CATIII operations. Go around below DH.
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CATIII operations. Go around below DH.
Hello everybody.
I'm an avionics test engineer on Antonov Design Bureau.
We've just completed the flight tests of CAT3A capability on our new regional jet An-148. It's our first CAT3 certification. Now we on the final stage of certification progress.
The question is:
"What is mandatory or the best way to do in case of autoland WARNING below decision height (DH = 50 ft)? We still have strong discussion of the subject with our test pilots. My opininon is GO AROUND, because CATIII operations require AUTOLAND. My colleagues state they can make manual landing after loss of autoland"
Thanks for your cooperation.
I'm an avionics test engineer on Antonov Design Bureau.
We've just completed the flight tests of CAT3A capability on our new regional jet An-148. It's our first CAT3 certification. Now we on the final stage of certification progress.
The question is:
"What is mandatory or the best way to do in case of autoland WARNING below decision height (DH = 50 ft)? We still have strong discussion of the subject with our test pilots. My opininon is GO AROUND, because CATIII operations require AUTOLAND. My colleagues state they can make manual landing after loss of autoland"
Thanks for your cooperation.
Only half a speed-brake
AF: Your question is far too technical for an open forum like this - it may yield answers not professional enough. The design team should look for certification specifications in appropriate documents such as FAR part 25 or/and EASA CS-25 ... which I am sure they do.
My last type specific LVO training was done by an ex-SAS examiner inhouse at Toulouse Airbus training center on a CAT IIIB aircraft. The advised course of action for autoland problem below minima was to DECIDE. If the real situation provides enough visual cues, it is entirely possible for the captain to land; and it is legal. If the captain does not see (s)he will go around and everybody understands that the gear will touch down during the manoeuvre. Both options are available. The key point is the term enough visual cues.
Take care,
FD (the un-real)
PS: As I proposed, my contribution may yield answers not professional enough.
My last type specific LVO training was done by an ex-SAS examiner inhouse at Toulouse Airbus training center on a CAT IIIB aircraft. The advised course of action for autoland problem below minima was to DECIDE. If the real situation provides enough visual cues, it is entirely possible for the captain to land; and it is legal. If the captain does not see (s)he will go around and everybody understands that the gear will touch down during the manoeuvre. Both options are available. The key point is the term enough visual cues.
Take care,
FD (the un-real)
PS: As I proposed, my contribution may yield answers not professional enough.
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Thanks a lot for you answer. What we have, that's only requirements, definitions and yours (I mean - world wide) professional experience. As ICAO docs state:
"Cat I and II ILS procedures differ from those of Cat IIIa in one important
respect. They require that the crew visually spot the approach lights — and, eventually, other runway environment cues — in order to safely continue to a
respect. They require that the crew visually spot the approach lights — and, eventually, other runway environment cues — in order to safely continue to a
landing by visual reference alone. In other words, the landing pilot must be able to properly judge the flare point, make the landing, and execute the rollout visually.
Cat IIIa approaches, on the other hand, merely require that the pilot establish sufficient visual reference with the touchdown zone lights to
ensure that landing is occurring in the touchdown zone. The pilot may never even see the approach lights. Visual reference may be such that the pilot is unable to properly judge the flare point or manually control the aircraft during the initial rollout. The autopilot will normally execute the flare, landing, and rollout down to taxi speed."
Of course, I mean the only CATIIIA real visual conditions. It's clear, if you land in good weather you can make the decision - to land or to go around.
Of course, I mean the only CATIIIA real visual conditions. It's clear, if you land in good weather you can make the decision - to land or to go around.
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A_F - if the 'autoland warning' means the a/c is unable to complete an A/P landing, then in all the operators I have been with (737 all types) it is a mandatory g/a. The danger is that although there may be some visual clues at failure, they can rapidly disappear meaning that the flare and t/down could be endangered. I guess that if, in the unlikely event that it is CatIII for cloudbase and not visibility, you 'broke cloud' at 50'(/DH) and saw the whole runway you might be justified in going against the QRH (g/a) but I suspect there will a 'chat' in your manager's office!
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CATIII a or B
all post about CATII IIIa Cat IIIB have a good explain and is legal to land by manual landing with visual cues (some depend of the company policy)but don't forget about if Visibility became below minima announce by ATC and any approach that you intend to land even if you have visual cues (autoland and manual land) landing is Ilegal.
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• CAT III Operations
In CAT III operations with DH, the condition required at DH is that there should be visual references which confirm that the aircraft is over the touchdown zone. Go-around is mandatory if the visual references do not confirm this.
(Appendix 1 to EU-OPS 1.430)
- For Category IIIA operations, and for Category IIIB operations with failpassive flight control systems, a pilot may not continue an approach below the decision height unless a visual reference containing a segment of at least 3 consecutive lights being the centerline of the approach lights, or touchdown zone lights, or runway centerline lights, or runway edge lights, or a combination of these is attained and can be maintained.
You can land A.F. but it's a tough call.
In CAT III operations with DH, the condition required at DH is that there should be visual references which confirm that the aircraft is over the touchdown zone. Go-around is mandatory if the visual references do not confirm this.
(Appendix 1 to EU-OPS 1.430)
- For Category IIIA operations, and for Category IIIB operations with failpassive flight control systems, a pilot may not continue an approach below the decision height unless a visual reference containing a segment of at least 3 consecutive lights being the centerline of the approach lights, or touchdown zone lights, or runway centerline lights, or runway edge lights, or a combination of these is attained and can be maintained.
You can land A.F. but it's a tough call.
Assuming that the design – certification standard of the autoflight system meets the requirements in CS AWO 300 and CS25 (AC 29 / FAR25), then the operating requirements (EU-OPS, FAR121) generally determine both the minimum RVR and the land/GA options for the crew.
Cat 3A does not necessarily require autoland; see CS-AWO 321.
For 50 ft DH (Cat3A) in RVRs greater than 200m (may vary by aircraft type), where the crew have and can maintain the required visual references and the aircraft is on a stable flight path, etc, etc, then the crew can continue to land.
However, a manufacturer/regulator can impose an operating limit requiring a GA if the aircraft handling / workload / flight deck view / system characteristics etc for continued landing warrants it.
One difference to the above, particularly in Europe, is if the aircraft/autoflight system is certificated as ‘highly reliable fail passive’ enabling reduced RVR operations ~ 150m, then a mandatory GA would probably be required.
EASA Certification Specifications Agency Measures | Certification specifications
Cat 3A does not necessarily require autoland; see CS-AWO 321.
For 50 ft DH (Cat3A) in RVRs greater than 200m (may vary by aircraft type), where the crew have and can maintain the required visual references and the aircraft is on a stable flight path, etc, etc, then the crew can continue to land.
However, a manufacturer/regulator can impose an operating limit requiring a GA if the aircraft handling / workload / flight deck view / system characteristics etc for continued landing warrants it.
One difference to the above, particularly in Europe, is if the aircraft/autoflight system is certificated as ‘highly reliable fail passive’ enabling reduced RVR operations ~ 150m, then a mandatory GA would probably be required.
EASA Certification Specifications Agency Measures | Certification specifications
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Would be interesting to know if you can continue manually in HUD manual CAT III approved 737s in case of an autopilot failure.
In fail operational ones you have to check if above or below 200ft RA, the system and failure logic changes at alert height. For example the NO AUTOLAND message is inhibited, same as NO LAND 3 or LAND 2, and autoland is assured below 200ft, above 200ft it's a mandatory go-around.
In fail passive ones it is a mandatory go-around for all failures except AT disengagement, manual thrust operation is allowed in that case. However the relevant table has a note that manual landings are permitted "If suitable visual reference is established", however it fails to define what a suitable visual reference is.
However it further states for fail passive operation:
Autopilot failures are not considered for fail operational planes below 200ft as the system should be able to cope with all failures at that point, besides there is no DH anymore.
In fail operational ones you have to check if above or below 200ft RA, the system and failure logic changes at alert height. For example the NO AUTOLAND message is inhibited, same as NO LAND 3 or LAND 2, and autoland is assured below 200ft, above 200ft it's a mandatory go-around.
In fail passive ones it is a mandatory go-around for all failures except AT disengagement, manual thrust operation is allowed in that case. However the relevant table has a note that manual landings are permitted "If suitable visual reference is established", however it fails to define what a suitable visual reference is.
However it further states for fail passive operation:
• For operations to actual RVR values less than 300m, a go-around is assumed in the event of an autopilot failure at or below DH. This means that a go-around is the normal action.
• There may be circumstances where the safest action is to continue the landing. Such circumstances include the height at which the failure occurs, the actual Visual references, and other malfunctions. This would typically apply to the late stages of the flare.
• It is not forbidden to continue the approach and complete the landing when the Commander or the pilot to whom the conduct of the flight has been delegated, determines that this is the safest course of action.
• There may be circumstances where the safest action is to continue the landing. Such circumstances include the height at which the failure occurs, the actual Visual references, and other malfunctions. This would typically apply to the late stages of the flare.
• It is not forbidden to continue the approach and complete the landing when the Commander or the pilot to whom the conduct of the flight has been delegated, determines that this is the safest course of action.
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The visual cues requirements at DH in CAT III are meant for normal operation, I assume.
The thing is that below CAT II minima it is considered that there are not enough visual references to make a safe flare and landing, as you point out.
If there is an autoland warning, the airplane will not land, nor do an automatic roll out, so if it occurs below DH (with the required visual cues, of course, otherwise we would be going around already) it is captain's decision. If he assesses that he can flare, touch down and roll out with the available visual references he can land. This can only happen (in my opinion) if the actual visibility is higher than expected
Probably the most sensible thing to do is to go around expecting a bounce on the runway unless the he can clearly see that a landing is safe.
Besides, in a such an approach after a long haul flight, jet lag, fatigue, etc... our ability to correctly perceive the runway with just a few lights in the fog can be impaired. If the warning is due to a deviation from LOC or G/S during a landing with crosswind, Can we really see how the runway is with respect to the airplane with just three or four lights in sight, correct the flight path and land?
The thing is that below CAT II minima it is considered that there are not enough visual references to make a safe flare and landing, as you point out.
If there is an autoland warning, the airplane will not land, nor do an automatic roll out, so if it occurs below DH (with the required visual cues, of course, otherwise we would be going around already) it is captain's decision. If he assesses that he can flare, touch down and roll out with the available visual references he can land. This can only happen (in my opinion) if the actual visibility is higher than expected
Probably the most sensible thing to do is to go around expecting a bounce on the runway unless the he can clearly see that a landing is safe.
Besides, in a such an approach after a long haul flight, jet lag, fatigue, etc... our ability to correctly perceive the runway with just a few lights in the fog can be impaired. If the warning is due to a deviation from LOC or G/S during a landing with crosswind, Can we really see how the runway is with respect to the airplane with just three or four lights in sight, correct the flight path and land?
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If there is an autoland warning, the airplane will not land, nor do an automatic roll out, so if it occurs below DH (with the required visual cues, of course, otherwise we would be going around already) it is captain's decision
The airplane will autoland...just not as smoothly as you might expect under normal circumstances.
TriStar...in a class of its own...and very very good, even under adverse circumstances.
I kid you not.
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Thanks to all for professional answers.
Yes, as was pointed out, CS-AWO 321 really stands, that you can land without autoland. But in that case you have to demonstrate enough manual landings in visual conditions, that (believe me) is real challenge for certification without HUD.
And the last question.
What about flight manuals? In the most of them only one recomendation is in real visual conditions:
Boeing 777:
A330:
Any of professional pilots of this forum, who caught LAND warning in real life, follow the instructions without thought, or try to assess the situation and land manually?
Yes, as was pointed out, CS-AWO 321 really stands, that you can land without autoland. But in that case you have to demonstrate enough manual landings in visual conditions, that (believe me) is real challenge for certification without HUD.
And the last question.
What about flight manuals? In the most of them only one recomendation is in real visual conditions:
Boeing 777:
"Approaches conducted under Category II/III procedures require an autoland. In
cases of a failure that would require the aircraft to be manually flown prior to
touchdown, a missed approach would normally be the only safe course of action
(even if visual contact has been established with the touchdown zone)".cases of a failure that would require the aircraft to be manually flown prior to
touchdown, a missed approach would normally be the only safe course of action
A330:
"In (real) low visibility ops and BELOW the DH - Go Around required if:
- AUTOLAND warning light
- N/W steering failed (CAT 3). CAT 2 manual rollout control with rudder
- AP off at touchdown (CAT 3) CAT 2 Manual rollout control with rudder
and N/W steering
- no FLARE indication on PFD at 30’ (CAT 3), CAT 2 manual flare and
rollout".- AUTOLAND warning light
- N/W steering failed (CAT 3). CAT 2 manual rollout control with rudder
- AP off at touchdown (CAT 3) CAT 2 Manual rollout control with rudder
and N/W steering
- no FLARE indication on PFD at 30’ (CAT 3), CAT 2 manual flare and
Any of professional pilots of this forum, who caught LAND warning in real life, follow the instructions without thought, or try to assess the situation and land manually?
Cat 3B DH
I think one of the main lessons for the pilot in Low Vis situations is the decision making at DH or below.
In my opinion it is at this stage when if the pilot feels he has adequate visual cues and any of the malfunctions happen then it is better to land. (A330).
There have been trainees who "forgot" to flare and the landing gear can take the resultant rate of descent comfortably.
Each pilot machine combine has a decision making process of its own.
It is a rare situation and very few may have actually had this in real life. It would be better if the same is practised repeatedly in the simulator and analysed.
In my opinion it is at this stage when if the pilot feels he has adequate visual cues and any of the malfunctions happen then it is better to land. (A330).
There have been trainees who "forgot" to flare and the landing gear can take the resultant rate of descent comfortably.
Each pilot machine combine has a decision making process of its own.
It is a rare situation and very few may have actually had this in real life. It would be better if the same is practised repeatedly in the simulator and analysed.
Warning Toxic!
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Congratulations of reaching a milestone of the AN148 development! It's good to see some fine aeroplanes coming for the future.
Microburst2002's reply has a lot of impact. In true Cat3a conditions, having taken over manually and completing a touchdown, possibly in a 15kt crosswind, can you see enough lights to safely control the aircraft manually? It is a difficult call, but my thinking is anything that restricts capability at that stage of an AWOPs approach is an indication something is wrong with the aircraft, and that is not the time to be at a height of 15 metres in 200 metres visibility suddenly trying to fly the aeroplane! My feeling is 'go-around', but we have to remember in the real world, we have limited fuel available to us, the traffic congestion and reduced flow rate will make us reluctant to go around, and we would probably all grab the chance to get it on the ground!
Our official 737 AWOPs procedures are: for an autopilot disconnect below DH, even if visual- go around. How much diagnosis at that stage can you carry out, in an instant? You are likely to hit the ground and bounce anyway, so all attention should be on flying, not technical things apart from monitoring correct operation of Flare mode and Throttle retard.
Disagree! 'Forget to flare' and you are looking at a 700+fpm ROD. It doesn't take much more than that to put the gear up through the wing! Have we forgotten the MacDonnell Douglas DC9 test pilot video of the rear fuselage breaking off on a hard touchdown? Make no flare at all and you may well have a problem!
Microburst2002's reply has a lot of impact. In true Cat3a conditions, having taken over manually and completing a touchdown, possibly in a 15kt crosswind, can you see enough lights to safely control the aircraft manually? It is a difficult call, but my thinking is anything that restricts capability at that stage of an AWOPs approach is an indication something is wrong with the aircraft, and that is not the time to be at a height of 15 metres in 200 metres visibility suddenly trying to fly the aeroplane! My feeling is 'go-around', but we have to remember in the real world, we have limited fuel available to us, the traffic congestion and reduced flow rate will make us reluctant to go around, and we would probably all grab the chance to get it on the ground!
Our official 737 AWOPs procedures are: for an autopilot disconnect below DH, even if visual- go around. How much diagnosis at that stage can you carry out, in an instant? You are likely to hit the ground and bounce anyway, so all attention should be on flying, not technical things apart from monitoring correct operation of Flare mode and Throttle retard.
There have been trainees who "forgot" to flare and the landing gear can take the resultant rate of descent comfortably.
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GA below CAT IIIa is something we have to train every 6 months in the simulator, be it due to blocked runway, alignment with the runway edge instead of center or any other failure. Usually an AT failure is thrown in and it is expected that we continue with manual thrust.
For CAT IIIb there is no GA below DH as there is no DH for us, just a mandatory GA whenever the RVR drops below 75m. Since we exchange the old fail passive 737s at the moment rapidly with the fail operational ones CAT IIIa and DH will be a thing of the past soon.
For CAT IIIb there is no GA below DH as there is no DH for us, just a mandatory GA whenever the RVR drops below 75m. Since we exchange the old fail passive 737s at the moment rapidly with the fail operational ones CAT IIIa and DH will be a thing of the past soon.
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It's nice to hear that about AN148, Rainboe. Thanks. We just try to catch by the tail all of this Boeing-Airbus-Embraer 's company. And I'm sure we'll squeeze our swallow in this market.
Rainboe...
Please read the statement in correct context.... if one has been a trainer then he knows of the experience ... by the way do you know the ROD limits of your aircraft??? Please do not generalise the Boeing principles to the Airbus you are bound to come to incorrect solutions and spread a lot of misinformation.
.... how many times has one landed in actual Cat3B conditions and had a failure... I don't know of any. Neverthless one must prepare... nobody can tell the captain what to do at that stage.. it is his judgement and skill level. That is why one must prepare in the simulator
Please read the statement in correct context.... if one has been a trainer then he knows of the experience ... by the way do you know the ROD limits of your aircraft??? Please do not generalise the Boeing principles to the Airbus you are bound to come to incorrect solutions and spread a lot of misinformation.
.... how many times has one landed in actual Cat3B conditions and had a failure... I don't know of any. Neverthless one must prepare... nobody can tell the captain what to do at that stage.. it is his judgement and skill level. That is why one must prepare in the simulator
Warning Toxic!
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I don't want to get into an argument about a side issue, but you did say
Take a look at YouTube - DC 9 80 Hard Landing
Manufacturers don't publish ROD limits for landing- it depends on too many other factors like weight, landing on one leg first etc. But a straightforward no flare landing will put most aeroplanes in jeopardy.
There have been trainees who "forgot" to flare and the landing gear can take the resultant rate of descent comfortably.
Manufacturers don't publish ROD limits for landing- it depends on too many other factors like weight, landing on one leg first etc. But a straightforward no flare landing will put most aeroplanes in jeopardy.