B777 visual segment
Thread Starter
B777 visual segment
Hello,
I am currently working on my 777 type rating and I am wondering about the B777 cutoff angle.
For two reasons : how to evaluate the visual segment in an LVO takeoff ? Usually, we will count the number of lights available and multiply the number of visible light intervals by its 15m length. But then we need to add the cockpit cutoff distance. What is the cockpit cutoff distance on this plane ?
Then, about the landing phase, when we follow a PAPI, the main gear is bound to hit the ground, without flare, at around 100-130m after threshold.
So the problem is more often short landing than long landing. But if you do manage to perform a doubtfully long landing, how can you evaluate ?
From the sim sessions we've done, it seems like when we see the xxxm meter marks disappear and touchdown right at this moment, the touchdown distance is approximately 100-150 (??) meters before the mark.
What is the value of the cutoff angle ? What is the cutoff distance if we have the main gear on ground, 5° of pitch ?
The formula is rather easy, take the pilot eye height on ground, add pitch angle (rad) * distance from pilot to main gear, to find the eye height.
Then complete a triangle with this height, and the cutoff angle minus the chosen pitch angle. This will give a good idea on how to evaluate landing distance.
I just lack the cutoff angle.
Thanks
I am currently working on my 777 type rating and I am wondering about the B777 cutoff angle.
For two reasons : how to evaluate the visual segment in an LVO takeoff ? Usually, we will count the number of lights available and multiply the number of visible light intervals by its 15m length. But then we need to add the cockpit cutoff distance. What is the cockpit cutoff distance on this plane ?
Then, about the landing phase, when we follow a PAPI, the main gear is bound to hit the ground, without flare, at around 100-130m after threshold.
So the problem is more often short landing than long landing. But if you do manage to perform a doubtfully long landing, how can you evaluate ?
From the sim sessions we've done, it seems like when we see the xxxm meter marks disappear and touchdown right at this moment, the touchdown distance is approximately 100-150 (??) meters before the mark.
What is the value of the cutoff angle ? What is the cutoff distance if we have the main gear on ground, 5° of pitch ?
The formula is rather easy, take the pilot eye height on ground, add pitch angle (rad) * distance from pilot to main gear, to find the eye height.
Then complete a triangle with this height, and the cutoff angle minus the chosen pitch angle. This will give a good idea on how to evaluate landing distance.
I just lack the cutoff angle.
Thanks
Join Date: Mar 2006
Location: USA
Posts: 2,527
Likes: 0
Received 0 Likes
on
0 Posts
I don’t have them on hand right now, but I’m almost certain the diagram you’re looking for is in the FCTM. It may also be available in the airport characteristics document (I think that’s the name), which is publicly available.
Thread Starter
https://www.boeing.com/content/dam/b...r_3.pdf#page63
I didn't find it in the FCOM but this document indeed contained very relevant information.
Page 63, 5.9 meters.
Hence I computed 15.4 meters.
Then upon landing : (5.9+5/57.3*34.85)/tan(16/57.3) = 31.2 meters.
It's a bit disappointing. It doesn't explain why we think we landed much further than we actually did.
I didn't find it in the FCOM but this document indeed contained very relevant information.
Page 63, 5.9 meters.
Hence I computed 15.4 meters.
Then upon landing : (5.9+5/57.3*34.85)/tan(16/57.3) = 31.2 meters.
It's a bit disappointing. It doesn't explain why we think we landed much further than we actually did.
Join Date: Mar 2009
Location: Seattle, WA
Posts: 26
Likes: 0
Received 0 Likes
on
0 Posts
https://www.boeing.com/content/dam/b...r_3.pdf#page63
I didn't find it in the FCOM but this document indeed contained very relevant information.
Page 63, 5.9 meters.
Hence I computed 15.4 meters.
Then upon landing : (5.9+5/57.3*34.85)/tan(16/57.3) = 31.2 meters.
It's a bit disappointing. It doesn't explain why we think we landed much further than we actually did.
I didn't find it in the FCOM but this document indeed contained very relevant information.
Page 63, 5.9 meters.
Hence I computed 15.4 meters.
Then upon landing : (5.9+5/57.3*34.85)/tan(16/57.3) = 31.2 meters.
It's a bit disappointing. It doesn't explain why we think we landed much further than we actually did.
Take a look here (attached document)
Thread Starter
Here is the equivalent of what I am looking for :
The eye height at threshold for different types of short final guidance (PAPI, VASI, ILS..) was relevant to this discussion but not enough.
By the way, 15/tan(20°) = 41ft
The eye height at threshold for different types of short final guidance (PAPI, VASI, ILS..) was relevant to this discussion but not enough.
By the way, 15/tan(20°) = 41ft
Join Date: Jun 2014
Location: Mordor
Posts: 337
Likes: 0
Received 0 Likes
on
0 Posts
I’m unable to upload a picture for some reason, but the cutoff angle for the 777 is actually 21 degrees and the obscured segment is 15.4m. It can be found in this publication:
https://www.boeing.com/content/dam/boeing/boeingdotcom/commercial/airports/acaps/777_2lr_3er_f.pdf
Having said that, I concur with what other posters said above. It’s the manufacturer’s and operator’s job to ensure the plane is capable of performing LVTO and/or aprroaches to applicable mima.
and no, you don’t need you count centerline lights to assure 90m visual segment for LVTO. It’s a common misconception. The requirement is just that the airplane geometry allows for 90m visual segment (think an LVTO in Concorde or a DC-3
). It’s not the pilot’s job to evaluate it.
as for landing geometry, it’s all in the FCTM
https://www.boeing.com/content/dam/boeing/boeingdotcom/commercial/airports/acaps/777_2lr_3er_f.pdf
Having said that, I concur with what other posters said above. It’s the manufacturer’s and operator’s job to ensure the plane is capable of performing LVTO and/or aprroaches to applicable mima.
and no, you don’t need you count centerline lights to assure 90m visual segment for LVTO. It’s a common misconception. The requirement is just that the airplane geometry allows for 90m visual segment (think an LVTO in Concorde or a DC-3
). It’s not the pilot’s job to evaluate it.as for landing geometry, it’s all in the FCTM
Last edited by Sidestick_n_Rudder; 1st May 2024 at 18:03.
Do not overthink this, you don’t have time for it in the real airplane.
You land within the specified touchdown zone.
You can be a little early and you can be a little late, no two landings are the same.
You never cross the same river twice - Confucius
You never land short in a big jet, when it looks like you’ll overshoot the designated touchdown zone then (in the sim) a go-around is warranted.
For an FAA type ride that’s a FAIL/PASS item.
You land within the specified touchdown zone.
You can be a little early and you can be a little late, no two landings are the same.
You never cross the same river twice - Confucius
You never land short in a big jet, when it looks like you’ll overshoot the designated touchdown zone then (in the sim) a go-around is warranted.
For an FAA type ride that’s a FAIL/PASS item.
Thread Starter
I'm just very surprised at the landing distance figures that we're given. Sometimes I feel like I landed at 650-700m, and the SFI will tell I landed at 450m.
This didn't happen on my previous, medium haul, type. I was able to evaluate more precisely my landing distance.
The cuttoff angle doesn't seem to explain it.
This didn't happen on my previous, medium haul, type. I was able to evaluate more precisely my landing distance.
The cuttoff angle doesn't seem to explain it.
Stop fussing over details and look at the bigger picture.
Follow the cadence of the RA 50-40-30
Looking at your posting history you have a habit of going into the minutiae.
Here’s a simple test (and a question) for you:
The question is do you ever reach zero?
.
.
.
.
.
Follow the cadence of the RA 50-40-30
Looking at your posting history you have a habit of going into the minutiae.
Here’s a simple test (and a question) for you:
- Pick a number, any number small or large
- Divide this number by two and continue doing this.
The question is do you ever reach zero?
.
.
.
.
.
Join Date: Mar 2006
Location: USA
Posts: 2,527
Likes: 0
Received 0 Likes
on
0 Posts
I'm just very surprised at the landing distance figures that we're given. Sometimes I feel like I landed at 650-700m, and the SFI will tell I landed at 450m.
This didn't happen on my previous, medium haul, type. I was able to evaluate more precisely my landing distance.
The cuttoff angle doesn't seem to explain it.
This didn't happen on my previous, medium haul, type. I was able to evaluate more precisely my landing distance.
The cuttoff angle doesn't seem to explain it.
Join Date: Jun 2014
Location: Village of Santo Poco
Posts: 876
Likes: 0
Received 0 Likes
on
0 Posts
Join Date: Mar 2006
Location: USA
Posts: 2,527
Likes: 0
Received 0 Likes
on
0 Posts
Sorry. Unfamiliar with that terminology on this side of the ocean.
OP, don’t worry too much about landing the simulator. The airplane doesn’t handle like the simulator. On top of that, your depth perception etc will be off. Just aim for somewhere roughly in the touchdown zone, and that’ll be good enough for the simulator.
OP, don’t worry too much about landing the simulator. The airplane doesn’t handle like the simulator. On top of that, your depth perception etc will be off. Just aim for somewhere roughly in the touchdown zone, and that’ll be good enough for the simulator.