Missed Approach Climb gradient and missed approach requirements
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OBN, the chart you linked on top is for "Aerodrome Reference Code" not approach CAT. The stated approach speed is what gives the Approach CAT.(Ref Jepp Intro-chart glossary, p 2). Jepp is kind enough to seperate TERPS from ICAO CATs. TERPS uses Vref at MLW as ICAO uses Vat (speed at threshold). As for Canada, yes the text says use the actual LW Vref (which might allow to drop one notch) but the example provided is one UP. If you ever dealt with TC, you know there is a lot of "interpretation" and I would not test them on going one notch below. My operator classified each of our types as one, and only one, CAT. Makes sense to me.
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Airport Reference code is the Approach Cat and wingspan, hence the Cat C-III, with the reference speed for approach.
There is only one CAT allowed per aircraft, that is in all of the criteria.
Some States allow the pilot to use a higher CAT, depending on approach conditions.
TERPS/ICAO are design criteria for approach parameters, which include winds, aircraft cert approach speed does not. The approach speeds on final are based on Vref with a max per the CAT, it doesnt say how you get there, and MLW is not part of that...
The Aircraft certification is much different.
There is only one CAT allowed per aircraft, that is in all of the criteria.
Some States allow the pilot to use a higher CAT, depending on approach conditions.
TERPS/ICAO are design criteria for approach parameters, which include winds, aircraft cert approach speed does not. The approach speeds on final are based on Vref with a max per the CAT, it doesnt say how you get there, and MLW is not part of that...
The Aircraft certification is much different.
Last edited by FlightPathOBN; 4th Jan 2013 at 16:54.
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You are right, I am wrong about this one (my Jepp paper copy is way too old)
"The Airport Reference Code (ARC) is a coding system developed by the Federal Aviation Administration to relate airport design criteria to the operational and physical characteristics of the airplane types that will operate at a particular airport. (The ARC is part of design standards established in the FAA Advisory Circular 150/5300-13, Airport Design</I>, June 2008.) The ARC has two components relating to the airport design aircraft. The first component, depicted by a letter, is the "approach category" and is based on aircraft approach speed. The second component, depicted by a Roman numeral, is the airplane "design group" and is based on airplane wingspan."
But you are wrong about how the CAT is established (FAR 97):
(b) Aircraft approach category means a grouping of aircraft based on a speed of VREF, if specified, or if VREF is not specified, 1.3 VS0 at the maximum certificated landing weight. VREF, VS0, and the maximum certificated landing weight are those values as established for the aircraft by the certification authority of the country of registry. The categories are as follows:
(1) Category A: Speed less than 91 knots.
(2) Category B: Speed 91 knots or more but less than 121 knots.
(3) Category C: Speed 121 knots or more but less than 141 knots.
(4) Category D: Speed 141 knots or more but less than 166 knots.
(5) Category E: Speed 166 knots or more.
or ICAO:
While the speed ranges used to determine an aircraft's approach category are identical to 14 CFR 97.3 (ICAO Doc 8168 PANS-OPS Vol 1, Section 4, Paragraph 1.3.5), the maximum permitted speed for visual maneuvering is significantly higher. The method used for determining the approach category speed is slightly different: VAT = speed at threshold based on 1.3 times VS0 or 1.23 times Vs1g at maximum certificated weight. Additionally, speed ranges are specified for other segments of the approach: (ICAO Doc 8168, Vol 1, Section 4, Table I-4-1-2).
In both cases, CAT is at MLW and there is only one per aircraft(we agree on that!).
"The Airport Reference Code (ARC) is a coding system developed by the Federal Aviation Administration to relate airport design criteria to the operational and physical characteristics of the airplane types that will operate at a particular airport. (The ARC is part of design standards established in the FAA Advisory Circular 150/5300-13, Airport Design</I>, June 2008.) The ARC has two components relating to the airport design aircraft. The first component, depicted by a letter, is the "approach category" and is based on aircraft approach speed. The second component, depicted by a Roman numeral, is the airplane "design group" and is based on airplane wingspan."
But you are wrong about how the CAT is established (FAR 97):
(b) Aircraft approach category means a grouping of aircraft based on a speed of VREF, if specified, or if VREF is not specified, 1.3 VS0 at the maximum certificated landing weight. VREF, VS0, and the maximum certificated landing weight are those values as established for the aircraft by the certification authority of the country of registry. The categories are as follows:
(1) Category A: Speed less than 91 knots.
(2) Category B: Speed 91 knots or more but less than 121 knots.
(3) Category C: Speed 121 knots or more but less than 141 knots.
(4) Category D: Speed 141 knots or more but less than 166 knots.
(5) Category E: Speed 166 knots or more.
or ICAO:
While the speed ranges used to determine an aircraft's approach category are identical to 14 CFR 97.3 (ICAO Doc 8168 PANS-OPS Vol 1, Section 4, Paragraph 1.3.5), the maximum permitted speed for visual maneuvering is significantly higher. The method used for determining the approach category speed is slightly different: VAT = speed at threshold based on 1.3 times VS0 or 1.23 times Vs1g at maximum certificated weight. Additionally, speed ranges are specified for other segments of the approach: (ICAO Doc 8168, Vol 1, Section 4, Table I-4-1-2).
In both cases, CAT is at MLW and there is only one per aircraft(we agree on that!).
Flightpath OBN, I'm a bit worried that in your position as an approach designer you seem to have little understanding of how approach categories are determined. It's got nothing to do with the manufacturer. Have you actually read AIP ENR 1.5 1.2.1? Its the Vat at MLW with Landing flap. Period.
Last edited by Capn Bloggs; 4th Jan 2013 at 21:52.
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cleveland...
you had it close, but read the regs very closely...
and I know exactly how each aircraft CAT is determined, and how is is different that the procedure design CAT designation
Boeing and Airbus both specify Vref, for the certification process...and they way they do it is the secret sauce....if it was just Vref at MLW, then what were the flap settings? What about winds?
note: "or if VREF is not specified, 1.3 VS0 at the maximum certificated landing weight."
"VAT = speed at threshold based on 1.3 times VS0 or 1.23 times Vs1g at maximum certificated weight."
The Boeing table illustrates this how this is calculated very well...
From Boeing Airport reference code, D-III ref approach speed. 142 kts
from the 800 QRH MLW 73T
flaps 40 151 kts
flaps 30 158 kts
flaps 15 167 kts
From Boeing Airport reference code, D-III ref approach speed. 142 kts, so if you were designing a procedure for a 737-800...would you use the Boeing data, or the criteria data?
The Airport Reference Code (ARC) is a coding system developed by the Federal Aviation Administration to relate airport design criteria to the operational and physical characteristics of the airplane types that will operate at a particular airport. (The ARC is part of design standards established in the FAA Advisory Circular 150/5300-13A)
The ARC has two components relating to the airport design aircraft. The first component, depicted by a letter, is the "approach category" and is based on aircraft approach speed. The second component, depicted by a Roman numeral, is the airplane "design group" and is based on airplane wingspan.
Here is ICAO definition of Vref:
1.3 times the stalling speed in the stated landing configuration and at the prevailing aircraft weight. This is the speed required as the landing runway threshold is crossed at 50 feet height if calculated aircraft performance is to be achieved.
and then there is the reference stall speed VSR and 1.23 VSR
you had it close, but read the regs very closely...
and I know exactly how each aircraft CAT is determined, and how is is different that the procedure design CAT designation
Boeing and Airbus both specify Vref, for the certification process...and they way they do it is the secret sauce....if it was just Vref at MLW, then what were the flap settings? What about winds?
note: "or if VREF is not specified, 1.3 VS0 at the maximum certificated landing weight."
"VAT = speed at threshold based on 1.3 times VS0 or 1.23 times Vs1g at maximum certificated weight."
The Boeing table illustrates this how this is calculated very well...
From Boeing Airport reference code, D-III ref approach speed. 142 kts
from the 800 QRH MLW 73T
flaps 40 151 kts
flaps 30 158 kts
flaps 15 167 kts
From Boeing Airport reference code, D-III ref approach speed. 142 kts, so if you were designing a procedure for a 737-800...would you use the Boeing data, or the criteria data?
The Airport Reference Code (ARC) is a coding system developed by the Federal Aviation Administration to relate airport design criteria to the operational and physical characteristics of the airplane types that will operate at a particular airport. (The ARC is part of design standards established in the FAA Advisory Circular 150/5300-13A)
The ARC has two components relating to the airport design aircraft. The first component, depicted by a letter, is the "approach category" and is based on aircraft approach speed. The second component, depicted by a Roman numeral, is the airplane "design group" and is based on airplane wingspan.
Here is ICAO definition of Vref:
1.3 times the stalling speed in the stated landing configuration and at the prevailing aircraft weight. This is the speed required as the landing runway threshold is crossed at 50 feet height if calculated aircraft performance is to be achieved.
and then there is the reference stall speed VSR and 1.23 VSR
Last edited by FlightPathOBN; 4th Jan 2013 at 22:27.
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If you use the Boeing chart, you will notice that the MLW giving that 142 kt is 66.3T. I don't fly the 737, so I can't tell. But the other types I have flown have the MLW as stated on that chart (and matching CAT); why would the 738 be different? Any 738 driver with a MLW higher than 66.3T?
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from Boeing chart MLW for the 737-800 is 146300, in the US, this is 73.15 tons?
Here is the Vref table from the 800 QRH..
Note flaps/speeds for 73.15T.. where does 142kts fit in with MLW?
Here is the Vref table from the 800 QRH..
Note flaps/speeds for 73.15T.. where does 142kts fit in with MLW?
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If we go back to the original question CAT.
As we can see Boeing has a reference CAT for each aircraft, and the State uses this.
In the example for the 737-800, you CAN, at 50T, flaps 30, have a Vref of 129kts...this does not mean you can use a CAT C approach.
The actual aircraft, depending on configuration, will have its own certified MLW.
For approach procedure design, the segment speeds will have winds added...
Some regulators require ground speed for the procedure designs as well...
The 737-800 is a CAT D. Some airlines, will play with the weights and configuration, to get the aircraft to certified by the Boeing/State to CAT C for access, or to limit loading to save landing fees, etc.
As we can see Boeing has a reference CAT for each aircraft, and the State uses this.
In the example for the 737-800, you CAN, at 50T, flaps 30, have a Vref of 129kts...this does not mean you can use a CAT C approach.
The actual aircraft, depending on configuration, will have its own certified MLW.
For approach procedure design, the segment speeds will have winds added...
Some regulators require ground speed for the procedure designs as well...
The 737-800 is a CAT D. Some airlines, will play with the weights and configuration, to get the aircraft to certified by the Boeing/State to CAT C for access, or to limit loading to save landing fees, etc.
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just to clarify: 146300 lbs = 66361 kg = 73.15 short ton = 66.3 metric tonne
The Boeing chart give both the imperial/US weight (MLW 146300) and metric weight (MLW 66361kg).
The QRH chart you provide is METRIC. You can't enter your QRH chart with non-metric data.
The Boeing chart give both the imperial/US weight (MLW 146300) and metric weight (MLW 66361kg).
The QRH chart you provide is METRIC. You can't enter your QRH chart with non-metric data.
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Good morning all,
I’ve read now pretty much all the threads on pprune regarding gradients, acceleration, flap retraction & thrust reduction during the missed approach OEI & AEO.
I especially enjoyed and learned alot from many posts from tullamarine, aterpster, opendes, flightpathobn, rudddrrudderrat and others. Thank you for that!
Anyway, some questions haven’t been answered jet: Is the 2.4% gradient an average? tullamarine mentioned in one of his posts, that it depends on the source one is referring to and maybe on the understanding or translation of the words…In my case, I would refer to Pans Ops I&II and EASA (as I’m working for a german operator), where it says in the construction part that the gradient is a nominal gradient (tan Z). Therefore I don’t think it’s average?!?
If it’s not average, and it needs to be met during the intermediate and final missed approach phase (because the approach is construced so), that gradient should be calculated (by the pilot) at the missed approach altitude or the defined altitude on the IAC. So what is the sense in LPCNG and AI documentation in computing the gradient at airport pressure level?
In my previous outfit, credo was (a bit simplyfied): - missed approach all engines operating: published, reduce thrust, accelerate and clean up at missed approach altitude, MSA, or published acceleration altitude (e.g. many french airports), whichever comes first.
- missed approach OEI: follow (take off-) engine fail procedure, reduce thrust, accelerate and clean up at missed approach altitude, MSA or published acceleration altitude (e.g. many french airports), whichever comes first.
In my opinion, that was quite solid, as our ops engineers analysed all runways, etc. to develop the engine fail routings…
Hole different story in my new company…they let the pilots the choise between published and EFP, no mention at all of acceleration and thrust reduction altitudes in any books, and so on. Hence imho even more important to know for the pilots the calculation methods and requirements behind all that stuff to be able to determine whether I can fly the approach or not, where to accelerate and to reduce and which go around procedure to follow in case of…
So the 2nd the question: If the IAC says „using XXX minimum, 3.5% required up to 3000ft“, in my opinion, in LPCNG, the gradient should be calculated at 3000ft and consequently thrust reduction and acceleration should be at 3000ft?!?
One last thing, I found that those kind of question appear here on pprune and in other forums evers 4 years or so. Is that a lack of good education ;-)
Thank you all!
I’ve read now pretty much all the threads on pprune regarding gradients, acceleration, flap retraction & thrust reduction during the missed approach OEI & AEO.
I especially enjoyed and learned alot from many posts from tullamarine, aterpster, opendes, flightpathobn, rudddrrudderrat and others. Thank you for that!
Anyway, some questions haven’t been answered jet: Is the 2.4% gradient an average? tullamarine mentioned in one of his posts, that it depends on the source one is referring to and maybe on the understanding or translation of the words…In my case, I would refer to Pans Ops I&II and EASA (as I’m working for a german operator), where it says in the construction part that the gradient is a nominal gradient (tan Z). Therefore I don’t think it’s average?!?
If it’s not average, and it needs to be met during the intermediate and final missed approach phase (because the approach is construced so), that gradient should be calculated (by the pilot) at the missed approach altitude or the defined altitude on the IAC. So what is the sense in LPCNG and AI documentation in computing the gradient at airport pressure level?
In my previous outfit, credo was (a bit simplyfied): - missed approach all engines operating: published, reduce thrust, accelerate and clean up at missed approach altitude, MSA, or published acceleration altitude (e.g. many french airports), whichever comes first.
- missed approach OEI: follow (take off-) engine fail procedure, reduce thrust, accelerate and clean up at missed approach altitude, MSA or published acceleration altitude (e.g. many french airports), whichever comes first.
In my opinion, that was quite solid, as our ops engineers analysed all runways, etc. to develop the engine fail routings…
Hole different story in my new company…they let the pilots the choise between published and EFP, no mention at all of acceleration and thrust reduction altitudes in any books, and so on. Hence imho even more important to know for the pilots the calculation methods and requirements behind all that stuff to be able to determine whether I can fly the approach or not, where to accelerate and to reduce and which go around procedure to follow in case of…
So the 2nd the question: If the IAC says „using XXX minimum, 3.5% required up to 3000ft“, in my opinion, in LPCNG, the gradient should be calculated at 3000ft and consequently thrust reduction and acceleration should be at 3000ft?!?
One last thing, I found that those kind of question appear here on pprune and in other forums evers 4 years or so. Is that a lack of good education ;-)
Thank you all!
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Hi, can I was searching for info about how to calculate the relation between the missed approach % and the V/S. It seems you know how to calculate using the Vapp, can you tell me how to do it?.
Much appreciated,
Camilo Orduz.
Much appreciated,
Camilo Orduz.
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ROD (fpm) = % Gradient X Ground Speed (Knots)
Another way is to find an appropriate conversion table in your OM-C, eg. Jeppesen, Lido...
Moderator
The simple formula is: ROD (fpm) = % Gradient X Ground Speed (Knots)
Minor side note for completeness. While the formula cited is used generally and is fine for pragmatic purposes, when one runs the unit conversions, there is around a 1 % error involved. This, normally, is ignored. However, just as well to be aware of the consideration.
Regarding varying the cat, I am rather amazed that folks might want to reduce cat limits with a weight reduction. I was always quite happy to adopt a higher cat on the jets (especially for nastier aerodromes) as that made everything a lot more comfortable ... just meant we didn't get in on occasion. Cost of doing business in my simple view of life.
Minor side note for completeness. While the formula cited is used generally and is fine for pragmatic purposes, when one runs the unit conversions, there is around a 1 % error involved. This, normally, is ignored. However, just as well to be aware of the consideration.
Regarding varying the cat, I am rather amazed that folks might want to reduce cat limits with a weight reduction. I was always quite happy to adopt a higher cat on the jets (especially for nastier aerodromes) as that made everything a lot more comfortable ... just meant we didn't get in on occasion. Cost of doing business in my simple view of life.
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The solution being...
a third pilot in the flight deck with a sextant, an independent GPS unit, hard copies of relevant regulations and instrument approach constructions for every airport that will be used, a thermos of coffee, a couple of marmite sandwhiches, a slide ruler in his white shirt pocket, along with 6 ink pens and 6 pencils, a spare set of eye glasses and a pair of dice to calculate the chance of success for each takeoff, approach and missed approach. 😀
Regarding varying the cat, I am rather amazed that folks might want to reduce cat limits with a weight reduction. I was always quite happy to adopt a higher cat on the jets (especially for nastier aerodromes) as that made everything a lot more comfortable ... just meant we didn't get in on occasion. Cost of doing business in my simple view of life.
In the USAF, the jet I flew was a Cat D aircraft, however we flew many circling approaches as well as circling No-Flap approaches. When flying a No-Flap approach, if our approach speed exceeded 165 Knots which mandated we use the CAT E minimums on the approach plate. So even though we were a CAT D aircraft we changed our category depending on our approach speed for the maneuver being flown.
As far as missed approaches and the 2.5 degree climb gradient, my airline has “special engine out” procedures for airports whose terrain will not support a “straight out “ missed approach procedure flown at a 2.5 degree climb gradient. In these cases a special engine out procedure is designed to avoid terrain in an engine out scenario. Also we are required in the event of an engine out approach to check our engine out climb gradient. If the gradient exceeds the minimum required for the normal missed approach procedure we can fly the MAP as published on the approach plate. However, if the min climb gradient, engine out, is less than the published MAP procedure ( based on all engines operating) then we have to fly the special engine out procedure in lieu of the published missed approach procedure. We are further required to let ATC know our intentions, as we are told that ATC may not know what our company designed Special eng out procedure is.
As far as missed approaches and the 2.5 degree climb gradient, my airline has “special engine out” procedures for airports whose terrain will not support a “straight out “ missed approach procedure flown at a 2.5 degree climb gradient. In these cases a special engine out procedure is designed to avoid terrain in an engine out scenario. Also we are required in the event of an engine out approach to check our engine out climb gradient. If the gradient exceeds the minimum required for the normal missed approach procedure we can fly the MAP as published on the approach plate. However, if the min climb gradient, engine out, is less than the published MAP procedure ( based on all engines operating) then we have to fly the special engine out procedure in lieu of the published missed approach procedure. We are further required to let ATC know our intentions, as we are told that ATC may not know what our company designed Special eng out procedure is.
