LVTO: RVR reduction to 125m
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Well, we're getting there. What have we got so far?
In this case 1 you took the liberty to assess the initial RVR and replaced the lower reported one with the one suits you.
In case 2 you say can't replace 100 with my assessment of 125M.
Case 3 NO RVR is replaced with your assessment.
Summary: in all 3 cases pilot conducted the assessment of the initial RVR but for some reasons decided not to replace the reported value with his/her own in case 2. If 125 can be assessed and replace NO RVR reported it's logical that it can be assessed any time regardless of reported RVR. Finally reported RVR 125, below the minimum, was replaced by pilot assessment of RVR 150. Why can't you replace 100 with 125 if you see 8 CL? NO reported RVR or RVR reported below the minima is still a replacement regardless how you twist it. 125 M is a magic number here it seems. Why? It is indeed for EU OPS folks as they believe it provides reasonable assurance that the pilot having 90 VS with RVR 125M will have sufficient time to react and visual cues in both cases RTO and TO to keep the aircraft within the certification confinement 30 ft off the centerline by looking outside. RVR isn't panacea but a reasonable mitigation measure. If we look at the location of the transmissiometers for the TDZ they're right at the RWY beginning and coupla hundreds feet apart so are the others. Does a reported RVR (derived from the automated device) of 125 M guaranties this value achievement along the whole TDZ? Surely NOT hence airbus recommendation NOT to discontinue takeoff in case visual reference is temporarily lost during LVO takeoff. RVR 125 equal 90 M VS is relevant for both takeoff and landing in terms of directional control during low speed regime with high power settings for takeoff and high speed rollout for LVO landing. Therefore I don't see any reason why RVR 125 can't be replaced by PIC as long as he sees 90 m from the flight deck. It appears all this misconception is predicated on the assumption that RVR is derived by automatic device thus being really accurate for the whole rwy portion along with the idea that the remaining 2 RVR values determine how the first one can or must be achieved. Relevant is the key word here. Well, not necessarily the case in the EU OPS land, can be human observation. So in the end what's safer PIC assessment of TDZ RVR of 125 M or human observation of RVR 125? Note this problem doesn't exist in FAA land coz RVR there can only be obtained by a automatic device and 2 RVR are required. Someone smarter than me out there can you please copy paste table air traffic management EU OPS AOM takeoff minima from the Jepp. Thanx.
125/150/150 - count 10 lights and fly (certified for 150 m ops only)
> first REPORTED value is REPLACED by pilot assesment, for 150m and more this is allowed
> first REPORTED value is REPLACED by pilot assesment, for 150m and more this is allowed
100/125/125 - no go (if certified for 125 m ops) > under specific additional rules for 125 m ops, RVR must be achieved but pilot replacement of reported RVR is no longer an option
xxx/125/125 - count 8 lights and fly (if certified for 125 m ops)
> required RVR is obtained in all parts as required by EU OPS
> required RVR is obtained in all parts as required by EU OPS
Summary: in all 3 cases pilot conducted the assessment of the initial RVR but for some reasons decided not to replace the reported value with his/her own in case 2. If 125 can be assessed and replace NO RVR reported it's logical that it can be assessed any time regardless of reported RVR. Finally reported RVR 125, below the minimum, was replaced by pilot assessment of RVR 150. Why can't you replace 100 with 125 if you see 8 CL? NO reported RVR or RVR reported below the minima is still a replacement regardless how you twist it. 125 M is a magic number here it seems. Why? It is indeed for EU OPS folks as they believe it provides reasonable assurance that the pilot having 90 VS with RVR 125M will have sufficient time to react and visual cues in both cases RTO and TO to keep the aircraft within the certification confinement 30 ft off the centerline by looking outside. RVR isn't panacea but a reasonable mitigation measure. If we look at the location of the transmissiometers for the TDZ they're right at the RWY beginning and coupla hundreds feet apart so are the others. Does a reported RVR (derived from the automated device) of 125 M guaranties this value achievement along the whole TDZ? Surely NOT hence airbus recommendation NOT to discontinue takeoff in case visual reference is temporarily lost during LVO takeoff. RVR 125 equal 90 M VS is relevant for both takeoff and landing in terms of directional control during low speed regime with high power settings for takeoff and high speed rollout for LVO landing. Therefore I don't see any reason why RVR 125 can't be replaced by PIC as long as he sees 90 m from the flight deck. It appears all this misconception is predicated on the assumption that RVR is derived by automatic device thus being really accurate for the whole rwy portion along with the idea that the remaining 2 RVR values determine how the first one can or must be achieved. Relevant is the key word here. Well, not necessarily the case in the EU OPS land, can be human observation. So in the end what's safer PIC assessment of TDZ RVR of 125 M or human observation of RVR 125? Note this problem doesn't exist in FAA land coz RVR there can only be obtained by a automatic device and 2 RVR are required. Someone smarter than me out there can you please copy paste table air traffic management EU OPS AOM takeoff minima from the Jepp. Thanx.
Last edited by 9.G; 14th Apr 2011 at 12:51.
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Refering to the EU-OPS 1 AOM taken from Jeppesen Text, Table 2 Take-off RVR/VIS clearly indicates with a note 2 (relevant to all facilities), that:
It can be replaced, so even when the RVR reported is 100/125/125 !?
Note 3 (only relevant to approved operators for lower than 150m = 125m/75m) is:
This note indicates that the discription below is extra. With other words the Note 2 as above still applies. !?
A part of the additional requirements is:
Does this mean that is needs to be a reported RVR, or can this 'RVR value' also be a pilot assessed value, to be achieved?
As far as I concern the 125 meters pilot assessment and the requirement for a visual segment of 90 meters are two different things Confusion has occured by wrong interpretation, of damn lawyer language
The reported RVR/VIS of the initial part of take-off run can be replaced by pilot assessment
Note 3 (only relevant to approved operators for lower than 150m = 125m/75m) is:
For additional information about Approved Operators refer to the description below this table.
A part of the additional requirements is:
The required RVR value has been achieved for all of the relevant RVR reporting points.
As far as I concern the 125 meters pilot assessment and the requirement for a visual segment of 90 meters are two different things Confusion has occured by wrong interpretation, of damn lawyer language
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Here's what FAA thinks about it:
8.6.2. RVR Availability and Use Requirements.
8.6.2.1. RVR Availability.
a. For Category II, RVR availability requirements for touchdown zone (TDZ), mid runway (MID), and ROLLOUT RVR (or a corresponding international equivalent location) should be provided for any runway over 8000 ft in length. TDZ and ROLLOUT RVR should be provided for runways less than 8000 ft. Exceptions to this requirement for U.S. Operators at international locations may be approved on a case by case basis by AFS-400, if an
equivalent level of safety can be established. Factors considered due to local circumstances at foreign airports may include minima requested, landing field length requested, characteristics of prevailing local weather conditions,
location of RVR sites or RVR calibration, availability of other supporting weather reports on nearby runways, etc.
b. Aircraft requiring a landing or takeoff distance in normal operation (using operational braking techniques) less than 4000 ft may be approved to use a single TDZ, MID, or ROLLOUT RVR report as applicable to the part of the runway used. For such operations, RVR values not used are optional and advisory, unless the aircraft operation
is planned to take place on the part of the runway where a MID or ROLLOUT RVR is located.
8.6.2.2. RVR Use. In general, the controlling RVR for Takeoff, Landing and Rollout are as follows:
a. Take-off:
(1) Where visibility minima are applicable, visibility must be reported sufficiently close to the takeoff runway to be considered valid or applicable. The determination of acceptability, if not otherwise addressed by FAA, may be determined by the operator or CHDO.
(2) Where RVR minima are applicable, RVR must be reported, and the RVR minimum value is considered to be controlling at each relevant RVR reporting point. The RVR/Visibility representative of the initial part of the take-off may be replaced by pilot assessment. For take-off operations the relevant RVR refers to any portion of the runway that is needed for takeoff roll, including that part of the runway that may be needed for a rejected take-off.
b. Landing.
(1) Where visibility minima are applicable, visibility must be reported sufficiently close to the landing runway to be considered valid or applicable. The determination of acceptability, if not otherwise addressed by FAA,
may be determined by the operator or CHDO. Where RVR is used, the controlling RVR for all Category I operations is the touchdown RVR. All other readings, if any, are advisory.
(2) The controlling RVR for Category II (for Category III see AC 120-28D) with or without rollout guidance control system is the TDZ RVR or equivalent. Mid and rollout RVR are advisory, unless otherwise specified in OpSpecs.
NOTE: An acceptable alternate set of OpSpecs specifying minimum values for MID and ROLLOUT RVRs may be provided for airplanes without a rollout guidance or control system. If determined appropriate by the FAA, and agreed to by the operator, TDZ, MID, and ROLLOUT may be specified as controlling. MID RVR, if relevant, may not be less than 400-ft. (125-meters). ROLLOUT RVR, if relevant, may not be less than 300-ft. (75-meters). For landing operations, the relevant RVR refers to the portion of the runway that is needed for landing down to a safe taxi speed (typically below 60-knots for large turbojet aircraft).
8.6.3. Pilot Assessment of Takeoff Visibility Equivalent to RVR. (See also 4.2. b and c). In special circumstances, provisions may be made for pilot assessment of takeoff visibility equivalent to RVR to determine compliance with takeoff minima. Provisions to authorize pilot assessed RVR is provided through Standard Operations Specifications. A pilot may assess visibility at the take off position in lieu of reported TDZ RVR (or equivalent) IAW the requirements detailed below:
a. TDZ RVR is inoperative, or is not reported (e.g., TDZ RVR inoperative, ATS facility is closed); or
b. Local visibility conditions as determined by the pilot indicate that a significantly different visibility exists than the reported RVR (e.g., patchy fog, blowing snow, RVR believed to be inoperative or inaccurate); and
c. Pertinent markings, lighting, and electronic aids are clearly visible and in service (e.g., no obscuring clutter); and
d. The assessment is made using an accepted method regarding identification of an appropriate number of centerline lights, or markings, of known spacing visible to the pilot when viewed from the flight deck when the
aircraft is at the take-off point; and
e. Pilot assessment of visibility as a substitute for TDZ (takeoff) RVR is approved for the operator, and observed visibility is determined to be greater than the equivalent of 300 RVR (90m); and
f. A suitable report of the pilot’s determination of visibility is forwarded to ATS or to the operator, as applicable (e.g., if an ATS facility is available and providing ATS services, or if the operator elects to receive such reports).
NOTE: A suitable report of a pilot’s determination of visibility provided to ATS or to the operator is intended to facilitate other operations and timely distribution of meteorological information. It is not intended to be a verification of minima or limit or restrict minima for the aircraft making the report.
Why don't we forget all the confusion for a sec and look at the whole ops from the simple pilot's pilots point of view? The operation must be SAFE that's the goal. How can it be achieved? There's no safer means for a manual flight but to have a adequate visual contact with the surroundings ergo see where you gonna roll, fly. That's the reason a minima was invented. At some point (DA, MDA DH whaever) a pilot must identify the environment by visual means to assess the whole situation and to decide what's next. Despite all the fancy technic and installation blah blah blah the pilot plays the pivot role in that decision making hence the option to continue the approach regardless of RVR down to the minima. Nothing else happens with LVTO but instead of DH there's a beginning of takeoff roll position. Same procedure here: look outside and deicide. RVR transmissiomenters don't do anything else but to assess the visibile segment at the very same point. Conversely RVR 200 is reported but upon lineup I only see 5 CL, certainly will I not take off regardless of what the fancy machine reports. To prevent arbitrary decision making regarding how many CL will one need 90 m visual segment was imposed which proved to be adequate to ensure directional control. It's totally natural for the pilot to assess the visual cues and the law maker made a provision for that.
8.6.2. RVR Availability and Use Requirements.
8.6.2.1. RVR Availability.
a. For Category II, RVR availability requirements for touchdown zone (TDZ), mid runway (MID), and ROLLOUT RVR (or a corresponding international equivalent location) should be provided for any runway over 8000 ft in length. TDZ and ROLLOUT RVR should be provided for runways less than 8000 ft. Exceptions to this requirement for U.S. Operators at international locations may be approved on a case by case basis by AFS-400, if an
equivalent level of safety can be established. Factors considered due to local circumstances at foreign airports may include minima requested, landing field length requested, characteristics of prevailing local weather conditions,
location of RVR sites or RVR calibration, availability of other supporting weather reports on nearby runways, etc.
b. Aircraft requiring a landing or takeoff distance in normal operation (using operational braking techniques) less than 4000 ft may be approved to use a single TDZ, MID, or ROLLOUT RVR report as applicable to the part of the runway used. For such operations, RVR values not used are optional and advisory, unless the aircraft operation
is planned to take place on the part of the runway where a MID or ROLLOUT RVR is located.
8.6.2.2. RVR Use. In general, the controlling RVR for Takeoff, Landing and Rollout are as follows:
a. Take-off:
(1) Where visibility minima are applicable, visibility must be reported sufficiently close to the takeoff runway to be considered valid or applicable. The determination of acceptability, if not otherwise addressed by FAA, may be determined by the operator or CHDO.
(2) Where RVR minima are applicable, RVR must be reported, and the RVR minimum value is considered to be controlling at each relevant RVR reporting point. The RVR/Visibility representative of the initial part of the take-off may be replaced by pilot assessment. For take-off operations the relevant RVR refers to any portion of the runway that is needed for takeoff roll, including that part of the runway that may be needed for a rejected take-off.
b. Landing.
(1) Where visibility minima are applicable, visibility must be reported sufficiently close to the landing runway to be considered valid or applicable. The determination of acceptability, if not otherwise addressed by FAA,
may be determined by the operator or CHDO. Where RVR is used, the controlling RVR for all Category I operations is the touchdown RVR. All other readings, if any, are advisory.
(2) The controlling RVR for Category II (for Category III see AC 120-28D) with or without rollout guidance control system is the TDZ RVR or equivalent. Mid and rollout RVR are advisory, unless otherwise specified in OpSpecs.
NOTE: An acceptable alternate set of OpSpecs specifying minimum values for MID and ROLLOUT RVRs may be provided for airplanes without a rollout guidance or control system. If determined appropriate by the FAA, and agreed to by the operator, TDZ, MID, and ROLLOUT may be specified as controlling. MID RVR, if relevant, may not be less than 400-ft. (125-meters). ROLLOUT RVR, if relevant, may not be less than 300-ft. (75-meters). For landing operations, the relevant RVR refers to the portion of the runway that is needed for landing down to a safe taxi speed (typically below 60-knots for large turbojet aircraft).
8.6.3. Pilot Assessment of Takeoff Visibility Equivalent to RVR. (See also 4.2. b and c). In special circumstances, provisions may be made for pilot assessment of takeoff visibility equivalent to RVR to determine compliance with takeoff minima. Provisions to authorize pilot assessed RVR is provided through Standard Operations Specifications. A pilot may assess visibility at the take off position in lieu of reported TDZ RVR (or equivalent) IAW the requirements detailed below:
a. TDZ RVR is inoperative, or is not reported (e.g., TDZ RVR inoperative, ATS facility is closed); or
b. Local visibility conditions as determined by the pilot indicate that a significantly different visibility exists than the reported RVR (e.g., patchy fog, blowing snow, RVR believed to be inoperative or inaccurate); and
c. Pertinent markings, lighting, and electronic aids are clearly visible and in service (e.g., no obscuring clutter); and
d. The assessment is made using an accepted method regarding identification of an appropriate number of centerline lights, or markings, of known spacing visible to the pilot when viewed from the flight deck when the
aircraft is at the take-off point; and
e. Pilot assessment of visibility as a substitute for TDZ (takeoff) RVR is approved for the operator, and observed visibility is determined to be greater than the equivalent of 300 RVR (90m); and
f. A suitable report of the pilot’s determination of visibility is forwarded to ATS or to the operator, as applicable (e.g., if an ATS facility is available and providing ATS services, or if the operator elects to receive such reports).
NOTE: A suitable report of a pilot’s determination of visibility provided to ATS or to the operator is intended to facilitate other operations and timely distribution of meteorological information. It is not intended to be a verification of minima or limit or restrict minima for the aircraft making the report.
Why don't we forget all the confusion for a sec and look at the whole ops from the simple pilot's pilots point of view? The operation must be SAFE that's the goal. How can it be achieved? There's no safer means for a manual flight but to have a adequate visual contact with the surroundings ergo see where you gonna roll, fly. That's the reason a minima was invented. At some point (DA, MDA DH whaever) a pilot must identify the environment by visual means to assess the whole situation and to decide what's next. Despite all the fancy technic and installation blah blah blah the pilot plays the pivot role in that decision making hence the option to continue the approach regardless of RVR down to the minima. Nothing else happens with LVTO but instead of DH there's a beginning of takeoff roll position. Same procedure here: look outside and deicide. RVR transmissiomenters don't do anything else but to assess the visibile segment at the very same point. Conversely RVR 200 is reported but upon lineup I only see 5 CL, certainly will I not take off regardless of what the fancy machine reports. To prevent arbitrary decision making regarding how many CL will one need 90 m visual segment was imposed which proved to be adequate to ensure directional control. It's totally natural for the pilot to assess the visual cues and the law maker made a provision for that.
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The two confusing statements are " required RVR value has been achieved for all of the relevant RVR repoting points" and " RVR/VIS of the initial part of the take-off run can be replaced by pilot assessment."
Does this mean that the second statement supersedes the first?
If we're talking "english language", saying something replaces means it is no longer needed. So do you still need all reporting points to be 125m or more? Or is it only applicable if TDZ RVR is inop which then allows you to replace the initial run by pilot assessment?
Does this mean that the second statement supersedes the first?
If we're talking "english language", saying something replaces means it is no longer needed. So do you still need all reporting points to be 125m or more? Or is it only applicable if TDZ RVR is inop which then allows you to replace the initial run by pilot assessment?
Last edited by cochise; 16th Apr 2011 at 11:10. Reason: sp
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cochise, regarding the replacement read the previous post I couldn't have put any better. simply put, 90 meters outta cockpit window equates to 125 M RVR for all airbus models therefore whether you see 90 m or RVR 125 is reported is the same. Conclusion TDZ RVR replacement by pilot's observation is allowed regardless of NO report or reported below, above or whatever.
Relevant is what it is: closely connected or pertinent to the matter from the dictionary. In practical terms: if you skip the first 1/3 of the rwy and make intersection takeoff TDZ is irrelevant, isn't it? If you calculate the performance within 2/3 or the TODA, the last 1/3 is irrelevant, isn't it? If the rwy has got 4 RVR readings and over 4000 m long do you care bout the 4th RVR reading? No, hence irrelevant. Apropos it's valid for landing as well. Let's say a very long runway with only ILS CAT 1 approach from one end reports RVR of 100/100 M due to thick fog. You can clearly see the other half of the RWY from the flight deck due to local WX phenomena. Is RVR 100/100 relevant and if so for what? Well, it is for the ILS from one side but completely irrelevant from the other coz it's possible to shoot a visual.
Relevant is what it is: closely connected or pertinent to the matter from the dictionary. In practical terms: if you skip the first 1/3 of the rwy and make intersection takeoff TDZ is irrelevant, isn't it? If you calculate the performance within 2/3 or the TODA, the last 1/3 is irrelevant, isn't it? If the rwy has got 4 RVR readings and over 4000 m long do you care bout the 4th RVR reading? No, hence irrelevant. Apropos it's valid for landing as well. Let's say a very long runway with only ILS CAT 1 approach from one end reports RVR of 100/100 M due to thick fog. You can clearly see the other half of the RWY from the flight deck due to local WX phenomena. Is RVR 100/100 relevant and if so for what? Well, it is for the ILS from one side but completely irrelevant from the other coz it's possible to shoot a visual.
Only half a speed-brake
This becomes repetitive.
Here's the full sentence (my bolding):
The reported RVR/visibility value representative of the initial part of the take-off run can be replaced by pilot assessment.
First of all, this waiver is not included with the specific conditions under which you can reduce RVR below 150 m. No replacing a reported value for 125m ops is allowed > 80/125/125 is no go.
Second, it allows an operator to replace a reported value. I.e. if the readout would be missing > the xxx/150/150 situation is not solved through this note, but through other paragraphs.
Third, for 125/125/125 a 90 m visual segment is required, airbus geometry provides, so far so good. But for xxx/125/125, a visual segment 90 m only translates to 112,5/125/125 > the "RVR achieved" condition is not met by such pilot observation.
Pilot RVR assesment is one thing, replacement of reported RVR/VIS value another. I do believe that a non-LVO operator could take off with 350/1800/800 if pilot sees down the runway, replacing the reported value of initial part of TOR. I do believe that 100/125/125 cannot be replaced once reported.
Sincerely,
FD (the un-real)
Here's the full sentence (my bolding):
The reported RVR/visibility value representative of the initial part of the take-off run can be replaced by pilot assessment.
First of all, this waiver is not included with the specific conditions under which you can reduce RVR below 150 m. No replacing a reported value for 125m ops is allowed > 80/125/125 is no go.
Second, it allows an operator to replace a reported value. I.e. if the readout would be missing > the xxx/150/150 situation is not solved through this note, but through other paragraphs.
Third, for 125/125/125 a 90 m visual segment is required, airbus geometry provides, so far so good. But for xxx/125/125, a visual segment 90 m only translates to 112,5/125/125 > the "RVR achieved" condition is not met by such pilot observation.
Pilot RVR assesment is one thing, replacement of reported RVR/VIS value another. I do believe that a non-LVO operator could take off with 350/1800/800 if pilot sees down the runway, replacing the reported value of initial part of TOR. I do believe that 100/125/125 cannot be replaced once reported.
Sincerely,
FD (the un-real)
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F.D. I don't see any point in arguing bout someone's believes. Logic is absolute. It's your choice but something worthwhile to know bout RVR MEASUREMENT REPORTS:
ICAO recommends that RVR reports are given with 50m increments when the RVR is less than 800m and 25m increments when the RVR is less 150m. In any case, any change of the RVR value must be known by the ATC as soon as possible and in less than 15 seconds. Consequently next step below 150 would be 125, 100, 75, 50. 90 is a minimum operational value corresponding to 125 measuring value purely due to technicalities.
ICAO recommends that RVR reports are given with 50m increments when the RVR is less than 800m and 25m increments when the RVR is less 150m. In any case, any change of the RVR value must be known by the ATC as soon as possible and in less than 15 seconds. Consequently next step below 150 would be 125, 100, 75, 50. 90 is a minimum operational value corresponding to 125 measuring value purely due to technicalities.
Only half a speed-brake
Poor choice of words on my side, beliefs aside, logic counts I agree.
No gripe here.
9.G that's a belief. 90 m segment from an Airbus does not satisfy 125m RVR. 100 perhaps, but not the 125 m requirement. Better yet, what about ATR?
Consequently next step below 150 would be 125, 100, 75, ...
...
...
... 90 is a minimum operational value corresponding to 125 measuring value purely due to technicalities.
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F.D. it's not about what was at the beginning the egg or the chicken but about what's the foundation? Once again the key figure is 90 M. That's the required visual segment throughout the takeoff roll proven to provide adequate directional control with external reference. All airbus models geometrically are above that value when it comes to the visual segment outta cockpit. The regulator has decided that 125 is lowest figure without PVI or HUD. Consequence is that RVR 125 merely satisfies 90 m visual segment requirement. Now, I need 90 M VS throughout the takeoff roll to control the aircraft. How can I be sure to achieve that? Can I line up and taxi down the runway to see if I can see 6 CL constantly? Well, I could but what are the odds it remains the same by the time I come back to takeoff position and how much delay will it cause? Is it gonna remain the same? All very much depends on local weather phenomena, doesn't it? Therefore I need a machine or human observer reporting RVR along the TODA. You, sitting in the cockpit or the human observer or transmissiometer at the takeoff position are looking at the same portion of the runway, no difference there. Moreover 125 RVR measurement in TDZ on 4000 M RWY does not guaranty the achievement of such over the whole TDZ. It's a reasonable assurance of what you might expect. Is 90 M VS the same as 125 RVR in geometrical terms, NO. Can I replace RVR measurement at the takeoff position with 90 M VS, YES coz that's all I need to perform LVTO with external references. 90 m VS and RVR 125 M aren't the same in geometrical terms but both have the same function namely safe takeoff. FAA approach is clearly allowing that. It's safe and sound.
