Hi, just curious why I received a "No Autoland" message on the EICAS prior to takeoff? What did I do wrong and is it possible to re engage the ability to autoland after such a message.

Thanks in advance for your input.

Erwan de Quillien

Erwan,

In my experience that occurs when there is a disruption in electrical power (in my case caused by user error!).  Sometimes I have hit the apu power switches to disconnect them after start up when they have been already automatically disconnected.  When that occurs and/or after I re-disconnect them I get that EICAS warning.  I have also found that if I shut down the APU after start up before putting the packs back to normal I sometimes get that message as well.  If I put the packs on first I don't get it. Regardless, the plane will still actually auto land even with the warning as I understand it (although I have never tried) but I guess you are not supposed too!!  I am sure someone with greater knowledge than me can explain this better but I hope this helps.

Regards,

Todd Legon

Thanks Todd, I concede on one occurrence I disconnected ext. power before connecting APU generators which caused the message, however on the most recent occurrence it was after start up. I may very well have disconnected APU before turning packs to normal.

Thanks for your reply.

Erwan de Quillien

16 minutes ago, SoCal81 said:

I may very well have disconnected APU before turning packs to normal.

Packs are for air conditioning, so they're out of the equation here.

You need to ensure that power is not broken after getting the IRS ready. APU needs to take over from the GPU before the GPU gets removed. Engine GENs need to take over from the APU before it gets turned off. Be mindful of your start technique. If you're not using autostart, introducing fuel too early can cause problems with the engine start, which will also delay your GENs coming online.

Flying a plane is about being observant of what you're doing. Try to avoid just going through the motions...otherwise, you might have weird stuff pop up.

2 hours ago, scandinavian13 said:

Packs are for air conditioning, so they're out of the equation here.

You need to ensure that power is not broken after getting the IRS ready. APU needs to take over from the GPU before the GPU gets removed. Engine GENs need to take over from the APU before it gets turned off. Be mindful of your start technique. If you're not using autostart, introducing fuel too early can cause problems with the engine start, which will also delay your GENs coming online.

Flying a plane is about being observant of what you're doing. Try to avoid just going through the motions...otherwise, you might have weird stuff pop up.

Thanks Kyle, I will note the factors you mentioned and re read the start up procedure to ensure I am doing it properly everytime.

Thanks again.

Erwan de Quillien

As far as I know, it's the FCCs (Flight Control Computers) which generate the >NO AUTOLAND messages. Do the FCCs really know the IRUs are on DC power in this situation?

A disruption to AC power should just force the IRUs to Battery power until AC power was restored. There is no reason I can see why you would get NO AUTOLAND messages due to the IRUs. If the IRU internal AC/DC power switching process wasn't seamless, there wouldn't be any point having it. You would lose navigation ability. During DC power operation, the IRUs output the same (position/acceleration) data to the FCCs. The FCCs aren't powered anyway if the AC busses have failed, so I don't see why you would get a NO AUTOLAND message. For example, during power-up on the real aircraft, you don't get >NO AUTOLAND messages ... i.e. battery on, Standby Power switch to AUTO, etc...

Something isn't right here. Perhaps there is some kind of message screening which prevents the message/s appearing (flight phase, time delays, etc)

Pilots??? Current 747-400 engineers?

Cheers

JHW

 

Well, this is way beyond my pay grade, but you can probably find the answer way in the bowels of a maintenance manual somewhere or a Boeing engineer. The Autoland system looks at a lot of different items to determine that it has the redundancy necessary to be  Fail Operational (LAND 3), Fail Passive (LAND 2), or neither (NO AUTOLAND).

The system looks at stuff like the 3 FCC's, the 3 radar altimeters, the 3 ILS receivers, 3 different power sources, etc. If there is a single failure of 1 of these components, we downgrade to a No Land 3, or LAND 2 at slightly below 1500 RA during autoland. The system is constantly monitored and will give you an advisory message at any time.

On final, if the problem still exists, then it shows up as LAND 2 or NO AUTOLAND depending on the level of redundancy achieved. I do not think the IRU's are included in this, like John says. I think if you screw up with the power and de-power the jet, then it senses the loss of the required components for the redundancy required and generates the message. Once power is restored, no problem after that on reaching 1500 RA during autoland, everything is checked and found good, then LAND 3. That is my best guess.

Actually, I was trying to make the point that it's the FCCs which tell the EIUs the Autoland status (not the EIUs themselves looking at sensors). Unless the FCCs are powered and can somehow distinguish between IRUs running on DC or AC, then perhaps they could tell the EIUs there was a problem...  but I don't believe the FCCs care if the IRUs are running on AC or DC, as long as data is being provided.

If the FCCs powered up slightly before the other systems, then they perhaps would respond to sensor data loss. I can't imagine it would take long for something like a low powered ILS (MMR) receiver to power up. The Rad Alts may need a short warmup time to produce a stable frequency (my notes say 1 minute, but I can't say I've noticed the RAs requiring a whole minute to show data after pushing in the respective CBs).

The Caution messages only occur when multi-channel engaged. The Advisory messages show when not multi-channel engaged. The same Status messages appear on the lower EICAS (often with time delays to prevent nuisance messages). These are unlatched. There are some failures which do not affect Autoland capability. These generate latched Status messages. Which messages are appearing in v3?

I am just talking in general John, you are going to know a lot more about this then I do, not trying to challenge you at all. This is more up your avenue then mine as a pilot. As you know, they only tell us what we need to know to operate, which is probably good for most of us.

Erwan,

When something unexpected like the "NO AUTOLAND"  Status message occurs on the EICAS prior to takeoff - and provided you have set everything else up correctly for the departure and there are no other obvious faults!!! - it usually pays to turn OFF both Flight Directors and then turn them back ON again firs before you carry out any further troubleshootingt.  This message can appear if you happen to leave one or both Flight Directors on after an approach, which is why part of a normal After Landing Checklist calls for them both to be turned OFF, so that the AP/FD annunciations are cleared (i.e.reset) prior to the next flight. 

It pays to remember when you are having problems with any computer there is always an OFF or RESET button or, in this case, there is also an AP/FD disconnect switch!

Bertie Goddard      

Curious....

I just found two old videos in which I was pulling MMR CBs and Rad Alt CBs with the IRUs in align mode.

I waited about a minute and in neither video did the NO AUTOLAND messages appear (Caution, Advisory or Status). I wonder when the FCCs start looking at sensor data? After full IRU alignment? Only with at least one A/P engaged? I don't know if the FDs were on.

On 17/04/2017 at 5:10 AM, Qavion2 said:

Curious....

I just found two old videos in which I was pulling MMR CBs and Rad Alt CBs with the IRUs in align mode.

I waited about a minute and in neither video did the NO AUTOLAND messages appear (Caution, Advisory or Status). I wonder when the FCCs start looking at sensor data? After full IRU alignment? Only with at least one A/P engaged? I don't know if the FDs were on.

As I understand it, John, the autoflight system control (i.e. A/P, F/D amd A/T) is through the Mode Control Panel and the three Flight Management Computers.  I do not believe that the FCC's look at the autoflight sensor data when in IRU align mode; only when they are actually fully aligned AND operating in NAV mode.   Each A/P and its associated F/D essentially look at the same flight data information and during an ILS approach with all three A/Ps engaged, the three FCC's are powered from seperate electrical sources.  The AFDS with the least error signal will therefore control the aircraft at any given time on the latter stages of the approach and they can constantly switch if this changes (LAND 3 = Fail Operational and LAND 2 - Fail Passive). 

The EICAS advisory message NO AUTOLAND is only displayed if the level of redundancy prevents the aircraft from autolanding. However, I have seen this message after landing when both FD's have been left on after an autoland and the aircraft has exited the runway.  Unfortunately I don't have any detailed technical notes to confirm my suspicion, but I think that this particular message (and possibly the others associated with carrying out an autoland) are only active when in flight and, because both flight directors are still switched on, the autoflight system is sensing a LOC deviation to two FD's it displays a NO AUTOLAND advisory message.

Bertie Goddard              

9 hours ago, berts said:

However, I have seen this message after landing when both FD's have been left on after an autoland and the aircraft has exited the runway. 

Interesting....  Unfortunately, there is a lot of normal system weirdness going on below 200' and during rollout.,,, There are a lot of uknowns here.

When I first started learning about the autopilot, my first impression of the FD system was that it was just for indication (to keep the pilots in the loop) and had no bearing on what the A/P actually did. If this is the case, should FD switch position really affect the appearance of autopilot EICAS messages? I'm not sure what cycling the FDs really does, other than fix the FDs (sometimes one of the bars didn't appear if the FD was left on during IRU alignment...and was fixed by cycling the FDs. But it only happened a few odd times, so there must have been other factors in the mix.

Unfortunately, the longer I've been out of the business, the more I can't be sure of what I did or didn't see. e.g.a few times I recall seeing the NO AUTOLAND Status message after a flight. It usually turned out to be ILS beam deviation errors (aircraft flying in front of the ILS ground stations), but I can't recall if the pilots noticed any anomalies and logged them (or if I was the only one who noticed).

Probably the guy who designed this systems has long since retired... and no one really knows how the system was programmed any more :D

 

Cheers

 

 

I flew PMDG 747-8 SCEL rwy17R - ASADA - AER60 - EZE66 - GESTA - CF35 - SAEZ rwy3 After armed LOC from the FMA I saw FAC instead of LOC. But, just near landing EICAS message appeared as NO AUTOLAND. Is this an issue? Any ideas?

54 minutes ago, trisho0 said:

I flew PMDG 747-8 SCEL rwy17R - ASADA - AER60 - EZE66 - GESTA - CF35 - SAEZ rwy3 After armed LOC from the FMA I saw FAC instead of LOC. But, just near landing EICAS message appeared as NO AUTOLAND. Is this an issue? Any ideas?

You need an ILS for an autoland. If I remember correctly, if you try arming it too early, you might not get the localizer, in which case it's going off the final approach course, hence the FAC. At that point, you're performing an IAN approach rather than an ILS, which is why you got the NO AUTOLAND alert. For more information, have a look at the FCOM page 4.20.11.