Do not understand derived alternate minimums in relation to exemption 17347

[KeepinItLegal]

Don’t know why, but I’m not picking up on this exemption and relationship to derived alternate minimums. Wondering if someone can explain this to me.

Thanks!

 

[Delta Echo]

Exemption 17347 reads like Exemption 3585 for the regional airlines.

Dest. for ETA contains tempo for ETA with no less than half required vis mins.

1st Alt contains tempo with no less than half vis/cigs based on derived alt mins.

2nd Alt Main body stays at or above required vis/cig mins based on derived alt mins.

Dest and 1st alt Main body must not be less than respective landing min and alt mins.

 

[RORO]

Don’t know why, but I’m not picking up on this exemption and relationship to derived alternate minimums. Wondering if someone can explain this to me.

Thanks!

It's actually quite simple, just think of it in terms of risk mitigation.

Any time you hear the word "exemption", understand that it is an EXEMPTION to an FAR, I.E., we will be breaking an FAR but it's ok because the FAA has allowed us to do so under these very specific circumstances.

In the case of exemption 17347, we are going to dispatch to an airport with weather WORSE than what we need to get in, but its probably temporary in nature and won't affect us. If it does affect us, we have layered our risk so that we always have a usable alternate.

Our destination must meet approach mins, and this exemption allows us to dispatch as long as the conditional statement(which is temporary in nature) is no less than half of that value.

It would be a little tight to hold the 1st alternate to the same standard, and alternates are bound by C055 (derived minima) anyways, so we are gonna allow dispatch if the main body meets derived minimums and the conditional statement meets half of that.

Now, lets say this temporary situation is actually a really big issue. We don't want the plane to be in the air with nowhere to land because the weather is too bad. For that case, we're gonna require a second alternate to use exemption 17347, but there is no reduced minimums for dispatch for the second alternate. Worst case scenario, this airport had a forecast above derived minimums in all scenarios so there was an exit strategy.

It's just allowing you to break the rules on normal dispatch philosophy by limiting how bad the weather can get, and requiring it to be temporary as well as retaining an alternate that meets normal dispatch standards (C055)

 

[MacJohn92]

It's actually quite simple, just think of it in terms of risk mitigation.

Any time you hear the word "exemption", understand that it is an EXEMPTION to an FAR, I.E., we will be breaking an FAR but it's ok because the FAA has allowed us to do so under these very specific circumstances.

In the case of exemption 17347, we are going to dispatch to an airport with weather WORSE than what we need to get in, but its probably temporary in nature and won't affect us. If it does affect us, we have layered our risk so that we always have a usable alternate.

Our destination must meet approach mins, and this exemption allows us to dispatch as long as the conditional statement(which is temporary in nature) is no less than half of that value.

It would be a little tight to hold the 1st alternate to the same standard, and alternates are bound by C055 (derived minima) anyways, so we are gonna allow dispatch if the main body meets derived minimums and the conditional statement meets half of that.

Now, lets say this temporary situation is actually a really big issue. We don't want the plane to be in the air with nowhere to land because the weather is too bad. For that case, we're gonna require a second alternate to use exemption 17347, but there is no reduced minimums for dispatch for the second alternate. Worst case scenario, this airport had a forecast above derived minimums in all scenarios so there was an exit strategy.

It's just allowing you to break the rules on normal dispatch philosophy by limiting how bad the weather can get, and requiring it to be temporary as well as retaining an alternate that meets normal dispatch standards (C055)

So 17347 is based on a solid second alternate. The second alternate is our go-to plan when plan A (the destination) and plan B (the first alternate) both fail.

 

[///AMG]

My understanding is that this was won in court, during deregulation, to prevent smaller carriers without access to in-house weather guessers (and thus reliant on the CYA weather service forecasts), from losing revenue compared to the majors who typically did have access to more accurate reporting. The implications of TEMPO can vary widely depending on the forecaster. As an example, US Navy fields, especially in the Southeast and East coast, routinely write infinite TEMPO lines if there is even the most remote possibility of bad weather. Worst case lines that never come to fruition. But they aren't gonna be to blame, if something bad happens. Is this the exemption we're talking about? Think it got a re-name a year or so ago, right?

 

[guywhoflies]

My understanding is that this was won in court, during deregulation, to prevent smaller carriers without access to in-house weather guessers (and thus reliant on the CYA weather service forecasts), from losing revenue compared to the majors who typically did have access to more accurate reporting. The implications of TEMPO can vary widely depending on the forecaster. As an example, US Navy fields, especially in the Southeast and East coast, routinely write infinite TEMPO lines if there is even the most remote possibility of bad weather. Worst case lines that never come to fruition. But they aren't gonna be to blame, if something bad happens. Is this the exemption we're talking about? Think it got a re-name a year or so ago, right?

#thankspeopleexpress

 

[gopherdx]

My understanding is that this was won in court, during deregulation, to prevent smaller carriers without access to in-house weather guessers (and thus reliant on the CYA weather service forecasts), from losing revenue compared to the majors who typically did have access to more accurate reporting. The implications of TEMPO can vary widely depending on the forecaster. As an example, US Navy fields, especially in the Southeast and East coast, routinely write infinite TEMPO lines if there is even the most remote possibility of bad weather. Worst case lines that never come to fruition. But they aren't gonna be to blame, if something bad happens. Is this the exemption we're talking about? Think it got a re-name a year or so ago, right?

Ours went from 3585 to 20108. Why? Who knows.

 

[LetsGoMorty]

Hmmm...Not sure what your questions is Sweetheart. You can derive alternate airport minimums all day and night and it not have a thing to do with ANY exemption. There's that. Deriving Alt Mins is a single and separate skill. So dont conflate it with other •tte.
The exemption regarding bad wx go-no-go, whatever number you use, really is not about deriving alt mins. Sure you need to know how to do it, but the exemptions are about reading the TAF carefully and planning a 2nd Alternate as needed. Good luck and like they say,"dont over think it"

 

[DaWolf85]

My understanding is that this was won in court, during deregulation, to prevent smaller carriers without access to in-house weather guessers (and thus reliant on the CYA weather service forecasts), from losing revenue compared to the majors who typically did have access to more accurate reporting. The implications of TEMPO can vary widely depending on the forecaster. As an example, US Navy fields, especially in the Southeast and East coast, routinely write infinite TEMPO lines if there is even the most remote possibility of bad weather. Worst case lines that never come to fruition. But they aren't gonna be to blame, if something bad happens. Is this the exemption we're talking about? Think it got a re-name a year or so ago, right?

It used to be 3585. The name is now different for every carrier, I believe. That way the FAA can tell where you work when you post about it

 

[///AMG]

It used to be 3585. The name is now different for every carrier, I believe. That way the FAA can tell where you work when you post about it

Yeah that checks out. I only learned of the new exemption number when my shop officially dropped ours. Not sure why, I guess it wasn't particularly useful for our operation maybe?