Question - how do you calculate part 77?
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RussR
En-Route
Need a bit more information on what you're asking. Why is what calculated from the physical end of the runway (there are several surfaces shown in that graphic), and why do you think they shouldn't be?
Im sorry, i was in a hurry and im still in process of learning about it
Primary Surface: A surface longitudinally centered on a runway. When the runway has a specially prepared hard surface, the primary surface extends 200 feet beyond either end of the that runway; but when the runway has no specially prepared surface, or planned hard surface, the primary surface ends at the physical ends of the runway.
From my understanding if part 77 starts at the end of primary surface - did they added extra 200ft? here is how runway looks like
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luvflyin
Touchdown! Greaser!
Im sorry, i was in a hurry and im still in process of learning about it
Primary Surface: A surface longitudinally centered on a runway. When the runway has a specially prepared hard surface, the primary surface extends 200 feet beyond either end of the that runway; but when the runway has no specially prepared surface, or planned hard surface, the primary surface ends at the physical ends of the runway.
From my understanding if part 77 starts at the end of primary surface - did they added extra 200ft? here is how runway looks like
Here’s what seems kinda like a Cliff Notes version. Maybe it will help
https://wsdot.wa.gov/sites/default/files/2006/12/13/aviation-far-part-77-basics.pdf
murphey
Touchdown! Greaser!
Part 77
FAR Part 77 allows the “FAA to identify potential. aeronautical hazards in advance thus preventing or. minimizing the adverse impacts to the safe and efficient. use of navigable airspace”Dec 13, 2006
What exam is your question relating to? I don’t remember anything like it on Private, Instrument, BGI or AGI. Or are you just interested in how the FAA does things relating to airports? Or about to enter a law suit against the airport?
FAR Part 77 allows the “FAA to identify potential. aeronautical hazards in advance thus preventing or. minimizing the adverse impacts to the safe and efficient. use of navigable airspace”Dec 13, 2006
What exam is your question relating to? I don’t remember anything like it on Private, Instrument, BGI or AGI. Or are you just interested in how the FAA does things relating to airports? Or about to enter a law suit against the airport?
If its counted 200ft from end of runway it gives our trees 10 more ft to grow versus being calculated from physical end of pavement -i like nature, i like our trees and i have bluebirds nest on one of them so its personal
I think you have it backwards... it's a hard surface runway (as opposed to a turf or dirt runway), so the primary surface extends 200' past the end of the runway, as if the runway was 200' longer (on each end) than the actual pavement, so your trees have less room to grow than they would if there was no 200' extension.
RussR
En-Route
If its counted 200ft from end of runway it gives our trees 10 more ft to grow versus being calculated from physical end of pavement -i like nature, i like our trees and i have bluebirds nest on one of them so its personal
Okay, I understand. You're a resident living near an airport. In that case, I'd say this is probably not the best forum to answer your question - this is a forum for pilots primarily, and honestly we generally don't know about airport clearance surfaces. You're looking for an airport manager-type person, or an airport design consultant (of which there are many out there, it's a whole career field). I don't know of any specific sites to refer you to, but a Google search for something like "airport design consultant" might be helpful.
The end of the pavement.Thank you
Thats what im confused about - where is end of runway in this case?
luvflyin
Touchdown! Greaser!
Im sorry, i was in a hurry and im still in process of learning about it
Primary Surface: A surface longitudinally centered on a runway. When the runway has a specially prepared hard surface, the primary surface extends 200 feet beyond either end of the that runway; but when the runway has no specially prepared surface, or planned hard surface, the primary surface ends at the physical ends of the runway.
From my understanding if part 77 starts at the end of primary surface - did they added extra 200ft? here is how runway looks like
The displaced threshold may work in your favor. Found this:
"Runway Displaced Thresholds• Sometimes is not possible to comply with all FAR 77 criteria (specially the five imaginary surfaces)• Runway displaced thresholds have to be defined to meet the criteria."
I'm assuming they've already done the study there and that's why there is a displaced threshold. That could make it the point from which the angles and heights are calculated.
luvflyin
Touchdown! Greaser!
thank you everyone
dtuuri
Final Approach
If you're happy, we're happy!
luvflyin
Touchdown! Greaser!
How’d all this start anyway? Did you get some kind of notice that you may have to cut your trees someday
Tarheelpilot
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Tarheelpilot
Man it sure would suck if an airplane hit the tree with the blue bird nest. But screw it. Blue birds and trees are more important than peoples lives.
We have to decide within next couple of days do we sell airspace, and with how they recalculated its much lower then previous easement that exists in the same subversion - Hight of airspace will start as low as 24.5 and up to about 30 where all the trees are - where the bluebird tree is as well. 29 ft. over house. Easement states we either let them remove all trees or let them mark as obstacles and we will be responsible for life to remove them and trim them in the future to the heights of part 77.
if it would be calculated including displaced threshold the lowest point would be about 36.5 ft -42 ft where the trees are (county zoning is 40 ft ) that would mean some trees will stay and we don't have to trim them until they are 36-40 ft.
Also that's how they worded what RPZ is in easement and i don't know if its me or these are two different things in one sentence
As used herein, the term “Runway Protection Zone, or RPZ” shall mean a trapezoidal zone
beginning 200 ft outboard of the landing threshold with an inner width of 250 ft, an outer width of
450 ft, and a length of 1,000 ft for the Approach RPZ; and shall mean a trapezoidal zone beginning
200 ft outboard of the physical end of the pavement, if not collocated with the landing threshold, with
an inner width of 250 ft, an outer width of 450 ft, and a length of 1,000 ft for the Departure RPZ.
Meet the trees:
if it would be calculated including displaced threshold the lowest point would be about 36.5 ft -42 ft where the trees are (county zoning is 40 ft ) that would mean some trees will stay and we don't have to trim them until they are 36-40 ft.
Also that's how they worded what RPZ is in easement and i don't know if its me or these are two different things in one sentence
As used herein, the term “Runway Protection Zone, or RPZ” shall mean a trapezoidal zone
beginning 200 ft outboard of the landing threshold with an inner width of 250 ft, an outer width of
450 ft, and a length of 1,000 ft for the Approach RPZ; and shall mean a trapezoidal zone beginning
200 ft outboard of the physical end of the pavement, if not collocated with the landing threshold, with
an inner width of 250 ft, an outer width of 450 ft, and a length of 1,000 ft for the Departure RPZ.
Meet the trees:
Tarheelpilot
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It’s not possible to meet a tree.
luvflyin
Touchdown! Greaser!
We have to decide within next couple of days do we sell airspace, and with how they recalculated its much lower then previous easement that exists in the same subversion - Hight of airspace will start as low as 24.5 and up to about 30 where all the trees are - where the bluebird tree is as well. 29 ft. over house. Easement states we either let them remove all trees or let them mark as obstacles and we will be responsible for life to remove them and trim them in the future to the heights of part 77.
if it would be calculated including displaced threshold the lowest point would be about 36.5 ft -42 ft where the trees are (county zoning is 40 ft ) that would mean some trees will stay and we don't have to trim them until they are 36-40 ft.
Also that's how they worded what RPZ is in easement and i don't know if its me or these are two different things in one sentence
As used herein, the term “Runway Protection Zone, or RPZ” shall mean a trapezoidal zone
beginning 200 ft outboard of the landing threshold with an inner width of 250 ft, an outer width of
450 ft, and a length of 1,000 ft for the Approach RPZ; and shall mean a trapezoidal zone beginning
200 ft outboard of the physical end of the pavement, if not collocated with the landing threshold, with
an inner width of 250 ft, an outer width of 450 ft, and a length of 1,000 ft for the Departure RPZ.
Meet the trees:
Who’s we? Are your neighbors affected to? Is it a Homeowners Association? What may be happening is they are doing an obstruction survey so that Instrument Approaches to the airport can be flown at night. All of the Approaches to Smith Field are currently not authorized at night. Based on some of the things you found, it seems like maybe the displaced threshold card could be played.
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RussR
En-Route
Again, if the trees are important to you, you need to hire an airport design consultant, not rely on the opinions of all of us here on the board.
luvflyin
Touchdown! Greaser!
https://www.kimley-horn.com/service/aviation-consulting/airport-design/
Yeah. @etnako , here’s one with an office in Indianapolis. But while we’re here Russ, does the paved surface before the threshold have to be considered when building the Approach. Of course it has to be considered. What I’m getting at is if there are obstructions in the way, can a displaced threshold be created, and then calculations are done from that point?
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RussR
En-Route
Generally any pavement before the charted runway threshold is irrelevant for procedure design. There are a few considerations there, but overall they're minor. Procedures are built to the landing threshold, whether that's displaced or not.
If there are obstacle issues, then yes a displaced threshold can be created. That's one of the main reasons for a displaced threshold in the first place. But that's something that generally happens well before the actual procedure design work.
aterpster
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aterpster
KSAN Runway 27.
luvflyin
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Yeah. Ain't no way they're calculating anything from the pavement end there. Can you spell 'blast fence' boys and girls
. Whadda ya know about this RPZ stuff?
aterpster
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aterpster
We used it for takeoff performance.Yeah. Ain't no way they're calculating anything from the pavement end there. Can you spell 'blast fence' boys and girls
luvflyin
Touchdown! Greaser!
So would ya line up, throw out the reversers, back up until ya felt a little nudge, and then go
aterpster
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aterpster
Your humor is lost on me. Taxiway B1 to turn onto Runway 27 almost at the physical end.So would ya line up, throw out the reversers, back up until ya felt a little nudge, and then go
luvflyin
Touchdown! Greaser!
We were talking about Runway Protection Zones. Whether it should be calculated from the end of any pavement or the Runway Threshold, particularly a Dislplaced Threshold. And it led to TERPing Instrument Approaches. They are done from the Threshold. Obstructions are considered relative to a ‘plane’ that starts at the Threshold, not the end of pavement. You offered up KSAN RW 27 as an example. I said yeah, you couldn’t calculate anything from there, meaning Approaches. The blast fence itself sits on the pavement at the end of the Rumway. When you brought up departures I thought you were kinda kidding. But yeah, the RPZ at the other end is pertinent to departures. So I had a silly vision of backing up to the fence to get every inch you can.
aterpster
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In the last century I flew the 727, 767, and 1011 in and out of that airport. Many things have changed since then, but not the runway or how to enter Runway 27 for takeoff.
Didn't look in here for a few and i am very thankful for all your opinions on the subject.
I did brought up part 77 calculation to airport director and he said he will look into giving me answer on how was that calculated - so far nothing.
Since than i am still reading into it in case the answer will be that new survey is covering the airspace for future adjustment of threshold to the beginning of the pavement.
So far i found If it moves more than 200 ft it needs to be approved and environmental study needs to be done, especially having residential area so close to landing threshold.
Also if you calculate part 77 to remove trees that will allow to move the threshold to that part 77 to be calculated this way its a bit of a catch 22 for me... and want to make sure it can be done this way.
I will post here when they will get back to me.
I did brought up part 77 calculation to airport director and he said he will look into giving me answer on how was that calculated - so far nothing.
Since than i am still reading into it in case the answer will be that new survey is covering the airspace for future adjustment of threshold to the beginning of the pavement.
So far i found If it moves more than 200 ft it needs to be approved and environmental study needs to be done, especially having residential area so close to landing threshold.
Also if you calculate part 77 to remove trees that will allow to move the threshold to that part 77 to be calculated this way its a bit of a catch 22 for me... and want to make sure it can be done this way.
I will post here when they will get back to me.
RussR
En-Route
You asked the airport director about it? While that's okay as a secondary research avenue or initial fact-finding, I have to envision a certain conflict of interest here. Typically, homeowners and airport managers are on opposite sides of any airport expansion-type project. You wouldn't ask a car dealer if you should keep your old car or buy a new one...
And this can get into some fairly complicated areas. Self-research is only good up to a point, after that you really need to talk to someone who works in this area every day (like the company linked above, or others).
I reached out to the company today, and waiting for them to respond.
I received following answer from the airport about part 77 "the approach surface is based on a 20:1 slope that begins 200 ft outboard of the physical end of pavement. Part 77 does not consider displaced thresholds in its siting of the Approach Surface. With the 200 ft difference in the Type 4 and Part 77 Approach Surface starting points, a 10 ft difference between the two is achieved inherently. If obstructions cannot be mitigated, they are typically lit (obstruction lights) "
I received following answer from the airport about part 77 "the approach surface is based on a 20:1 slope that begins 200 ft outboard of the physical end of pavement. Part 77 does not consider displaced thresholds in its siting of the Approach Surface. With the 200 ft difference in the Type 4 and Part 77 Approach Surface starting points, a 10 ft difference between the two is achieved inherently. If obstructions cannot be mitigated, they are typically lit (obstruction lights) "