777-206 ER question

[kolenb09]

Hi,

My name is Anthony and I have a question about the 777-206ER.
We have a flight planned from ZUUU (Chengdu) to EHAM (Amsterdam), and round the ETA of amsterdam we get the following meteorological information; Operational report Schiphol: low visibility procedures in use; RVR on ATC frequencies; main landing RWY06; expect ILS approach RWY06; wind calm; vertical visibility 100feet; FZFG; T-02/-02; Q1002; No change. ATC gives the following RVR's=> A/B/C:150 m. Looks like we have to do a ILS landing :D.
The problem is that before landing we will be confronted with a techinical problem of the left radio altimeter. The 777 has three radio altimeters. Is it possible to proceed to make a safe ILS landing and how can the problem be located in the cockpit (Is there an indication)? Are there manuals that I can look up to clear these answers cause I looked in the OM but couldn't find my answer there.
Thanks...

Anthony
HVA
Netherlands

[TURIN]

What does the MEL say ref L. Rad Alt Inop? :ok:

[BuzzBox]

'NO LAND 3' would be annunciated on the EICAS when the Rad Alt fails and shortly afterwards a RADIO ALT L message would be annunciated on the status page. The aircraft would then only be capable of a Cat 3A autoland, with LAND 2 annunciated on the PFD at 1500ft RA during the approach.

The RVRs you quoted (150/150/150) are below those required for a Cat 3A approach, so you wouldn't be able to do the approach.

The MEL is only relevant for dispatch and is not applicable when the aircraft is airborne.

[kolenb09]

Thanks for youre help.

I got one question left. I know that a cat 3b approach has to be done. But only a cat 3a approach can be made do to the left radio altimeter failure. Where can I look this failure up? Looked the OM up again and can't find information. Also looked in the QRH with no result.

[Evanelpus]

Should these questions be asked here?

It looks as though he's asking PPRuNers to solve actual technical problems/questions. Surely ask the technical people of the airline concerned.




Or is this a flight in FSX?

[kolenb09]

Well,

It is a project that I am doing right now. I Also simulate it in fsx ;). I am not asking for anyone to solve the problem for me. I am only asking where to find information about the problem and oppinions or suggestions. I am kind of stuk right now because I can't find any information about the radio altimeter of the 777-206ER. Only thing that I could find was that it has three radio altimeters, but can't find any information what happens if one fails (left, right or centre). That is why I seek for help.

[BuzzBox]

The fact that the L Rad Alt has failed is largely irrelevant to the flight crew and there's no associated procedure in the QRH. In-flight, the flight crew's actions will be dictated by any EICAS alert messages that appear on the upper EICAS. In this case, the failure of the L Rad Alt will result in a 'NO LAND 3' EICAS alert, due to the loss of redundancy. Various other failures will also trigger a 'NO LAND 3' EICAS alert. It doesn't really matter to the flight crew what type of failure triggered the alert; what matters is that the 'NO LAND 3' indicates that the aircraft's autoland capability has been downgraded.

From the QRH:
NO LAND 3 - "Condition: The autoland system does not have redundancy for triple channel autoland."

From FCOM3 (Flight Operations)\Supplementary Procedures\Flight Procedures\Low Weather Minima Operations:
"At 1500 ft. RA the AFDS changes to LAND 3. AFDS changes from 1500 ft to the alert height can occur at any time downgrading the system from fail operational to fail passive. This is indicated by LAND 2 on the AFDS. The AFDS must annunciate LAND 3 for CAT 3B operations and LAND 2 for CAT 3A or CAT 2 operations."

What that means is that with a 'NO LAND 3' EICAS alert, the aircraft cannot do a CAT 3B approach. It can, however, do a CAT 3A or CAT 2 approach, provided LAND 2 is annunciated on the AFDS when the aircraft passes 1,500 ft RA during the approach.

Hope that makes sense.

[Short_Circuit]

I am not 777 licenced (and should pull my head in) but can only speculate on what I know from the 767 & 744.
That is, during an autoland if an "Autoland Critical Sensor" fails (RA being one) AND below 200ft, the ASA indication in inhibited from changing from LAND 3 until Touch down. Not sure if the EICAS " L,C,R" RA MSG will also inhibit.
Above 200ft and an autoland critical sensor fails "LAND 2" will display. I think BUZZ is confirming this on the 777.

[BuzzBox]

Same on the 777. The alert height is 200ft RA. Below that height the AFDS will NOT change from LAND 3 to LAND 2 in the event of a failure, and all unrelated EICAS cautions are inhibited. The idea is that the flight crew should not interfere at that late stage, unless it is obvious that intervention is required. In the event of a critical failure that affects the autoland system, a NO AUTOLAND EICAS caution would be annunciated and the flight crew should go around unless they are in a position to continue visually.

On our aircraft there is no EICAS alert for a rad alt failure, only 'NO LAND 3'; don't know if that's a customer option or not. The only way you would know that a rad alt has failed is by looking at the status page, and there's no requirement to do that in-flight.

[kolenb09]

I really would like to thank you guys for youre answers and help. After doing some more research I also came to the answer that I needed. We can decide if the problem accures before the 200ft point or after. We decided to do it before so that means that we will have to divert to another airport which makes the flight more interesting. We wil divert to Rotterdam airport or Eindhoven where the weather is better.

[kolenb09]

I still have one question that bothers me. If the radio altimeter fails, do you first get an EICAS "no land 3" message on the EICAS display? And is this a warning that can be heard? Or do you first get the RAD ALT L message on the status page?

[BuzzBox]

I can't be sure of the EXACT timing, but in my experience the first message that would be noticed is the EICAS alert 'NO LAND 3'. Shortly afterwards a 'STATUS' prompt would appear on the upper EICAS, alerting the flight crew to the existence of a new status message. However, as I said in an earlier post, the flight crew's subsequent actions would be dictated by the 'NO LAND 3' message, not by the status message.

If the 'NO LAND 3' alert appears before 1500 ft RA during the approach, then it's advisory only and there's no aural alert. If, however, the 'NO LAND 3' alert appears after 'LAND 3' is already annunciated on the AFDS (ie below 1500 ft RA), then it becomes a caution and there will be an aural alert (ie a beeper).