A question about autoland

[caucatc]

I have a question, tonight a Delta Airline pilot said: be advised, we will use auto landing approach. I have never experienced this before, I ask another pilot, he said it is non sence to say this to controller, does anybody know why he said this? It was CAVOK that night, do pilots use another way to land some other time?
As far as I know, usually pilot will fly with autopilot and visual runway before decision height, then disconnected autopilot at certain altitude, is that what pilots usually do ?

[Crazy Voyager]

I'm not an ATCO; but my guess is that he wanted to make sure the ILS sensitive areas were protected. Cat II and III approaches require a larger protected area (at least at some airports but I belive this is always true?) and if it's not protected the system might not function properly.

That's my guess, as a wannabe that is (so wait for the professionals to get back and have their say).

[Chilli Monster]

Crazy Voyager is quite right. Sometimes crews will use Autoland in VMC conditions for crew training (It's better to make your mistakes where you can see things going wrong rather than in real CAT II / III conditions).

In this event - you will often be told just for your own information BUT it is nice if the crew tell you whether they require FULL PROTECTION (Use of CAT II / III holding points) or not. If they don't say - it's often a good idea to ask them, so that you can relay that information to the Tower and they can operate accordingly.

[caucatc]

Thank you guys, this is first time to be informed autoland approach, so I did not know what to do at that time, please tell me more about autoland, we were operating CAT1 ILS, not CAT2, is it true to say that pilot can still use autoland in CAT1 ILS, or they can use autoland at anytime?
One more question about autoland, if pilot engaged autoland approach, does it mean autopilot will operate aircraft until it touchdown ?

[Chilli Monster]

1) They can use Autoland if the aircraft is so equipped at any time. However, if the airport is operating to CAT I conditions then the crew have to be aware that the antenna sensitive areas do not have the requisite protection and as such should be ready to disengage and fly manually should it be required below 200ft.

2) Autoland is exactly as it says - the autopilot will land the aircraft, retard the throttles, autobrake and bring the aircraft to a complete stop on the runway if necessary. All the crew have to do is taxy the aircraft to the terminal.

[caucatc]

Chilli Monster
Is it right to say pilots only operate autoland approach when CAT2 or CAT3 ILS operating?
Cheers
Jack

[Blockla]

Is it right to say pilots only operate autoland approach when CAT2 or CAT3 ILS operating?No they can make an autoland in VMC when making a visual approach, for practice... They may request 'sensitive area protection' when doing so, they may not, they can still autoland without the protection but pilots need to monitor the approach very closely in case of interference.

[caucatc]

Yes, the pilot did not request for a protection of sensitive area(I do not know if we were talking about the same thing, because we were told that is the critical area, it is a area that if there is a vehicle in that area the glide slope signal will be affected), so if pilot said he wanted to do a autoland approach, do I need to ask ground staff to protect critical area at least like a CAT2 ILS operation ?

[Tarq57]

cauatc, I don't know, but I think that if you are operating to Cat 1, you shouldn't need to.
But it may be advisable to inform the pilot of your current status (Cat1, or whatever it is.) I would hope the crew would be aware of that in any case.

Refer to what your unit documentation states concerning differing procedures with any category change. For example, ours has a brief list of the weather criteria that requires a change, and which holding points to use (or rather, which not to use) and protection area needed.

[fujii]

An ILS can be CAT I, II, IIIa, IIIb or IIIc. CAT I has aircraft critical areas surrounding the GP antenna and the LOC antenna. The GP critical area is fairly small whereas the LOC critical area is within the runway strip and within 1 mile of the LOC antenna. These are often more accurately mapped in documents to assist ATC. Within the aircraft critical areas there are smaller vehicle critical areas. Aircraft and vehicles in these areas can disturb the ILS signals to aircraft on final which may cause deviations from the ILS path.

For CAT II or III operations there is an added sensitive area surrounding the runway. It is 90 metres wide at the LOC antenna and splays out for about 1 1/2 miles to 180 metres wide, then parallels the runway to north of the threshold.

During CAT I or visual conditions aircraft notify ATC if they are making an autoland so ATC can advise the crew whether the areas are protected, which they are generally not due to normal surface operations. Crews make practice autolands both for crew and aircraft currency. An assessment of the landing can then be made taking protection into consideration.

During CAT II or III operations, all landings are autoland and the critical and sensitive areas are protected when an aircraft is within a 4 and 2 mile final respectively. This is done by spacing landings and departures to allow preceding aircraft to vacate the areas and by managing other surface traffic.

Low visibility operations are one of the times in ATC where there is less traffic but the tower works harder to manage it.

[Denti]

Actually CAT II and III operation can still be manual approaches and landings, however most are automatic, it is just not a requirement given the right equipment.

[fujii]

Depends on where you are, your country's regulatory authority and airline approval. Down here autoland.

[Denti]

Where is that? As far as i know manual CAT III is approved in the US and all of europe and quite a few other countries. Just need a head up guidance system designed for the task which has been available since the early 80ies in 737s and thereafter in many other planes (for example CRJ and Dash 8), most of which are only CAT III approved with a system like that (aka no autoland available).

[Spitoon]

Cat I, II and III are largely aircraft operatioanal matters and determined principally by the decision height associated with the approach. The way the aircraft is to be operated, that is to say what equipment must be used and how much of the approach and landing must be conducted using 'automatics' is usually determmined by the aircraft operator (typically following the equipment manufacturers' recommended procedures and international standards) and approved by the operator's national authorities.

The ground equipment will be defined/authorised to provide a service that supports Cat I, II or III. The differences between Cat II and II requirements are small but both require more standby and back-up facilities. The surrounding terrain is also a factor as it can cause the signal to be disturbed. The equipment will not be authorised unless the transmitted signal meets particular specifications. The runway and approach lighting will also have to meet certain minimum specifications to support the various categories of appraoch. There is sometimes a trade-off between sub-standard lighting facilities and decision height which means that, say, whilst a Cat III approach might otherwise be possible an increased decision height means that only Cat II approaches are approved.

The dimensions of critical and sensitive areas are determined by the antenna array and the way that it radiates. Whilst there used to be 'standard' sizes, modern anrennas are often far less susceptible to interference from nearby aircraft and vehicles and so the restricted areas can be far smaller. Where it is beneficial to operations some States allow surveys to be carried out and permit any operations that do not cause the ILS signal to be disturbed. Consequently, distances and operational procedures quoted for one airport do not necessarily apply at another.

As others have pointed out, pilots can make practise Cat II/III approaches in conditions that do not require them. There seems to be a broad range of interpretations of what should happen when a pilot says he/she will make a Cat II/III autoland for practise - some pilots appear to assume that the ground equipment will be fully protected as would be the case in poor weather, others mention it for information only. One airport that I worked at said that I had to refuse the approach!!

caucatc, if your procedures do not specifically tell you what to do in this situation I suggest that you simply say "Roger, no low visibility procedures are in place" or something similar.

HTH.