Contaminated

[Topper80]

What's your company policy about CAT II / III on contaminated rwy ?

[bigduke6]

It makes no difference, the same braking action limits apply for all visibility categories, even VMC approach.

[No_Speed_Restriction]

If I'm not mistaken, I think he means autoland requirements/penalties (if any).

[aristoclis]

Autoland has been demonstrated in dry and wet runways (A320). Manual landing is allowed in CATII minima or better.

[9.G]

Automatic rollout performance has been approved on dry and wet runways, but performance on snow-covered or icy runways has not been demonstrated.

Autoland can be performed on contaminated RWY however airbus recommendation is to disconnect the A/P after touch down to perform manual rollout as the auto rollout isn't warranted on contaminated RWY. Cross wind limitations for manual landing or rollout on contaminated RWY do apply :ok:

[aristoclis]

9.G

You are absoloutely right.:ok:

Manual rollout is correct. Minima RVR 125m for our company.

[TruthHurts]

Agreed with the AutoLand but not Auto rollout as the contamination levels are usually not even on the runway surface thus the autopilot can not steer the aircraft within the acceptable limits.

So the limit should be CAT 3A as the aircraft has only the autoland but no auto rollout, and the min RVR TDZ (200M), MID and RO should be 125M if centerline lights are 15M or less, but if the CL lights are 30M then the Min RVR for MID and RO should be 150M.

[9.G]

TruthHurts, CAT III doesn't preclude a manual landing from DH of 50 FT therefore the requirement of TDZ RVR 200 M to complete an autoland NO RVR is needed at all. Thus here we're facing somewhat a grey zone once again.
CAT III a is a conservative approach and certainly not wrong but all you need is RVR 125 to perform manual rollout therefore RVR 125/125/125 may be sufficient. :ok:

[TruthHurts]

Yes we can do a manual Landing only in failure case, can not be planned.

Regarding the Manual Roll Out it is always judged as the Min T/O RVR, that why is you have 15M CL then you can do the 125M but if it is 30M then it is 150M.

In my view the RVR 125M or 150M are ok in the SIM with Cat3A wether conditions.

[aristoclis]

Although I must admit I am confused myself, the way I understand it is this:

CATIIIa is not an issue (regarding RVR minima) in contaminated since you will perform an autoland, you disengage APs at touch and perform a manual rollout (mid and stop RVR 125m or above). CATIIIa minima of 50ft-200m are above RVR required for manual rollout (125m) anyway and iaw OPS1 rollout control/guidance system is not required for CATIIIa.

The grey zone starts with CATIIIb with minima 50ft-150m or minDH-125m. In theory you could also disengage APs at touch (mid and stop complying) but according to OPS1 for these cases you must have at least fail-passive rollout control/guidance system.

[safetypee]

I would be surprised if any national authority in Europe would authorise autolanding on contaminated runways.
Most aircraft require different landing distance data sets when autolanding; see archives. (www.pprune.org/archive/index.php/t-304333.html)
Does any operator have data for auto-contaminated landings?
IIRC some certifications mandate anti-skid or require autobrake for autoland.

Manual landing data is based on the standard factors which provide a landing distance safety margin. However, in Europe, the contaminated landing distance is not necessarily obtained from the same ‘factored’ process (CS AMC 25.1591); the safety margins are greatly reduced and operators are advised to avoid contaminated conditions. Also, the distances provided may be based on thrust reverse use. This might add additional risk to the operation if reverse is not considered in normal wet/dry calculations due to its 'reliability' (the norm for most aircraft).

See ‘Autoland on Contaminated Runways’. (www.smartcockpit.com/flightops) This covers most flying aspects but not those of landing distance; note that the EASA contaminated distance requirements were published after this document.
A notable quote “… a human pilot has to adapt his technique for landing on a contaminated runway, but an autopilot cannot.
Re this, see:- NYC01IA068 (http://www.ntsb.gov/ntsb/brief2.asp?ev_id=20010212X00438&ntsbno=NYC01IA068&akey=1)

[9.G]

safetypee, I strongly recommend to pay a visit to your QRH, airbus does provide ALD for AUTOLAND on contaminated RWY in the inflight performance section. :ok:

[safetypee]

Thanks for the info 9.G, I’m not familiar with Airbus operations.
However, I would ask if there is any additional guidance in the QRH as to how the ALD (contaminated autoland performance) should be used. As in the accident report above, although not specifically prohibited, the operation had not been evaluated (A320 Jan 2001).
Is there any caution about reduced safety margins; is the data for use in normal pre-planned operations, or only as advice to be used where judged necessary?
Does the AFM show any certificated data for autoland on contaminated runways, if not, does your national authority allow normal operations based on advisory data?

[9.G]

safetypee, airbus came up with autoland on contaminated runway coupla years ago, don't remember exactly when. There's no specific technique described in the Manuals of how to conduct an autoland on contaminated runways. However there's wind limitation on contaminated RWY as directional control, not the autoland itself, is the most critical issue here. It's all legitimate and anchored by the lawmaker. EU OPS does have a provision about landing on contaminated runway without specifying the landing technique obliging the operator at the same time to take all the aspects of operation into account. The table gives ou the AUTOLAND on contaminated RWY for FALPS 3 and FULL and Auto Brake LOW & MED based on type of contaminant not the breaking action. This figures are certified by authorities. AFM certifies the autoland on contaminated RWY using the appropriate software or tables. The problem is that those tables are drown based on fully functional aircraft. Next question is what if you have, let's say one brake deactivated? Here we have a combination of 3 factors: LVO, contaminated RWY performance, provision for malfunctions.

The solution is EFB from the airbus giving you the option of calculating actual landing performance for given conditions taken into account aircraft technical status, landing technique and level of contamination. :ok:

[safetypee]

9.G, thanks for the expanded clarification; very interesting.
I cannot locate any EU–OPS reference to auto landing on contaminated runway’; have you a para number?

Overall, autolanding on contaminated runways appears to have a higher risk and might contravene certification regulations – i.e. it falls into a gap between operational and aircraft certification requirements.
E.g. CS–AWO 142 ‘Landing distance’, requires that “The landing distance required must be established and scheduled in the aeroplane Flight Manual if it exceeds the distance scheduled for manual landing”. This accounts for any difference in autoland performance.
CS–AWO 342 ‘Landing distance’, deals with system and procedural aspects; “If there is any feature of the system or the associated procedures which would result in an increase to the landing distance required, the appropriate increment must be established and scheduled in the aeroplane Flight Manual.” This considers increased approach speeds, nose lowering, spoiler selection, etc.
CS-AWO 101 ‘Safety level’ outlines the overall safety level, “The safety level in automatic landing may not be less than that achieved in manual landing. Hence, in showing compliance with the performance and failure requirements, the probabilities of performance or failure effects may not be factored by the proportion of landings made under automatic control.”
The last sentence is important when comparing auto and manual landings on contaminated runways. For ‘contaminated’ manual landings, the increased risk due to reduced safety margin and accuracy of reporting runway braking action can be offset by the reduced frequency of encounter and the advice to avoid such conditions, for autoland it has to be ‘safe’ at all times.

Thus unless a manufacturer specifically approves the operation in the AFM, including approved landing distances, then the use of the advisory data, if accepted by the National Authority, places all responsibility for managing the risks the operation on the operator (which usually is passed down to the Captain).
The operator has to judge the risk, and as asked in the initial question, part of this risk mitigation is to provide guidance for crews.

In Cat 2, both the approach and landing can be flown manually and thus the manual-landing contaminated data could be used within the basic EU-OPS requirements. However, in Europe a manual Cat 2 approach requires specific certification (very few aircraft have this – cost - it’s not the same as auto approach). A manual landing from a Cat 2 auto approach should be OK providing that the autos remain coupled to 80% of DH (CS AWO 233).
In Cat 3, an auto approach and landing cannot be terminated by a manual landing by choice, only due to a system failure. Thus in any contaminated Cat 3 operation, all CS AWO requirements must be met, which suggests the need for specific, highly reliable landing-distance data.
Even if a manufacturer has provided ‘good’ data, in use it is subject to inaccuracies in measuring the type of contaminant and depth (estimating braking action), and thus the operation is unlikely to meet the AWO requirements.
Hence the suggestion above that the operational approval, is at best, only advisory.

So, re #1 (Topper80);-
Avoid landing on contaminated runways if possible; be aware of the reduced landing-distance safety-margins, fly accurate speeds and flare profiles – if in doubt go-around, restrict the crosswind component to 10 kts, preferably 5 kts with autos, use auto brake as recommended (IMHO max manual brake is best), and use max reverse thrust (as advised).
If your operator does not provide this type of advice, remember who holds the responsibility for managing risk in the operation – choose the safest course of action.

CS_AWO (www.easa.eu.int/ws_prod/g/doc/Agency_Mesures/Certification_Spec/decision_ED_2003_06_RM.pdf)

[9.G]

Landing - Wet and contaminated runways (EU-OPS 1.520)

(a) When the appropriate weather reports or forecasts, or a combination thereof, indicate that the runway at the estimated time of arrival may be wet (Definitions), the landing distance available shall be at least 115% of the required landing distance on dry runway as determined above.

(b) When the appropriate weather reports or forecasts, or a combination thereof, indicate that the runway at the estimated time of arrival may be contaminated (Definitions), the landing distance available shall be at least the landing distance determined in accordance with sub-paragraph (a) above, or at least 115% of the landing distance determined in accordance with approved contaminated landing distance data or equivalent, accepted by the Authority, whichever is greater.

(c) A landing distance on a wet runway shorter than that required by sub-paragraph (a) above, but not less than that required for landing on dry runway, may be used if the Aircraft Flight Manual includes specific additional information about landing distances on wet runways.

(d) A landing distance on a specially prepared contaminated runway shorter than that required by sub-paragraph (b) above, but not less than that required for landing on dry runway, may be used if the Aircraft Flight Manual includes specific additional information about landing distances on contaminated runways.

(e) When showing compliance with sub-paragraphs (b), (c) and (d) above, the criteria for landing on dry runway shall be applied accordingly except that the 60% margin shall not be applied to sub-paragraph (b) above.

Note: the governing para doesn't specify the landing technique but prescribes to account for detrimental factors. It's up to the operator to cater for it. The lawmaker doesn't care about the landing technique as long as the regulatory performance requirements are met. Obviously AUTO LAND requires longer distance than a manual one on contaminated RWY however if the LD available is sufficient, no reason not to do it. Very important aspect here is the fact that the approval is based on the contaminant type not the reported BA or FC.

AUTOLAND ALD on contaminated RWY is part of AFM and is approved by EASA. :ok:

[9.G]

airbus brochure in flight landing performance assessment is a document intended for improved understanding and interim implementation of the new TALPA concept for operators. :ok:

[grounded27]

This is an often mis understood subject, any moving object within a specified area around the runway will cause a contaminated runway. Often an autoland gripe for landing lt or rt of centerline is caused by a contaminated runway not just rollout. The only way to ensure you have a clean ILS is to verify with the tower that the runway is not contaminated, this is rarely done.

THIS IS WHAT CONTAMINATED MEANS IN REFERENCE TO CATIII APPROACHES.