, but until LOC and G/S intercept ...probably because the airplane still is way over their heads. I decline to be an instructor and I do not impose my technique unto any F/O.
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Around LHR, we use the FMGC. The Airbus one seems to do tighter turns than the B737 one - but both work on racetracks. Which can be big in strong crosswinds.
I almost never handfly in a busy TMA (where holding is likely), because I would like as much capacity as possible from both pilots to be available for situational awareness. Or even more. Too many incidents happen in TMA's as it is.
I almost never handfly in a busy TMA (where holding is likely), because I would like as much capacity as possible from both pilots to be available for situational awareness. Or even more. Too many incidents happen in TMA's as it is.
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DWB,
What company do you work for?
Simulating ATC sounds a damn sight more interesting than modelling financial transactions for a bunch of overpaid barrow-boy traders.
What kinds of technologies do you deal with??
Does your outfit have a web site??
???pax
What company do you work for?
Simulating ATC sounds a damn sight more interesting than modelling financial transactions for a bunch of overpaid barrow-boy traders.
What kinds of technologies do you deal with??
Does your outfit have a web site??
???pax
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Thankyou all for your prompt responses. I guess the software bods will escape the slapping this time. The kit is bank limiting at around 25º which is giving a rate of 1.78 º/sec at FL140. This is going to cause a ruction or two amongst some of the more Luddite of teh ATC bretheren around here, but I think it about time they were dragged into the 21st century [or the 20th at least]
???pax
NATS mate. www.nats.co.uk. Check out the ATC forum on this here site, and see how much we all like working here.
Technology wise, from state of the art, to state of the ark. The simulators all run on SOLARIS boxes and PCs. We just gutted most of our R&D capacity, so I don't know what the hiring situation is at the moment, but it sounds like it can't be any worse than what you currently do.
???pax
NATS mate. www.nats.co.uk. Check out the ATC forum on this here site, and see how much we all like working here.
Technology wise, from state of the art, to state of the ark. The simulators all run on SOLARIS boxes and PCs. We just gutted most of our R&D capacity, so I don't know what the hiring situation is at the moment, but it sounds like it can't be any worse than what you currently do.
Last edited by Dances with Boffins; 15th Aug 2002 at 13:29.
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DWB, I suspect I may be one of your Luddite bretheren.
I don'y know the answer to your question but it occurs to me that if modern aircraft don't fly in accordance with the Standards set by ICAO then the dimensions of the holding area and separation between holds may not provide the space between aircraft that everyone thinks there is.
Think about that next time you're cleared into a hold under a procedural service. And yes, aircraft still get procedurally controlled sometimes.
I don'y know the answer to your question but it occurs to me that if modern aircraft don't fly in accordance with the Standards set by ICAO then the dimensions of the holding area and separation between holds may not provide the space between aircraft that everyone thinks there is.
Think about that next time you're cleared into a hold under a procedural service. And yes, aircraft still get procedurally controlled sometimes.
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We don't have rate of turn indicators on most jet airplanes, and we use 25 deg of bank for turning, which at the normal hold speeds gives around half rate turns. (1.5 deg per second)
Spitoon,
If you have look at the holding pattern design criteria, you may very well be surprised.
The holding patter protected areas don’t look anything like a holding patter shown as a racetrack, but does take into account quite extreme possible winds.
On an ATC radar, it is not to hard to work out who is using the FMCS system of current aircraft to track the racetrack, their ground track actually looks something (very) like the neat little diagram on the chart. The rest are all over the shop.
Many pilots have been using all sorts of wind compensation for years, but this is largely disregarded in working out the protected areas. For my money, keep using them, you will stay closer to the racetrack, but you don't have to.
The bottom line is ----- all FMS aircraft will say well within the protected areas, some airecraft will exceed 30 degrees of bank on autopilot to maintain the FMS track. Users of the antiquated braincrank systems, short of really gross miscalculation and equally gross flying, will be quite safe.
Seems to me that whoever established the original design criteria had a remarkably practical approach to the real world.
Tootle pip !!!
If you have look at the holding pattern design criteria, you may very well be surprised.
The holding patter protected areas don’t look anything like a holding patter shown as a racetrack, but does take into account quite extreme possible winds.
On an ATC radar, it is not to hard to work out who is using the FMCS system of current aircraft to track the racetrack, their ground track actually looks something (very) like the neat little diagram on the chart. The rest are all over the shop.
Many pilots have been using all sorts of wind compensation for years, but this is largely disregarded in working out the protected areas. For my money, keep using them, you will stay closer to the racetrack, but you don't have to.
The bottom line is ----- all FMS aircraft will say well within the protected areas, some airecraft will exceed 30 degrees of bank on autopilot to maintain the FMS track. Users of the antiquated braincrank systems, short of really gross miscalculation and equally gross flying, will be quite safe.
Seems to me that whoever established the original design criteria had a remarkably practical approach to the real world.
Tootle pip !!!
If you watch the bank angle in the hold you will see the FMC changing the bank angle depending on the x-wind to fly the racetrack pattern rather than using a drift correction on the outbound leg. Very clever and works really well, if you want to get all hair shirt about it and fly it on the needles or by hand then go ahead, I just like to keep it simple. It is all very well for Glueball to say that he does not impose his technique on FO's but he clearly does just by doing it. Saying you always hand fly below 10000ft is a real no brainer, there are clearly times when it is appropriate to do so but also times when it isn't. Poor weather, lots of traffic, busy holding stack, busy radio and two tired pilots are not the time to show how much "right stuff" you have.
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Lead, I know what the holding areas look like (and how big they get at upper levels! 
) - but the PANS criteria assume that pilots fly their aircraft like Annex 6 (or wherever it's laid down) says.
All I was saying was that if FMCs or pilots don't fly within the parameters that are assumed when holding areas and other separation criteria are calculated then aircraft will get closer than they're supposed to.
) - but the PANS criteria assume that pilots fly their aircraft like Annex 6 (or wherever it's laid down) says. All I was saying was that if FMCs or pilots don't fly within the parameters that are assumed when holding areas and other separation criteria are calculated then aircraft will get closer than they're supposed to.
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If your sim software can work out TAS how about the TAS divided by 10 +7 degrees to calculate the rate 1 bank angle.
Turns in the hold should always be rate 1.
Turns in the hold should always be rate 1.
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DWB.
I'm only a Boeing driver and choose to fly the holds in LNAV. 3 times the drift outbound etc is for a/c that cost less than the autopilot of a decent Boeing. LNAV will use upto 30 degrees of bank to hold the track. We are told that it will calculate a race track that will stay within the protected area and use a 'maximum' of 30 degrees. On calm days or a slight head wind in the turns bank angles as low as 15 are sometimes used. The FMC hold speeds are generally slower than the ICAO max'. I suppose I have to trust the statement that LNAV will keep me within the protected area. I've no way of knowing differently.
I've not expereinced trying to hold in sensitive areas with gale force cross winds. As LNAV is limited to 30 degrees I guess it'll infringe the boundaries. If so it's time to be on the ground sharpish.
I'm only a Boeing driver and choose to fly the holds in LNAV. 3 times the drift outbound etc is for a/c that cost less than the autopilot of a decent Boeing. LNAV will use upto 30 degrees of bank to hold the track. We are told that it will calculate a race track that will stay within the protected area and use a 'maximum' of 30 degrees. On calm days or a slight head wind in the turns bank angles as low as 15 are sometimes used. The FMC hold speeds are generally slower than the ICAO max'. I suppose I have to trust the statement that LNAV will keep me within the protected area. I've no way of knowing differently.
I've not expereinced trying to hold in sensitive areas with gale force cross winds. As LNAV is limited to 30 degrees I guess it'll infringe the boundaries. If so it's time to be on the ground sharpish.
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In addition to rate one turns giving 25 degress of bank in a hold the 737 when in Lnav to maintain the lateral track in a hold can and will bank upto 30degrees...........I didnt read this in a book but but see it on the line day in day out.
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Bearcat.
You're correct, you have seen it because it is an OK thing. HDG SEL has a limit of 25' if so selected, or at slow speed in auto. However, LNAV has a limit of 30' and will use it do get the task done if necessary. This could be at any time, such as route capturing or route modification at altitude.
What I do not remember seeing is a hold turn taking 60secs to complete. It is always about 80-90 secs. The rate one theory is therefore not applied.
You're correct, you have seen it because it is an OK thing. HDG SEL has a limit of 25' if so selected, or at slow speed in auto. However, LNAV has a limit of 30' and will use it do get the task done if necessary. This could be at any time, such as route capturing or route modification at altitude.
What I do not remember seeing is a hold turn taking 60secs to complete. It is always about 80-90 secs. The rate one theory is therefore not applied.
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Getting back to the point all turns should be rate one, If not let Jeppesen and Aerad know so they can re survey all the airports.
As near as damm it, 25-30deg at a holdimg speed of 200- 230kts will be pretty close to a rate one turn
As near as damm it, 25-30deg at a holdimg speed of 200- 230kts will be pretty close to a rate one turn
