Minimum jet separation on final
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Minimum jet separation on final
In the absense of departures and cross runway operation, what is the minimum distance or time between arriving medium jets? Is 4 nm enough? Should following aircraft make small speed adjustments based on TCAS to achieve optimum separations? Assume there is a high speed exit for around 40 kts or more, how far from the approach end should the exit begin?
What would be the procedure for A320 and B737 or heavier types? To be more sure of making the exit, would auto brake medium be selected for landing and then released ASAP for any required manual braking when nominated high speed exit is assured?
Departures would have to be considered at some stage. How would that work on a single runway or with 2 rwys at Brisbane? Without a parallel runway are we destined to have the same holding delays in a few years when traffic increases further?
With 3 runways in operation at Zaventem, X rwy long sequences of landings have been observed, all at 3.75 - 4 nm separation, but it was very very tight if preceeding aircraft made an exit at a slower than necessary speed. A go-around was inevitable if the landing aircraft missed the high speed.
Much experience with low separation will be on airfields with wide spaced parallel runways. Anyone have low separation experience on other busy sub-standard airfields like Brisbane?
What would be the procedure for A320 and B737 or heavier types? To be more sure of making the exit, would auto brake medium be selected for landing and then released ASAP for any required manual braking when nominated high speed exit is assured?
Departures would have to be considered at some stage. How would that work on a single runway or with 2 rwys at Brisbane? Without a parallel runway are we destined to have the same holding delays in a few years when traffic increases further?
With 3 runways in operation at Zaventem, X rwy long sequences of landings have been observed, all at 3.75 - 4 nm separation, but it was very very tight if preceeding aircraft made an exit at a slower than necessary speed. A go-around was inevitable if the landing aircraft missed the high speed.
Much experience with low separation will be on airfields with wide spaced parallel runways. Anyone have low separation experience on other busy sub-standard airfields like Brisbane?
Heathrow seperation between medium jets was 2.5nm. Quite impressive to watch really. You would be at 10nm final and have two in front with another just touching down. That was the true meaning of 'minimum runway occupancy'.
Worked a treat, I had only one go-around in 6 years due to the aircraft ahead not making its turnoff. Off course there was also strategic use of 'land after' clearances and 'expect late landing clearance' instructions.
On the 320 'minimum runway' occupancy meant MED autobrake and FULL reverse EVERY landing and you would often turn to see an aircraft in the flare as you cleared the runway. I guess that is what happens when the airport is at 100% capacity.
Worked a treat, I had only one go-around in 6 years due to the aircraft ahead not making its turnoff. Off course there was also strategic use of 'land after' clearances and 'expect late landing clearance' instructions.
On the 320 'minimum runway' occupancy meant MED autobrake and FULL reverse EVERY landing and you would often turn to see an aircraft in the flare as you cleared the runway. I guess that is what happens when the airport is at 100% capacity.
Last edited by Ollie Onion; 22nd Apr 2013 at 07:56.
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Worked a treat, I had only one go-around in 6 years due to the aircraft ahead not making its turnoff.
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<<Should following aircraft make small speed adjustments based on TCAS to achieve optimum separations?>>
Definitely not. The controller is the only one who knows what spacing is required for many reasons so just follow his instructions. If you make your own adjustments by slowing down it might have serious effects on the one behind if the controller is providing wake turbulence separation. If you have a different final approach speed requirement from "usual" let ATC know in good time so they can accommodate you.
Definitely not. The controller is the only one who knows what spacing is required for many reasons so just follow his instructions. If you make your own adjustments by slowing down it might have serious effects on the one behind if the controller is providing wake turbulence separation. If you have a different final approach speed requirement from "usual" let ATC know in good time so they can accommodate you.
Should following aircraft make small speed adjustments based on TCAS to achieve optimum separations?
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"On the 320 'minimum runway' occupancy meant MED autobrake and FULL reverse..."
Max reverse or idle reverse... Autobrake provides a decelleration RATE. If you use idle rev it will brake accordingly to achieve a rate and max reverse same.. Brakes will vary accordingly to achieve a decel rate...
Min runway occupancy is med autobrake.. Idle or max rev
You'll still pull up at the same decel rate...
The only think affected is brake temperature.
Max reverse or idle reverse... Autobrake provides a decelleration RATE. If you use idle rev it will brake accordingly to achieve a rate and max reverse same.. Brakes will vary accordingly to achieve a decel rate...
Min runway occupancy is med autobrake.. Idle or max rev
You'll still pull up at the same decel rate...
The only think affected is brake temperature.
TCAS is not to be used to separate yourself from other aircraft as ATC would do in a radar environment.
It's a collision avoidance system, not a traffic separation system.
As with all controlled airspace (assuming your IFR), let ATC control your spacing and speed. That is why they have a job, otherwise the entire Australian FIR would be a CTAF.
It's a collision avoidance system, not a traffic separation system.
As with all controlled airspace (assuming your IFR), let ATC control your spacing and speed. That is why they have a job, otherwise the entire Australian FIR would be a CTAF.
The minimum spacing on final in a single runway mixed mode environment depend on aircraft type, weather (vis, base, headwind) and normal occupancy time for the arrivals and departures. You use Brisbane as an example. If you have 2 turboprops arriving and are to depart a turboprop in the gap, you're going to want a 4nm gap. If they're jets you'll need 5. And if they're heavies (apart fr the mighty 767) you want 6nm. In good weather the arrival rate will be about 24 per hr. One every 150 seconds. This equates to about 6nm gaps, and allows for one heavy, or perhaps two turboprops. In this configuration you have 24 arrivals and maybe 26 or 27 departures given a reasonable traffic mix for a total movement rate of 51 or 52 per hr.
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Definitely not. The controller is the only one who knows what spacing is required for many reasons so just follow his instructions. If you make your own adjustments by slowing down it might have serious effects on the one behind if the controller is providing wake turbulence separation. If you have a different final approach speed requirement from "usual" let ATC know in good time so they can accommodate you.
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The minimum spacing on final in a single runway mixed mode environment depend on aircraft type, weather (vis, base, headwind) and normal occupancy time for the arrivals and departures. You use Brisbane as an example. If you have 2 turboprops arriving and are to depart a turboprop in the gap, you're going to want a 4nm gap. If they're jets you'll need 5. And if they're heavies (apart fr the mighty 767) you want 6nm. In good weather the arrival rate will be about 24 per hr. One every 150 seconds. This equates to about 6nm gaps, and allows for one heavy, or perhaps two turboprops. In this configuration you have 24 arrivals and maybe 26 or 27 departures given a reasonable traffic mix for a total movement rate of 51 or 52 per hr.
Last edited by Oxidant; 22nd Apr 2013 at 10:28.
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<<Final spacing at Gatwick during normal operations is 6nm (1 in 1 out). It's even published in their unit instructions>>
Do you have any first hand experience of Gatwick 1Charlie? Yes, 6nm is employed but ATC will adjust that spacing as necessary top provide the best utilisation. If it's quiet with departures (rare, I know) they may pack a few with 3nm spacing.
Do you have any first hand experience of Gatwick 1Charlie? Yes, 6nm is employed but ATC will adjust that spacing as necessary top provide the best utilisation. If it's quiet with departures (rare, I know) they may pack a few with 3nm spacing.
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autoflight,
Each airport/runway has its own characteristics and aircraft types. Brisbane is currently single runway, but a parallel is getting there. That new runway will support simultaneous ARR and DEP operations.
Brisbane has quite a bit of heavy traffic. This makes it a bit more of a challenge for closer spacing options. The high speed exits currently in place (DC-9 era) offer little relief.
Environmentally, getting a new track approved is a very big challenge.
One scenario that may help at Brisbane is a batched diverse DEP. The DEP procedure can really only be optimized over the bay, so it would be weather dependent, but going to 400/500 feet and turning left and right, combined with a batched departure, would add a few more slots...IF environment would approve.
Each airport/runway has its own characteristics and aircraft types. Brisbane is currently single runway, but a parallel is getting there. That new runway will support simultaneous ARR and DEP operations.
Brisbane has quite a bit of heavy traffic. This makes it a bit more of a challenge for closer spacing options. The high speed exits currently in place (DC-9 era) offer little relief.
Environmentally, getting a new track approved is a very big challenge.
One scenario that may help at Brisbane is a batched diverse DEP. The DEP procedure can really only be optimized over the bay, so it would be weather dependent, but going to 400/500 feet and turning left and right, combined with a batched departure, would add a few more slots...IF environment would approve.
I'm aware Gatwick TCU is able to adjust the spacing on final to suit how many departures there are. A flexibility not enjoyed by most Australian airports as the sequence was locked in 200nm away. This standard terminal arrival setup where delay is absorbed en route was at industry request and is becoming more common. The question was how big should the arrival spacing be if there are departures in between. Do you not agree with the numbers?
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One would batch arrivals, just as you batch departures. In the morning at YBBN, if you batch DEP, then in 10 mins, you could have 10 DEP with div departure, in another 10 min, 8 ARR. If you blend DEP/ARR with the heavies, the spacing will get you far fewer movements.
This gives ac less time in terminal airspace (heavy fuel burn) and less taxi time for ac in DEP...
push 'em back, and let 'em go....
This gives ac less time in terminal airspace (heavy fuel burn) and less taxi time for ac in DEP...
push 'em back, and let 'em go....
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FPOBN,
Do you actually need environmental approval? If you do, can you go ahead anyway and force them to challenge your operation? Of course previously the ducks would have needed to be lined up for max advantage.
Do you actually need environmental approval? If you do, can you go ahead anyway and force them to challenge your operation? Of course previously the ducks would have needed to be lined up for max advantage.
Definitely not. The controller is the only one who knows what spacing is required for many reasons so just follow his instructions. If you make your own adjustments by slowing down it might have serious effects on the one behind if the controller is providing wake turbulence separation.
Last edited by Sue Ridgepipe; 23rd Apr 2013 at 01:43.