Aircraft Approach Category
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Aircraft Approach Category
Hi all,
Yesterday, while flying, we had a discussion in the cockpit about Aircraft Approach Category with reference to the following points, and I would LOVE to hear/read your opinions and ideas about it.
Here are some of the questions and points we discussed and explored:
1.The way the info is depicted on Jeppesen charts:
- Category letter designation on the bottom-left Vs.max. airspeeds on the bottom right.
- Are the airspeeds TAS or GS?
- Is there correlation between the letters on the Left side and the max speeds on the Right side? (I claimed there is but I couldn't find any text explaining that, not even in the Jepp. Introduction. But I do remember many years ago I read it. maybe in a text book...)
2. TERPS vs. PANS-OPS. with regards to theory and practice:
- The differences and between them and their meanings.
- What should we pay attention to as pilots when we brief an approach plate? (specially if some of your airline's destinations have TERPS plates and some have PANS-OPS)?
- What happens when operating at higher speeds than depicted (in both TERPS & PANS-OPS)? Should I operate according to the speed of a higher category? Shall I use a higher minima according to the "new" higher category?
- And what happens if I decide to fly part of the approach at high speed and the rest in lower speed?
3. Types of charts that the Aircraft Approach Category applies to:
- Does it only apply for Circle to Land maneuvers or for all approach types?
4. The correct way to operate the aircraft:
PANS-OPS - Since different speeds are assumed for different phazes of the approach, should I memorize the airspeed limits of the categories in every approach phaze (Initial approach, Final approach, Circle to Land, Missed Approach, etc..)?
5. How do you operate your aircraft? Do you even care about all that?
Yesterday, while flying, we had a discussion in the cockpit about Aircraft Approach Category with reference to the following points, and I would LOVE to hear/read your opinions and ideas about it.
Here are some of the questions and points we discussed and explored:
1.The way the info is depicted on Jeppesen charts:
- Category letter designation on the bottom-left Vs.max. airspeeds on the bottom right.
- Are the airspeeds TAS or GS?
- Is there correlation between the letters on the Left side and the max speeds on the Right side? (I claimed there is but I couldn't find any text explaining that, not even in the Jepp. Introduction. But I do remember many years ago I read it. maybe in a text book...)
2. TERPS vs. PANS-OPS. with regards to theory and practice:
- The differences and between them and their meanings.
- What should we pay attention to as pilots when we brief an approach plate? (specially if some of your airline's destinations have TERPS plates and some have PANS-OPS)?
- What happens when operating at higher speeds than depicted (in both TERPS & PANS-OPS)? Should I operate according to the speed of a higher category? Shall I use a higher minima according to the "new" higher category?
- And what happens if I decide to fly part of the approach at high speed and the rest in lower speed?
3. Types of charts that the Aircraft Approach Category applies to:
- Does it only apply for Circle to Land maneuvers or for all approach types?
4. The correct way to operate the aircraft:
PANS-OPS - Since different speeds are assumed for different phazes of the approach, should I memorize the airspeed limits of the categories in every approach phaze (Initial approach, Final approach, Circle to Land, Missed Approach, etc..)?
5. How do you operate your aircraft? Do you even care about all that?
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Some good reference material
Here is some good reference reading material about the subject.
Feel free to post and share more references.
1. SKYbrary - Circling Approach - difference between ICAO PANS-OPS and US TERPS
2. Jeppesen Introduction - Glossay - Aircraft Approach Category
3. ICAO DOC 8168 vol 1. can be found in the Jeppesen Airway Manual (see Table I-4-1-2 as a starting point and explore around it)
4. FAA AIM 5-4-7 a. (page 5-4-26): http://www.faa.gov/air_traffic/publi...c_2-9-2012.pdf
Feel free to post and share more references.
1. SKYbrary - Circling Approach - difference between ICAO PANS-OPS and US TERPS
2. Jeppesen Introduction - Glossay - Aircraft Approach Category
3. ICAO DOC 8168 vol 1. can be found in the Jeppesen Airway Manual (see Table I-4-1-2 as a starting point and explore around it)
4. FAA AIM 5-4-7 a. (page 5-4-26): http://www.faa.gov/air_traffic/publi...c_2-9-2012.pdf
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Aviatorhi,
I'm not sure I understood what you meant but in both TERPS and PANS-OPS the Aircraft Approach Category is determined only with reference to speeds and not to size. The size of the aircraft is only being taken into account by PANS-OPS to determine the OCA for Precision Approaches - thus determining the DA. Not the Aircraft's Approach Category. Check out the following quotes:
1. TERPS: (taken from FAA FAR 97.3):
2. PANS-OPS: (taken from ICAO doc. 8168 which can be found in Jeppesen Airway Manual p. 525):
I'm not sure I understood what you meant but in both TERPS and PANS-OPS the Aircraft Approach Category is determined only with reference to speeds and not to size. The size of the aircraft is only being taken into account by PANS-OPS to determine the OCA for Precision Approaches - thus determining the DA. Not the Aircraft's Approach Category. Check out the following quotes:
1. TERPS: (taken from FAA FAR 97.3):
Aircraft approach category means a grouping of aircraft based on a speed of VREF, if specified, or if VREF is not specified, 1.3 Vso at the maximum certificated landing weight.
2. PANS-OPS: (taken from ICAO doc. 8168 which can be found in Jeppesen Airway Manual p. 525):
1.3 CATEGORIES OF AIRCRAFT
1.3.1 Aircraft performance has a direct effect on the airspace and visibility required for the various manoeu- vres associated with the conduct of instrument approach procedures. The most significant performance factor is aircraft speed.
1.3.2 These categories provides a standardized basis for relating aircraft manoeuvrability to specific instru- ment approach procedures. For precision approach procedures, the dimensions of the aircraft are also a factor for the calculation of the obstacle clearance height (OCH). For Category DL aircraft, an additional obstacle clear- ance altitude/height (OCA/H) is provided, when necessary, to take into account the specific dimensions of these aircraft.
1.3.3 The criterion taken into consideration for the classification of aeroplanes by categories is the indicated airspeed at threshold (Vat ), which is equal to the stall speed Vso multiplied by 1.3, or stall speed Vslg multiplied by 1.23 in the landing configuration at the maximum certificated landing mass. If both Vso and Vslg are available, the higher resulting Vat shall be applied.
1.3.1 Aircraft performance has a direct effect on the airspace and visibility required for the various manoeu- vres associated with the conduct of instrument approach procedures. The most significant performance factor is aircraft speed.
1.3.2 These categories provides a standardized basis for relating aircraft manoeuvrability to specific instru- ment approach procedures. For precision approach procedures, the dimensions of the aircraft are also a factor for the calculation of the obstacle clearance height (OCH). For Category DL aircraft, an additional obstacle clear- ance altitude/height (OCA/H) is provided, when necessary, to take into account the specific dimensions of these aircraft.
1.3.3 The criterion taken into consideration for the classification of aeroplanes by categories is the indicated airspeed at threshold (Vat ), which is equal to the stall speed Vso multiplied by 1.3, or stall speed Vslg multiplied by 1.23 in the landing configuration at the maximum certificated landing mass. If both Vso and Vslg are available, the higher resulting Vat shall be applied.
Last edited by yonygg; 29th Jul 2013 at 09:29.
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Aircraft approach category is determined during the certification process and remains fixed.
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As I understand it, your straight in category is determined by 1.3 Vso or Vref for your aircraft at Max certificated gross Weight. For circling it is 1.3 Vso or Vref for the actual aircraft gross weight.
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The way I understand it is that your category never changes from the category that was determined by the operator (based on the certification of the plane) and approved by the regulator, and is solely based on your Stall Speed (generally speaking 1.3*Vso), BUT:
1. When you fly a TERPS approach, when ever you are flying faster than your category's max. speed (either on a straight-in or circling approach) and on ANY segment of the approach, **IF YOU WANT TO STAY PROTECTED FROM OBSTACLES -USE A THE HIGHER RELEVANT APPROACH MINIMA OR PRESCRIBED PROCEDURE ACCORDING TO YOUR *"NEW" CURRENT SPEED.
Also if you are a Category A or B aircraft on a circling approach don't use less than 25 degs. of bank angle IF YOU WANT TO STAY WITHIN THE PROTECTED AREA.
2. When you fly a PANS-OPS approach it's a different story -
Every segment of the approach has an ASSUMED speed that the Pans-Ops people assumed you would fly, based on your certified category. (The assumed speeds can be found here for reference only. If you are looking for an official reference open ICAO doc. 8168).
In case you fly faster than your "assumed" speed - USE THE HIGHER RELEVANT APPROACH MINIMA OR PRESCRIBED PROCEDURE ACCORDING TO YOUR *NEW SPEED FOR THAT SEGMENT - **ONLY IF YOU WANT TO STAY PROTECTED.
And yes- that requires us to know these assumed speeds for our aircraft's category by heart and to go over the "TERPS/PANS-OPS" note on the Jepp. chart and it's meaning during the approach briefing!
* And the reason for flying faster does NOT matter - wether you have a flaps malfunction or ATC requested you to perform a high speed approach, or you just don't want to miss your favorite TV show
** Wether you want to stay protected or not is really up to you. If you have difficulties decide ask your pax for their preference - they will give you a very clear answer...
1. When you fly a TERPS approach, when ever you are flying faster than your category's max. speed (either on a straight-in or circling approach) and on ANY segment of the approach, **IF YOU WANT TO STAY PROTECTED FROM OBSTACLES -USE A THE HIGHER RELEVANT APPROACH MINIMA OR PRESCRIBED PROCEDURE ACCORDING TO YOUR *"NEW" CURRENT SPEED.
Also if you are a Category A or B aircraft on a circling approach don't use less than 25 degs. of bank angle IF YOU WANT TO STAY WITHIN THE PROTECTED AREA.
2. When you fly a PANS-OPS approach it's a different story -
Every segment of the approach has an ASSUMED speed that the Pans-Ops people assumed you would fly, based on your certified category. (The assumed speeds can be found here for reference only. If you are looking for an official reference open ICAO doc. 8168).
In case you fly faster than your "assumed" speed - USE THE HIGHER RELEVANT APPROACH MINIMA OR PRESCRIBED PROCEDURE ACCORDING TO YOUR *NEW SPEED FOR THAT SEGMENT - **ONLY IF YOU WANT TO STAY PROTECTED.
And yes- that requires us to know these assumed speeds for our aircraft's category by heart and to go over the "TERPS/PANS-OPS" note on the Jepp. chart and it's meaning during the approach briefing!
* And the reason for flying faster does NOT matter - wether you have a flaps malfunction or ATC requested you to perform a high speed approach, or you just don't want to miss your favorite TV show
** Wether you want to stay protected or not is really up to you. If you have difficulties decide ask your pax for their preference - they will give you a very clear answer...
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Circling approach
I remember at Busan (Pusan) sometimes a circling approach was required from an ILS due tailwind. On that chart there were various circling minima based on specified circling speeds. In that case the landing weight directly impacted on the minima. During marginal weather, it was therefore necessary to carefully consider how much extra fuel was carried if it resulted in an increased minima. At typical circling speed for an A321, the minima was 700 ft. At higher weights it went up to about 1100 ft. That increase could easy make the difference between getting in or not.
I also recall a poor understanding of this unusual chart presentation by most expat and local crew. Almost all chose a fixed 700 ft, thinking that the limitation was actually somehow related to aircraft category.
This approach is demanding. There are traps that caught Air China. An excellent description can be found by googling "circling accident case study air china 129".
13 days before that accident, I emailed the Korean Aviation Authority with a warning about the presentation of the circling part of the approach. Even if they planned to take notice, which I doubt, that is probably insufficient time to act.
There has to be a lesson here about pre-emptive action and aggressive interpretation of approach procedures. In this case it is not good enough to just rely on a ordinary study of the chart before descent.
I also recall a poor understanding of this unusual chart presentation by most expat and local crew. Almost all chose a fixed 700 ft, thinking that the limitation was actually somehow related to aircraft category.
This approach is demanding. There are traps that caught Air China. An excellent description can be found by googling "circling accident case study air china 129".
13 days before that accident, I emailed the Korean Aviation Authority with a warning about the presentation of the circling part of the approach. Even if they planned to take notice, which I doubt, that is probably insufficient time to act.
There has to be a lesson here about pre-emptive action and aggressive interpretation of approach procedures. In this case it is not good enough to just rely on a ordinary study of the chart before descent.
Last edited by autoflight; 30th Jul 2013 at 13:35.
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Autoflight, but where do you learn these things?
I don't remember someone had ever thought me this knowledge. Not in flight academy and not in the airlines. I just decided to investigate on it and dig deep.
It's only natural that pilots interpret approach charts like the wish to if they don't have the knowledge or even a hint.
Most people I have spoken with don't know the difference between the TERPS and the PANS-OPS plates and they all interpret it "aggressively".
That's unfortunate...
I don't remember someone had ever thought me this knowledge. Not in flight academy and not in the airlines. I just decided to investigate on it and dig deep.
It's only natural that pilots interpret approach charts like the wish to if they don't have the knowledge or even a hint.
Most people I have spoken with don't know the difference between the TERPS and the PANS-OPS plates and they all interpret it "aggressively".
That's unfortunate...
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There is a difference in the interpretation of the criteria:
TERPS CAT C: 140 kts max for final approach segment, based on Vref or (1.3Vso), and 140 kts max for circling.
PANS-OPS CAT C: 140 kts based on speed at threshold (Vat), 160 kts max for final approach segment, and 180 kts max for circling.
The aircraft manufacturer provides the airport reference and CAT specification, however, your airline SOP may modify this.
Airport Reference Code and Approach Speeds for Boeing Airplanes
Edit stuff: To the original post, the reference speeds are TAS. TERPS turns assume a MAX bank angle of 18 degrees.
TERPS CAT C: 140 kts max for final approach segment, based on Vref or (1.3Vso), and 140 kts max for circling.
PANS-OPS CAT C: 140 kts based on speed at threshold (Vat), 160 kts max for final approach segment, and 180 kts max for circling.
The aircraft manufacturer provides the airport reference and CAT specification, however, your airline SOP may modify this.
Airport Reference Code and Approach Speeds for Boeing Airplanes
Edit stuff: To the original post, the reference speeds are TAS. TERPS turns assume a MAX bank angle of 18 degrees.
Last edited by underfire; 6th Aug 2013 at 14:37.
