Vhhh "no Autoland"

[math341c 0]

Hello guys so, not so long time ago the big SP1 update released for this plane. And of course i bought my favourite 300ER

So, to the point.

 

My first flight was from EKCH-OMDB. And yes i could fine make a autoland without problems with "Land 3". 

 But today i made my next flight. OMDB-VHHH.

I began to descent. And i set my apporach settings in fmc. Flaps, speed etc...

 

And ATC said that i may land on 25R, so i go to approach page, and selecting the runway and the stars and trans. Everything seems fine. The Nav radio with ils and course was also set automatically.

Im setting the Radio to "50" as i always do. So later when i was on 9000 feets, i heard a woman saying something like "Altimeter, Altimeter". I ignored that thing. She said it 3 times or so. I ignored because there was not any yellow warning or something what is wrong. 

So, i lined up with runway, localizer, localized fine. I clicked on approach. And VNAV controlled the height down, so i could capture the glideslope. So i reach my last star before runway, and i see the diamond is not moving. And about 6 miles from runway, i get "No autoland" message. And i hear the computer saying "glideslope, glideslope"

I decided to go around. I clicked on vertical speed to go up, and here is the strange thing. 

When the plane began to climb, then the plane was suddenly on "LAND 3" and autopilot tried to get the plane down to runway. But it was impossible i was already too high. 

So i tried again to make the approach. And the same happen. When i began to climb, the diamond moved like the speed of light to the middle, and the plane was on"land 3", but first when i began to climb it happened.

 

What am i doing wrong here? Thank you if you want to help me. I really want to enjoy this plane.

 

I ended up to land with controling the vertical speed manually, and i made a medium touch down, not the lightest.

 

Sorry for bad eng.

[Mike777 163]

 

 

i heard a woman saying something like "Altimeter, Altimeter". I ignored that thing. She said it 3 times or so. I ignored because there was not any yellow warning or something what is wrong.

 

Hi, math341c,

 

Haven't had this experience.  Only thing I can think of is that the altimeter setting (using "B" command) wasn't set properly and there was a discrepancy between radio altitude and barometric altitude which was detected when you descended enough to activate radio altimeter.  Did you reset the altimeter from standard to normal, and did you press B?  Don't know why it would go into LAND 3 when you started to climb.

 

Mike

[math341c 0]

Hi, math341c,

 

Haven't had this experience.  Only thing I can think of is that the altimeter setting (using "B" command) wasn't set properly and there was a discrepancy between radio altitude and barometric altitude which was detected when you descended enough to activate radio altimeter.  Did you reset the altimeter from standard to normal, and did you press B?  Don't know why it would go into LAND 3 when you started to climb.

 

Mike

Thanks for answer. Yes i always pressing B, before i need to land. But that radio which is marked in green, what should i set it to? Im always setting it to "50"

[Mike777 163]

 

 

But that radio which is marked in green, what should i set it to? Im always setting it to "50"

 

There are different kinds of approaches that have different minimums which you can find by looking at the charts for any given airport.  But a good rough approximation would be 200 feet.

 

Regarding "no autoland,"  try having at least flaps 15 and speed no greater than 180 by 1500 ft AGL (above ground level) -- this would equate to approximately five miles from touchdown.  See if you can get an autoland then.

 

The moderators of PMDG forums want you to sign your full name

 

Mike

[math341c 0]

There are different kinds of approaches that have different minimums which you can find by looking at the charts for any given airport.  But a good rough approximation would be 200 feet.

 

Regarding "no autoland,"  try having at least flaps 15 and speed no greater than 180 by 1500 ft AGL (above ground level) -- this would equate to approximately five miles from touchdown.  See if you can get an autoland then.

 

The moderators of PMDG forums want you to sign your full name

 

Mike

Thank you very much for helping me. Flaps was on 30 as i always land with. and speed what 152. Where can i see my AGL level. Where to find the information what i have to set the minium to? And i land with vnav. VNAV should control the height and vertical speed, so i can catch the glideslope.

[Mike777 163]

 

 

Flaps was on 30 as i always land with. and speed what 152. Where can i see my AGL level. Where to find the information what i have to set the minium to? And i land with vnav. VNAV should control the height and vertical speed, so i can catch the glideslope.

 

AGL is shown on the radio altimeter once you descend to @ 2500 ft.  But you can just use the regular altimeter, as long as you know the altitude of the airport.  The radio altimeter might be misleading if there are hills on the approach.   Minimums are noted in the approach chart for each runway.  For US runways you can find the info at flightaware.com.  For other countries there is usually an aeronautical agency with charts. This is true for Great Britain, France, Japan, Australia and many other countries.  Google or Vatsim can help.

 

My experience is that VNAV is fine for the approach (LNAV/VNAV with APPROACH armed) but you have to monitor it and understand how it works.  If you dial in a speed of 152 but you are going 210 VNAV will slow down the descent to reduce speed. You can wind up too high.   So you can't just count on VNAV.  You have to "help" by adding drag, by extending flaps as far as speed allows, using the airbrake, and lowering gear earlier than usual if you are going too fast.  My experience has been that the 777 is HARD to slow down, even compared to other 777 simulations and certainly compared to other, smaller aircraft (no criticism of PMDG here -- they most likely got it right).  You can use legs of level flight on the approach, if any, to slow down -- much easier than during descent.  Also, most of the time the speeds set by the flight plan that VNAV follows are too high -- you need to intervene and set lower airspeeds.  240 ten miles out is too fast.  So use VNAV but don't assume it will do what you want.  A kind of "Trust but verify" situation. 

 

Mike

[math341c 0]

AGL is shown on the radio altimeter once you descend to @ 2500 ft.  But you can just use the regular altimeter, as long as you know the altitude of the airport.  The radio altimeter might be misleading if there are hills on the approach.   Minimums are noted in the approach chart for each runway.  For US runways you can find the info at flightaware.com.  For other countries there is usually an aeronautical agency with charts. This is true for Great Britain, France, Japan, Australia and many other countries.  Google or Vatsim can help.

 

My experience is that VNAV is fine for the approach (LNAV/VNAV with APPROACH armed) but you have to monitor it and understand how it works.  If you dial in a speed of 152 but you are going 210 VNAV will slow down the descent to reduce speed. You can wind up too high.   So you can't just count on VNAV.  You have to "help" by adding drag, by extending flaps as far as speed allows, using the airbrake, and lowering gear earlier than usual if you are going too fast.  My experience has been that the 777 is HARD to slow down, even compared to other 777 simulations and certainly compared to other, smaller aircraft (no criticism of PMDG here -- they most likely got it right).  You can use legs of level flight on the approach, if any, to slow down -- much easier than during descent.  Also, most of the time the speeds set by the flight plan that VNAV follows are too high -- you need to intervene and set lower airspeeds.  240 ten miles out is too fast.  So use VNAV but don't assume it will do what you want.  A kind of "Trust but verify" situation. 

 

Mike

Let me not get you wrong.That minimum thing is the knob on the other side, not where baro is? And when i touch the minimum knob i will get a green thing on the PFD called radio, and i need to set it to the airport height? And can i not see the airport height in fsx map? I own the lastest imagine sim vhhh so it should be updated? 

 

And i always land with vnav. Because when you select the ils runway in fmc, it make some stars, and the last star before runway, should be configured, so the plane can catch the glide slope.

[thannyd 4]

Minimums can be set in DH or BARO (MDA - minimum descent altitude).

 

DH is the height above ground where you must make a go around if you do not see the runway and/or approach lights. 

 

MDA is the minimum altitude you can descend to when flying a non-precision approach (NDB, VOR etc) or a cricling approach. You can stay at that altitude after descending untill you are at a missed approach point, usually a VOR, or DME from a VOR or NDB or even time from the final approach fix. 

 

Here the more expanded explanation from wikipedia:

Decision height

A decision height (DH) or decision altitude (DA) is a specified lowest height or altitude in the approach descent at which, if the required visual reference to continue the approach (such as the runway markings or runway environment) is not visible to the pilot, the pilot must initiate a missed approach. The specific values for DH and/or DA at a given airport are established with intention to allow a pilot sufficient time to safely re-configure an aircraft to climb and execute the missed approach procedures while avoiding terrain and obstacles.

 

 

Minimum descent altitude (MDA)

The minimum descent altitude (MDA) is the lowest altitude (relative to MSL) to which descent is authorized on final approach, or during circle-to-land maneuvering in execution of a non-precision approach.^[4] Unlike with DH or DA, a missed approach need not be initiated immediately upon reaching the altitude. A pilot flying a non-precision approach may descend to the MDA and maintain it until reaching the missed approach point (MAP), then initiate a missed approach if the required visual reference was not obtained. An aircraft must not descend below the MDA until visual reference is obtained, which differs slightly from a DH/DA in that while the missed approach procedure must be initiated at or prior to the DH/DA, because of its vertical momentum, during a precision approach an aircraft may end up descending slightly below the DH/DA during the course of the missed approach.

If a runway has both precision and non-precision approaches defined, the MDA of the non-precision approach is almost always greater than the DH/DA of the precision approach, because of the lack of vertical guidance on the non-precision approach: the actual difference depends on the accuracy of the navaid upon which the approach is based, with ADF approaches and SRAs tending to have the highest MDAs.

 

 

Also see an example of the differences in DH and MDA on an approach plate. 

 

 

You can see (in left bottom) that the decision altitude (DA) for the ILS approach is 228 feet above mean sealevel. The decision height is the number behind that (200') so 200 feet in this case. That's what you set in the green 'radio' numbers. 

 

One square to the right you see the minimums for an LOC (localizer approach) this means when the glideslope of the ILS is broken or in maintanence, hence the (GS out). The minimums of the LOC approach are an MDA of 360 feet above mean sealevel or 332 feet above the ground. In this case you set the green 'baro' to 360.

 

Both minimums are ment for a manual landing so no Autoland. (you can practise autoland of course but that's for training and mostly currency reasons). That's why the minimums of this page are called CAT I minimums. And every IFR equipped aircraft can fly this approach. 

 

Again different story for CAT II and CAT III a, b, © approaches. 

 

Hope this clears a few things up. 

 

 

[math341c 0]

Yes. Thank you very much. So i don't need to set any minimums to autoland?

 

Math.

[jeffhunter 0]

No, they're not required.  You just won't get the correct call-out re minimums.  I can't understand what the problem could have been re VHHH 25R.  Taking a punt, can I enquire about your navdata? I haven't got the -300, but did you get a navdata update with it?

 

cheers

 

jeff hunter

[hopskip 253]

I have seen No Autoland come up on a turbulent approach where my speed ended up below vRef and close to the yellow band.

 

I have also seen no Autoland come up when I was a bit too fast on approach and still didn't have landing flaps set through around 1600ft.

 

If I am completley stable, flap 25 or 30, gear down, speed Vref+10 or so, speedbrake armed, APP mode with LOC/GS captured/green on the PFD and configured for the autoland, the thing will autoland.

 

If any of these points are not completed by a certain altitude (can't remember the altitude, by memory there's a check for speed/gear at 1800ft and another check at 800ft) Then the land III will drop out.

 

It's basically the Autopilot saying "Some fancy flying is required to get the aircraft configured, I'd suggest going around!"

With a bit of wrestling you might salvage the approach.

 

Remember that the Airspeed Indicator does not go to vref+5 on it's own. You need to manually change it to your approach speed at some point. Unlike the 737NGX, the 777 will never automatically select an autothrottle speed below 170kts in Vnav, even if the actual vRef should be 140kts.

 

And I think the 800ft check needs to have your speed below about 165kt for the autoland to be active.

 

Additionally, you should have entered ZFW or Gross weight in the FMC before takeoff, and have a flap reference selected, and have the correct ILS (or auto-selected from FMC runway selection) dialled in (NAV RAD).

[Mike777 163]

Thanks, Thanny, for your very informative discussion of DH and MDA.

 

The 777 FCTM Chapter 5 has a good discussion of approaches, including various minima and use of the radio altimeter.  

 

Mike

[math341c 0]

No, they're not required.  You just won't get the correct call-out re minimums.  I can't understand what the problem could have been re VHHH 25R.  Taking a punt, can I enquire about your navdata? I haven't got the -300, but did you get a navdata update with it?

 

cheers

 

jeff hunter

Im using 1408 from Navigraph. It´s strange. The VNAV supposed to guide the plane to the glideslope after localazing.

 

Math

[Mike777 163]

 

 

Im using 1408 from Navigraph. It´s strange. The VNAV supposed to guide the plane to the glideslope after localazing.

 

One thing to take into account is that when you select a VNAV approach it doesn't autotune the ILS frequency.  So you need to do it manually.

 

Mike

[math341c 0]

One thing to take into account is that when you select a VNAV approach it doesn't autotune the ILS frequency.  So you need to do it manually.

 

Mike

Before i descent i set my approach route in Approaches page. And when i do that, ILS  frequencies are autotuned.

 

Math