Hello, thank you for this! Very helpful. The reg 121.617 mentions “below the landing minimums” - does this include ceiling and vis / or vis only just like a normal approach requirement? On the other hand, how do they choose the IAP at departure airport chosen to know if below landing mins or not at departure airport?
You are welcome! So 121.617 has always been interpreted as only visibility. This is true unless the approach has a ceiling requirement (for the selected approach) which essentially is never a requirement in the United States...but it could be a requirement in another country. They choose a suitable IAP at the airport that is one that favors wind and has the lowest possible minimums typically. I hope this answers your question! (and check out the newer version I made of this video please...I think it is a lot better!)
There are a few ways to answer this. For an approach, you look at the visibility requirement printed on the bottom of the approach chart. (See my Jeppesen chart overview for more.) Related to alternates, when using Operations Specification C055 to derive alternate minimums, you have to look at the specific approach or approaches you are planning for that alternate. This video was about takeoff minimums, not approach minimums. But, here are some links to other helpful videos: ruclips.net/video/W-zceRBRZEY/видео.html ruclips.net/video/e0hzIQTQmJQ/видео.html ruclips.net/video/foDoi7HJgRc/видео.html
Visibility is controlling under 91.175(f) for operations under 121 and 135 (and other parts). However, many of these operators also have Operations Specifications (ops specs) that allow for "lower than standard" takeoff minimums. I explain that a lot more in another video on Part 121 Takeoff Minimums. In this example, the flight could take off but under 91.175(d)(2) it could not return to land in the event of an urgent need to return.
Hello! If you need a takeoff alternate, and the air carrier has the Ops Spec for derived alternate minimums, then you would use those derived alternate minimums for the takeoff alternate. I have a video about derived alternate minimums as well that might be helpful!
It is a generic number that we used for the Boeing 737-300 based on one engine inop in still air. Each airline will have a predetermined distance for each type in its fleet.
@@LauraLaster747 Many Thanks For the video. My doubt regarding calculation of this TO Altn distance is that do we need to consider CLB,CRZ,DSC segments ?
@@jinssebastian6755 Typically an airline or operator selects a distance specifying the radius in which the takeoff alternate must fit. This number has been pre-calculated by the operator or airline and accounts for climb, cruise, descent and typical aircraft speeds. Since the takeoff alternate is a planning airport only - if something really goes wrong in flight, the crew can decide to go anywhere they deem necessary and safe - it isn't planned out with the climb, cruise, descent segments.
A clear explanation, we appreciate your efforts.
Excellent! I am glad I could help.
Thanks Laura, appreciate your help on this subject.
So glad it was helpful to you! What other topics would you like to see?
Hello, thank you for this! Very helpful. The reg 121.617 mentions “below the landing minimums” - does this include ceiling and vis / or vis only just like a normal approach requirement? On the other hand, how do they choose the IAP at departure airport chosen to know if below landing mins or not at departure airport?
You are welcome! So 121.617 has always been interpreted as only visibility. This is true unless the approach has a ceiling requirement (for the selected approach) which essentially is never a requirement in the United States...but it could be a requirement in another country. They choose a suitable IAP at the airport that is one that favors wind and has the lowest possible minimums typically. I hope this answers your question! (and check out the newer version I made of this video please...I think it is a lot better!)
thanks for this video for clearing the concept.
You are welcome!!
Is there a specific approach you were using to determine approach minimums?
There are a few ways to answer this. For an approach, you look at the visibility requirement printed on the bottom of the approach chart. (See my Jeppesen chart overview for more.) Related to alternates, when using Operations Specification C055 to derive alternate minimums, you have to look at the specific approach or approaches you are planning for that alternate. This video was about takeoff minimums, not approach minimums. But, here are some links to other helpful videos:
ruclips.net/video/W-zceRBRZEY/видео.html
ruclips.net/video/e0hzIQTQmJQ/видео.html
ruclips.net/video/foDoi7HJgRc/видео.html
Thanks for laying it all out. I have been struggling with minimums because of how it was initially explained to me. Now I get it! 😁😁😁
SO glad you learned from the video!!
Thanks a lot
Hello! You are welcome! Thank you for watching!
thank you
You're welcome!
The reason why Vis is controlling.. is because 91.175?
Visibility is controlling under 91.175(f) for operations under 121 and 135 (and other parts). However, many of these operators also have Operations Specifications (ops specs) that allow for "lower than standard" takeoff minimums. I explain that a lot more in another video on Part 121 Takeoff Minimums. In this example, the flight could take off but under 91.175(d)(2) it could not return to land in the event of an urgent need to return.
I’m assuming the weather minimums for these TO alternates are the same standard alternate 121 mins?
Hello! If you need a takeoff alternate, and the air carrier has the Ops Spec for derived alternate minimums, then you would use those derived alternate minimums for the takeoff alternate. I have a video about derived alternate minimums as well that might be helpful!
Something about her voice sounding like Louise belcher is soothing
I am hoping this is some kind of compliment??? 🤣🤣
Thanks, just wondering where you got the 300 miles rule from ? Can’t find it anywhere on the reg
It is a generic number that we used for the Boeing 737-300 based on one engine inop in still air. Each airline will have a predetermined distance for each type in its fleet.
@@LauraLaster747 Many Thanks For the video. My doubt regarding calculation of this TO Altn distance is that do we need to consider CLB,CRZ,DSC segments ?
@@jinssebastian6755 Typically an airline or operator selects a distance specifying the radius in which the takeoff alternate must fit. This number has been pre-calculated by the operator or airline and accounts for climb, cruise, descent and typical aircraft speeds. Since the takeoff alternate is a planning airport only - if something really goes wrong in flight, the crew can decide to go anywhere they deem necessary and safe - it isn't planned out with the climb, cruise, descent segments.
@@LauraLaster747 Thanks a lot
thank you
You are welcome!