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Trouble landing 777-200LR

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Re: Trouble landing 777-200LR

Postby cgdae » Tue Sep 01, 2020 12:04 pm

tdammers wrote in Tue Sep 01, 2020 11:25 am:Landing speeds: with a large airliner like the 777, the landing reference speed (Vref) depends hugely on weight. Between operating empty and max landing weight, there is a 50% difference, and clearly a landing speed that works well for a 140-ton aircraft is going to have you drop out of the sky when you weigh 210 tons; and conversely, the right landing weight at 210 tons is going to make your float or nosewheel-strike when you're landing empty.

So what you need to do is find a resource for those landing speeds. Real-life pilots get a preliminary calculation from their dispatchers, who use dedicated software to calculate all the landing parameters; but it can also be done using tables from the FCOM, and in most modern airliners, the FMS can do the calculation as well.


This is slightly off-topic, but in "The View From the Hover", John Farley (Harrier test pilot) writes about targeting a particular angle-of-attack value (aka alpha) rather than a speed when landing, because the same alpha value works regardless of aircraft weight. He also said that if he was to buy his own private plane, he would have insisted that it have an instrument that shows the current alpha.

He gave a rather nice example of this when testing a cargo aircraft. The co-pilot was panicking trying to find the correct approach speed for their weight in the manual, only to find that Farley was already flying at almost the exact recommended speed because he'd simply targeted the alpha value that he'd seen on previous landings.

- Jules
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Re: Trouble landing 777-200LR

Postby Johan G » Tue Sep 01, 2020 11:02 pm

cgdae wrote in Tue Sep 01, 2020 12:04 pm:[...] John Farley (Harrier test pilot) writes about targeting a particular angle-of-attack value (aka alpha) rather than a speed when landing, because the same alpha value works regardless of aircraft weight.

Considering his experience, I would definitively trust that to hold true. :)

Also, one of my favourite aviation theory websites, "Eddie's" Code7700.com, have an excellent article, Angle of Attack, if you happen to like a mix of theory and anecdotes from real life lessons. The fact that the proper AoA is the same no matter weight or configuration have saved "Eddie" more than once.
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Re: Trouble landing 777-200LR

Postby Isaak » Wed Sep 02, 2020 6:10 am

Johan G wrote in Tue Sep 01, 2020 11:02 pm:Also, one of my favourite aviation theory websites, "Eddie's" Code7700.com, have an excellent article, Angle of Attack


Very nice reading, I enjoyed it!
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Re: Trouble landing 777-200LR

Postby flyer » Thu Sep 03, 2020 1:03 am

tdammers, thank you for your response.

I use all of FG's defaults and fly directly, so I have all the details about flight weight, fuel etc etc.

Recently, (as I mentioned upthread) I have selected the tab "position aircraft in space" and set 150kn as the speed.
For some reason even after FG reports that autopilot is disengaged, it continues to set my airspeed. This is annoying
because when trying to land the autopilot is still trying to maintain 150 knts. Yet, when I finally do touch down the
autopilot will then disengage airspeed control. This interference makes landing more difficult; from the flying feel that
I have gained 125 would seem a better landing speed to strive for with my current setup. The FG plane information
for the 777-200 mentions that 5 knots over stall speed is what to aim for on landing. I am fairly sure that 150 is well
over stall speed. Would one way to estimate the landing speed be to reduce airspeed until the controls warn of stall?

Thank you also for clarifying V1,Vr and V2. On the runway that I have been using the most often V1 and Vr are announced
almost at the same time (V1 first and then Vr). I suppose that technically an airplane should not be allowed to takeoff from
a runway that has such a setup as you would then need to commit to takeoff (V1) before actually achieving rotation speed (Vr).

My early experiences with jet takeovers were not encouraging. I typically made a hard rotation at V1from takeoff and then
I frequently stalled out. My latest strategy of staying on the runway for as long as possible has resulted in high liftoff speed
and no stall problems. Another strategy that I am using is not climbing out as fast. Before I would climb out at the 10 or even
20 HUD indicator angle and this would also lead to stall out. When I have used a more gradual climb with a 0 HUD indicator
angle I can gain speed and altitude at the same time. What is the recommended climb out angle?

I see the PFD on the Inboard DSPL in front of the yoke. How do I turn the knob to the PFD setting? I am trying to click on knob
and it isn't turning. Is there another way to achieve this on FG? Having all the V information will be of great help with takeoffs and
landings.

I have shied away from the speedbrakes on the 777-200 because it has not been clear to me when they are engaged. I have been
able to incorporate thrust reversers with a simple push of Delete (though on occasion they have not engaged and I have tried to
land with thrust and not anti-thrust). I appreciate with FG that they have a distinct reverse thrust sound that indicates that they are
engaged.

With Speedbrakes I am not as clear what to do. Toggle Speedbrake with ctrl-B, toggle arm Speedbrake with =, increase Speedbrake with },
and decrease Speedbrake with {? What is the sequence involved? Toggle arm , then toggle , then increase/decrease? That is, = --> ctrl-b --> }/{?
Is some indicator that allows one to know whether the speedbrakes are engaged?

OK, I have found the big arm in the center control panel with Speedbrake (=Autobrake?) written on it. I can see how the arm moves when I press =, ctrl-B and { and }.
Is the arming stage with = a safety stage? the default Speed brake position should be in the top position labeled down? So the sequence is from "Down" toggle with =
and the increase with }. Or if you want to go directly to the maximum Speedbrake position of up it looks like one could simply press ctrl-B. What i think might be
helpful is if one could present the Speedbrake level and then use a separate arm to engage it. This would reduce one step if things became rushed.

With flaps I am not so sure now. I am trying for a fast takeoff speed. Sometimes this is perhaps up to 160+. I am not sure whether using flaps is even worth it.
With a fast takeoff speed I need to disengage the flaps almost right away because the maximum flap deployment is ~180 knots. BTW what is the neutral flaps
position flaps up or flaps down? When I have taken the chase view, flaps down seems to be neutral. I am pretty sure that the correct keyboard command is
] to engage the flaps, though I am not so sure anymore.

Does FG have an onboard computer that can calculate whether a landing abort should occur upon speed and braking ability? The flight computer often
gives me warnings and cautions during flight about stalls or angle, flaps etc., though I do not recall ever receiving a warning that I did not have enough
braking ability. I am told about the amount of runway left, yet the critically important calculation of projecting my deceleration speed and calculating
needed runway length is conspicuous absent. This feature of FG does not seem plausible. A 3 line computer program to make this calculation
would have to be included in modern flight computers.

I have noticed on landing that pushing forward on the yoke seems to help slow the plane down. Is this observation correct?
Also can I engage reverse thrusters even before landing? It can take quite a while to achieve full reverse thrust, so it would
be helpful to have reverse thrust at a low throttle even before landing.

I have largely ignored trim in my flying to date. I have not adjusted this to date for takeoff. I am not sure what would be needed for trim adjustment to take off.
Totally unclear what A/T is (autothrottle?). Departure speed is 200-250? I have rotated sometimes at 110 (That is when the flight computer calls out V1)!
I have always manually flown the plane. I suppose that should begin to investigate the autopilot features more closely.

For landing is there some indicator that the flight computer could give that would tell you the angle of the runway to the airplane. This would be very helpful. Instead of
simply eyeballing one could have a precise measurement even when aways out when landing manually. Often with a manual landing one is not sure whether adjustments
are actually helping with proper aircraft alignment.

This is good to know about disengaging autothrottle. This is the problem that I have been having. Autothrottle only disengaged after I landed. Disengaging autothrottle manually will make it easier for me to land. I really like the "butter landings". Sometimes it is not even obvious that I have landed using this smooth approach. The problem
with other landing types is that you can have recoil or skips and then maintaining aircraft control can be a problem.

In terms of real life 777-200 landings, does FG simulate it well? My suspicion is that with so much mass involved that the plane would land like a truck. Aircraft control is probably much more stable than FG is suggesting. If one were to land on grass with the 777-200 would it probably shear off the front landing gear?
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Re: Trouble landing 777-200LR

Postby flyer » Thu Sep 03, 2020 4:28 am

This is really great!

I have been motivated to learn about the autopilot.
I did not realize how easy it is to engage it.
From the cockpit view the A/P is just below the middle divider of the front window.
There were some problems engaging it at first, though when I normalized the flight controls (airspeed etc.),
then it engaged. I also had some trouble engaging the speed control. Yet, when I clicked F11 I was able to
do this manually and then this showed up in the AP cockpit controls and also on the blue/orange screen by the
yoke.

I am not yet clear on how I can reset the autopilot controls, though to have it flying on manual is a great first step.
To reset I mean e.g., change the airspeed. When I click on the IAS/mach checkbox in the autopilot settings screen
it appears to automatically disengage. It wants to stay at the preset setting and not change. However, this is a
big advance. The plane is now flying with heading, altitude and speed autopiloted!!

I wasn't sure what IAS meant. Apparently it is indicated air speed. I am holding at 14,000 feet and the IAS is 320 but
the HUD reads 155?
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Re: Trouble landing 777-200LR

Postby flyer » Thu Sep 03, 2020 4:58 am

I just watched a 777 autopilot landing!!
Wow! It lands itself?

I will give this a try when I can.
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Re: Trouble landing 777-200LR

Postby Pancho » Fri Sep 04, 2020 2:46 am

Flyer
I hope this is what you requested.
AP ILS landing w/ HUD

https://www.youtube.com/watch?v=Wgu9LDoJrqM
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Re: Trouble landing 777-200LR

Postby flyer » Fri Sep 04, 2020 10:05 pm

Pancho thank you very much for the video!
Very impressive!

It stayed right above the 10 line the whole way in.
I was not sure what the proper glide slope should be, though using the 10 line gives
you the smoothest possible landing.

However, I am about surprised your low approach speed.
135? The 777-200 video I saw online landed closer to 170.
Yet, I guess that if going in with an empty fuel tank and perhaps few passengers,
then 135 would be correct.

One of the annoyances that I have found on some runway approaches is trees.
Have those trees really been planted on the approach to that runway? It is very
difficult to believe. I would prefer if nearly the entire airfield were essentially
obstacle free. Some airports even have a flagpole or something at the end of
the runway. The problem is that on landing one worries and gives these
obstructions a wide berth, which then subtracts away one's runway length.
I suppose though that some runways might only place these objects on the
"end" of the runway (not the start).

I have been able to engage the Land3 autolander on FG. One problem that I had
was that after landing the plane slide off the runway. I now realize after watching
your video that the pilot is expected to steer and brake upon landing. I had thought
that perhaps the autolander would completely automate the landing.

I think that I have now figured out the autobrakes as well. The video
says to arm them with = and then say set to level 2 autobraking.
No further action was required for these autos to engage, so perhaps
once landing the brakes automatically deploy. So, the 777-200 has quite
a number of available braking systems: autobrakes, reverse thrusters,
flaps, the brakes and possibly also pushing forward on the yoke. Not sure
yet about spoilers (Are the speedbrakes the same thing as the autobrakes?).


Great! I am figuring out how to use the Land3. Yes, it appears that one
must steer and apply brakes even with Land3. One of the few remaining
problems that I am having is finding the glide slope into the runway.
I suppose the best idea would be use the altitude from the route manager.
The flight panel does not seem to give good clues whether one is our of
range for the glide slide. However, the best idea is probably to
start the approach just at the suggested altitude and then have a vertical speed that
is below the 10 line. This way you will know that you will hit the glide slope.
What is the pink rectangle that appears on the flight screen? There must
be some clue to help line up the altitude.

I think I understand now. When the pink open diamond is above the 0 on
the flight screen, you are below the glide slope and either need to increase
altitude or wait for the glide slope to reach you from above. The latest problem
that I have had is for some reason while I was on LNAV, ALT, and SPD on
autopilot, somehow the flight computer slide off the flight route and was not
lined up properly for a landing.

I am now comfortable using the autoland. To line up with the glide slope all you need
to do is wait for the pink open diamond to appear on the flight screen by the yoke.
If the pink diamond is above the 0 altitude all you need to do is add some altitude
and then you will meet up with it. As soon as it turns to solid pink you can push the
approach button on the autopilot settings screen and the flight computer will
take it from there.

Yes, autoland is very smooth now. When I started out, I was having trouble contacting
the glide slope. If you do not find the glide slope fairly quickly, then you can almost
be over the runway before you set the approach. Best idea is to find the glide slope ~2,000
feet and then reach up to meet up with and then press the approach button on autopilot.
This way autoland has control well before the runway.
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Re: Trouble landing 777-200LR

Postby Octal450 » Sat Sep 05, 2020 2:20 pm

cgdae wrote in Tue Sep 01, 2020 12:04 pm:[...] John Farley (Harrier test pilot) writes about targeting a particular angle-of-attack value (aka alpha) rather than a speed when landing, because the same alpha value works regardless of aircraft weight.


This is not done with airliners.

Kind Regards,
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Re: Trouble landing 777-200LR

Postby flyer » Sat Sep 05, 2020 3:21 pm

I am now trying to autoland without using the route manager.
A problem that I have encountered is that the NAV frequencies
do not appear to always show up on the map when data is selected.
Is there a file/url that has all of this information?
Without the nav frequency even when I was directly on top of the flight path and glide
path to a runway, FG did not localize.

When I am flying without presetting route manager, can I selected fixes and a runway and land?
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Re: Trouble landing 777-200LR

Postby flyer » Sat Sep 05, 2020 7:25 pm

Could I create a route manager flight while in flight?
For example, could I head for a fix and then on the fly add the fix to route manager and then select
other fixes that the autopilot will find and fly towards?

I am getting better at this!

I have been practicing my autolands using the preset routes and then adding in some of my own waypoints.
For some reason autopilot can get distracted and is then thrown off course. What I have found is that with
route manager I can get back on track by jumping to and activating a waypoint. The one ongoing problem that
I am having is vertical lock. It is fairly easy to center the locator on an approach. The problem seems to be
hitting the glide slope. Sometimes I am almost right on the glide slope and the autopilot does not seem to want
to recognize that it should engage. I have had to fight with the autopilot almost right up to the runway. Finally
Land 3 engages and it is a fully automatic landing. I am not sure why finding the glide slope is so tough. My latest
is to stay below the glide slope and just let it reach me. Yet, I have tried this several times and sometimes the glide
slope will fall below me without locking in on the approach.
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Re: Trouble landing 777-200LR

Postby Pancho » Sun Sep 06, 2020 4:12 pm

flyer

To get ILS and HDG information for runways, use this URL, click on "nav" and type the airport code
Good day

http://mpmap02.flightgear.org/
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Re: Trouble landing 777-200LR

Postby tdammers » Sun Sep 06, 2020 7:43 pm

flyer wrote in Sat Sep 05, 2020 7:25 pm:Could I create a route manager flight while in flight?
The one ongoing problem that
I am having is vertical lock. It is fairly easy to center the locator on an approach. The problem seems to be
hitting the glide slope. Sometimes I am almost right on the glide slope and the autopilot does not seem to want
to recognize that it should engage. I have had to fight with the autopilot almost right up to the runway. Finally
Land 3 engages and it is a fully automatic landing. I am not sure why finding the glide slope is so tough. My latest
is to stay below the glide slope and just let it reach me. Yet, I have tried this several times and sometimes the glide
slope will fall below me without locking in on the approach.


The usual method is to intercept the localizer first, while approaching the glideslope from below. This is what practically all published ILS approaches have you do. Intercepting from above is problematic, because a typical glideslope is 3°, and intercepting from above would require sink rates that you may not be able to safely achieve without resorting to speedbrakes. The only alternative to "hold and intercept" would be a continuous descent, where the autopilot puts you on a descent path that gets you exactly to the right altitude at the glideslope interception point. The advantage of this is that it's more fuel efficient, as you glide in with the engines at a constant low setting, so you don't need to rev them up at low altitude.

Typically, the order of operations is:

1. Descend to intercept altitude (normally about 2000-3000 ft AGL)
2. Turn onto localizer intercept course (normally no more than 45 degrees off the localizer course)
3. Arm "APP" on the autopilot
4. Intercept localizer; "LOC" lateral mode engages
5. Intercept glideslope; "GS" vertical mode engages

Depending on the aircraft type you're flying, deviating from this procedure may be possible, such as intercepting the glideslope before the localizer. There may also be additional constraints: for example, some Boeing autopilots will refuse to descend below the selected altitude, and because the selected altitude is typically the intercept altitude, the aircraft will not descend any further when catching up with the glideslope; instead, once established on the intercept altitude and the autopilot in ALT HLD mode, you have to turn the altitude selection down to zero, or at least minimums. Not sure if this is the case in the 777 though.
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Re: Trouble landing 777-200LR

Postby flyer » Sun Sep 06, 2020 7:47 pm

Pancho, thank you for the url.

I have also found that much of this information is actually included in Flight Gear.
(Go to AI --> ATC Services in Range.)

I am still having some trouble with the approach contact.
I can be almost right on the glide path and approach does not want to
connect. The localizer is easier. I can make precise contact at the exact start
of the radio beacon. Yet, approach has been much more difficult. It might be
related to the conditions that are set for approach (i.e., gear down , enough flaps,
correct speed). The best approach is typically to be ~2,000 feet and just wait for
the glide slope to intercept you from above, though even this does not
always seem to work. Sometimes the pink diamond on the flight screen in front of
the yoke has been solid and went right past the zero mark without locking in.
I sometimes I have had to chase the glide slope several times before it engages,
sometimes I am almost right at the runway before Land3 shows.
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Re: Trouble landing 777-200LR

Postby flyer » Mon Sep 07, 2020 5:12 pm

I notice when landing that the pilot view of the center line is not actually "centered". The pilot is to the left of the true center line of the plane, so must adjust perspective to imagine where the center line is. Would it be helpful to redesign aircraft in order that the pilot seat is directly on the center line of the plane. This way when the pilot lands or takeoffs the center line from the pilot's perspective is actually the center line.

This is great!
In the previous comments mention was made about VREF, though I was not sure how to find it.
When I zoomed into the pilot cockpit dial it was right in front of me with a green line. The funny thing
was that this REF value was 115 in my last fly-in. I had been guessing that I needed a speed of about
170 to land.

That was way way to fast. It made landing much more difficult. At 115, it is super easy. Near touchdown
I can cut the autopilot speed to 100, and add flaps. With so much drag on the plane slowing down is not a problem.
My last touchdown speed was ~105. At such a low landing speed it is much easier to control the aircraft on the ground.
Very quickly the speed decreases to below 70 and the plane is under complete control.

Remarkable!
I can move the speed just to above VREF on landing, add in full flaps, add in full speedbrakes... all I need to do is nose down
and the plane rapidly decelerates down the center line. Before I was having problems with control on landing, with all this
braking ability landing is really easy.

It is much much easier landing near VREF. In some of my recent landings I have been touching down ~95 knots. I am below
stall speed! With these super slow landings, I am down to slow runway speeds of ~ <70 almost immediately. With full flaps
and maximum speedbraking, my landings are under very good control.
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