Circling Approach rules
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Circling Approach rules
Last company I worked for had SOP to adjust the downwind leg timing of Circling Approaches for wind.
Also added 50ft to MDA.
Company I now work for says no need to adjust for wind effect as a tailwind allowance of up to 25kts is built into the Airbus Circling SOP.
Also say no need to add 50ft to MDA due to level off for circling.
Any thoughts? Who's right?
Also added 50ft to MDA.
Company I now work for says no need to adjust for wind effect as a tailwind allowance of up to 25kts is built into the Airbus Circling SOP.
Also say no need to add 50ft to MDA due to level off for circling.
Any thoughts? Who's right?
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Not knowing the AB SOP I can't comment about the adjustment for tailwind on downwind. Much will depend on what you're trying to achieve. If the target is to roll out on finals on GP, rather than below it, then surely tailwind will affect ground speed and therefore distance flown in a time and would need correcting.
Regarding MDA +50': MDA = never go below altitude. I assume the MDA set for the approach is rounded up from the actual MDA e.g. 576'(chart) = 600' set. Therefore the a/c does not bust the MDA, so why add any extra?
Regarding MDA +50': MDA = never go below altitude. I assume the MDA set for the approach is rounded up from the actual MDA e.g. 576'(chart) = 600' set. Therefore the a/c does not bust the MDA, so why add any extra?
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Folks,
Re. timing, the procedure design is based on a maximum radius, based on aircraft category, you must stay withing the maximum radius, period.
Re. adding increments to charted minima, not enough information, the answer can vary by country.
Tootle pip!!
Re. timing, the procedure design is based on a maximum radius, based on aircraft category, you must stay withing the maximum radius, period.
Re. adding increments to charted minima, not enough information, the answer can vary by country.
Tootle pip!!
Also say no need to add 50ft to MDA due to level off for circling.
Out of interest, what is the AB Circling procedure?
I have had trainers recommend flying 50' above the MDA when hand flying a circling approach simply to allow for minor deviations in your altitude holding. Maybe it stems from that mindset?
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The requirement to add 50ft. for NPAs is there only because in case of a GA you loose 50ft before the aircraft starts to climb. Circling approach comes out of an instrument approach but with a circling minima which is always higher than the NPA minima. If you go missed at circling minima you do not breach NPA minima. Adding another 50ft to the already higher minima could result in a GA instead of a successful landing. Airbus does not teach to add 50ft. If it is regulatory requirement it is up to the operator to do so. Timing is required but it is only a guide. It is a visual manoeuvre run way must be kept in sight at all times turn early if required.
Last edited by vilas; 28th Jul 2016 at 11:36.
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Company I now work for says no need to adjust for wind effect as a tailwind allowance of up to 25kts is built into the Airbus Circling SOP.
http://www.ukfsc.co.uk/files/Safety%...uly%202011.pdf
"5.4. Timing for Circling:
The timing Airbus recommends is
30 seconds from wings level, adjusted
for strong Head or Tail wind,
by reference to the ND wind indicator.
However, this is a visual exercise:
Timings are approximate only."
I agree with the previous comments. Adding 50ft to the MDA only applies in the case of a CDFA, to avoid descending below MDA in the event of a missed approach. The 50ft additive is not required by all regulators, and I have never heard of it being applied to the circling minima. Seems a bit pointless for a circling approach, as others have already said.
Regarding wind corrections, my understanding is that the turn radius used to calculate the circling area is based on the aircraft's TAS plus a 25kt wind factor. The circling area is then defined by a radius that is twice the turn radius plus a fixed straight segment, centred on the runway thresholds.
The 25kt wind factor is only used for the purpose of calculating the circling area. When flying the approach you still need to turn base at the correct point on the ground and adjust the downwind timing accordingly. In nil wind that point is typically 3sec/100ft of altitude. For example, if circling at 1000ft in nil wind, the base turn point would occur 30 seconds after passing abeam the landing threshold. The turn point needs to be corrected for wind to ensure the aircraft turns at the correct point.
Regarding wind corrections, my understanding is that the turn radius used to calculate the circling area is based on the aircraft's TAS plus a 25kt wind factor. The circling area is then defined by a radius that is twice the turn radius plus a fixed straight segment, centred on the runway thresholds.
The 25kt wind factor is only used for the purpose of calculating the circling area. When flying the approach you still need to turn base at the correct point on the ground and adjust the downwind timing accordingly. In nil wind that point is typically 3sec/100ft of altitude. For example, if circling at 1000ft in nil wind, the base turn point would occur 30 seconds after passing abeam the landing threshold. The turn point needs to be corrected for wind to ensure the aircraft turns at the correct point.
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The timing debate rages on at my outfit. As others have mentioned - it is a visual manoeuvre with the final turn to be commended at when the a/c is at 45 degrees to the final approach or runway track.
On Airbus, another way of helping with this is a fix info line as a radial from the landing runway threshold, 45 degrees off. When the aircraft crosses the line, it's time turn. Particularly helpful if the runway lies on the other side to which the PF is sat, and PM happens to be busy (copy active instead of activate sec, anyone?)
Just another guide, and helps with overa SA.
On Airbus, another way of helping with this is a fix info line as a radial from the landing runway threshold, 45 degrees off. When the aircraft crosses the line, it's time turn. Particularly helpful if the runway lies on the other side to which the PF is sat, and PM happens to be busy (copy active instead of activate sec, anyone?)
Just another guide, and helps with overa SA.
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i was wondering if I'm in a cat c a/c for circling but the approach speed Im using puts me in category d speeds, do I still fly cat c mins or cat d?
The 50ft additive is not required by all regulators, and I have never heard of it being applied to the circling minima
If you are on final, and decide to go missed, between the decision to do this, change config, and the ability of the aircraft to actually go from approach to climb, lets say that you decide at DA to go missed, and change config?I think most would find that the 50 foot descent is not actually obtainable.
Even if you decided in advance to go missed, you have to follow the approach profile. You then have to figure out when to go missed based on the conditions. What basis for this are you using?
Lets take a real life scenario, you are in a cat d aircraft positioning for the ILS 01 at Dalaman and the tailwind goes out of limits as the sea breeze kicks in. The circling minimum is 2310 and the tower offers you a circle to land west of the field onto 19. It is a bit hazy with unforecast CBs building nicely on the terrain to the north of the field and you have flight plan fuel. How would you fly this, assuming you briefed for this possibility in advance?
MDA is the MDA, you cannot bust this surface. When on final, you have to include momentary descent, whatever that is for your ac and conditions. It is not necessary 50 feet, the operator is required to calculate this based on the conditions.
If you are on final, and decide to go missed, between the decision to do this, change config, and the ability of the aircraft to actually go from approach to climb, lets say that you decide at DA to go missed, and change config?I think most would find that the 50 foot descent is not actually obtainable.
In the flight crew techniques manual Airbus says the level off shall not be lower than MDA(H) by pressing the ALT pb. You are in flap 3 gear down, possibly doing over 1000 fpm with a tailwind, the technique adopted by some is to add 50' to the MDA so when you press alt at the programmed MDA you will not bust the charted MDA.
They recommend 3"/100 ft above the runway abeam the threshold, but then go on to say that is for ICAO PAN-OPS and JAR OPS. For FAA or Japan TERPS refer to company SOP.
They recommend 3"/100 ft above the runway abeam the threshold, but then go on to say that is for ICAO PAN-OPS and JAR OPS. For FAA or Japan TERPS refer to company SOP.
In the flight crew techniques manual Airbus says the level off shall not be lower than MDA(H) by pressing the ALT pb. You are in flap 3 gear down, possibly doing over 1000 fpm with a tailwind, the technique adopted by some is to add 50' to the MDA so when you press alt at the programmed MDA you will not bust the charted MDA.
They recommend 3"/100 ft above the runway abeam the threshold, but then go on to say that is for ICAO PAN-OPS and JAR OPS. For FAA or Japan TERPS refer to company SOP.
They recommend 3"/100 ft above the runway abeam the threshold, but then go on to say that is for ICAO PAN-OPS and JAR OPS. For FAA or Japan TERPS refer to company SOP.