Takeoff Alternates

[msk2468]

Can anyone help me solidify my knowledge of this subject? My basic understanding is that you need to file a T/o alternate if you are unable to get back into the aiport of departure in the event of losing an engine due to the weather minima. I am not sure if that is exactly right and I am not quite sure of the exact requirements for the alternate.. Maybe I should already know this but I can never seem to get a completely clear answer, even from some very experienced pilots I have asked nor can I find s specific far. Thanks for any help

 

[rumpletumbler]

If I couldn't get back into my departure point I wouldn't take off. Screw the regs....it is just stupid to do so.

 

[Stifler's Mom]

Sounds about right to me. You have the legal weather minimums to depart an airport, but you don't have the weather minimums to get back in if you need to.

 

[stingray]

If the weather is below the minuimums which would allow you to attempt an approach at your departure airport, then you need to have a t/o alternate

 

[Saabslime]

As far as I can recall, the t/o alternate must not be any more than one hours flying time on one engine in still air. You are correct about needing one if the wx is below approach mins at takeoff.

 

[homerjdispatch]

If the weather at the departure airport is below landing mins a takeoff alternate must be added.

The FARS state that the takeoff alternate must be within "45 minutes of departure airport based on one engine inop (for two engine aircraft) normal cruise in still air"

 

[homerjdispatch]

saabslime beat me to it....

 

[msk2468]

thanks guys, very helpful. Homer do you have the FAR number by chance?

 

[chas]

If the weather conditions at the airport of takeoff are below the landing minimums of the certificate holder's operations specifications for that airport you cannot takeoff unless you have a alternate for takeoff.

For aircraft having two engines, if a departure alternate airport is required, it cannot br more than 1 hr. from the departure airport at normal cruising speed in still air with one engine inoperative.

For aircraft having three ot more engines, it cannot br more than 2 hr. from the departure airport at normal cruising speed in still air with one engine inoperative.

For 135, a takeoff may not be made from an airport that is below the authorized IFR landing minimums for the approach in use unless there is an alternate airport with the required IFR landing minimims within 1 hr. flying time, at normal cruise speed in still air. ( They take out the one engine inoperative requirement.)

 

[Andy Neill]

thanks guys, very helpful. Homer do you have the FAR number by chance?

135.217 and 121.617 as applicable.

 

[cvsfly]

If the weather conditions at the airport of takeoff are below the landing minimums of the certificate holder's operations specifications for that airport you cannot takeoff unless you have a alternate for takeoff.

For aircraft having two engines, if a departure alternate airport is required, it cannot br more than 1 hr. from the departure airport at normal cruising speed in still air with one engine inoperative.

For aircraft having three ot more engines, it cannot br more than 2 hr. from the departure airport at normal cruising speed in still air with one engine inoperative.

For 135, a takeoff may not be made from an airport that is below the authorized IFR landing minimums for the approach in use unless there is an alternate airport with the required IFR landing minimims within 1 hr. flying time, at normal cruise speed in still air. ( They take out the one engine inoperative requirement.)

Speaking strickly 135, the FAR reference I believe your looking for is 135.217 - no mention of 1 eng inop or # of engines. Conditions are above T/O min., but below IFR landing min. Example: KROA - wx reported 800'/1sm, wind 190/20. Departing R-15, T/O min = std = 1sm (with DP), landing R-24, app in use ILS 33 circle 24 (landing min = 1 3/4 Cat A & B, or Cat C = 2 1/4 (MDA=764')). The cause for this scenario usually are NOTAMS, the available appr (especially w/ circling app), & terrain. I believe the interpretation is even if there are working approaches to lower min. you are restricted to the available approaches in use (may have more leeway (to hang yourself) at an uncontrolled field. I believe it also has a bearing on operators approved for lower than standard T/O min. For Ops Spec C057 IFR T/O Minimums (no lower than standard) states: Standard for 2 or less = 1 sm, 1/2 sm for more than 2 eng. Condition 1 - if no T/O min is published - then use Std (TDZ RVR is controlling)
Condition 2 - if a T/O min is published - use that minimum, including any min climb gradient, etc. (TDZ RVR is controlling)
Condition 3 - when T/O min are = to or less than Std (ie 1 sm for 2 eng) - you may use a T/O min = to the lowest CAT 1 IFR LANDING min (ie if an ILS is avail, then = 200- 1/2)(again TDZ RVR is controlling)

Anyone with lower than std T/O min care to explain how 135.217 is used?

 

[atldc9]

As a 121 Carrier we run into this frequently. We have Op's SPec's that allow for takeoffs with a reported RVR as low as 600 feet. Our company's lowest landing minimums are 100'DH and 1000 RVR. If you took off at a station where the wx is 600 RVR, we would be legal to takeoff, but not be legal to turn around and come back in of we needed to. Consequently, we list a takeoff alternate to comply with 121.617.

IN order to be in compliance, we simply list a Takeoff alternate. The alternate must meet alternate weather minimums, and be within 1 hour's flying time in still air with 1 engine inop. For the 717, that is 280 nm.

 

[msk2468]

great stuff, thank you all

 

[Guitar Guy]

As previously stated in a few posts, check 121.617 and 135.217 for the pertinent FAR references.

It's interesting to note that the distance to the takeoff alternate is a function of the number of engines on the aircraft for Part 121 but is only a "1 hour" distance for Part 135. Also, Part 121 says that the distance to the alternate is to be calculated using "normal cruising speed in still air with one engine inoperative" while Part 135 simply says "at normal cruising speed, in still air". So for Part 135, there's no requirement for the 1-hour distance to be calculated with an engine inoperative.

 

[Hawker rider]

Very interesting discussion that a subject like this can start.

For instance, I fly a 747 classic. Cat3 approved, so if the weather is at cat3 minimums I can take off, well I need a take off aternate right? no problem, the regulations say that I need a take off alternate if my departure airport has not the required amount of weather for me to land again following an engine failure.

Well with only an engine failure, I will default back to catII minumums, with an autoland still possible, not really a big deal there, but what if for instance I lose one or more of my hydraulic systems? That will make me a lot more restrictive than "just" being in a one-engine-out at that time. And I know that I can have a 2-hour airport on catII basis, but if I need to fly further to find an airport on catI basis, without the use of some crucial hydraulics...

Some people didn't really think stuff like that through, but it just shows you that even though they are trying to cover a critical situaltion, it really depends on the type of airplane what your minimums should be. Thank goodness stuff doesn't always go as wrong as it does in the sim sometimes..

 

[dispatchguy]

One thing:

Anytime I dispatch a flight using lower than standard takeoff mins, I always add a takeoff alternate.

For those who fly in mountainous terrain under 121 with twin engine aircraft, if you declare a takeoff alternate, you should also insure that your takeoff weight has been limited to that which would allow terrain clearance (121.191A1) from the origin airport to takeoff alternate. About a year ago, a major legacy airline who flies B737-300s out of KDEN, just figured out that a fully-loaded B737-300, with GJT as your takeoff alternate, will not clear the terrain west of Denver at all; especially when fully loaded, and issued an ops bulletin that their dispatchers may no longer use GJT as a takeoff alternate for DEN for the B737...

Their antiquated and outdated flight planning system was unable to crunch the numbers to verify compliance with 121.191; their state of mind was "if its within the range, its legal to launch..."

 

[mike1mc]

Maybe this is an ignorant question, but where to you "file" the takeoff alternate. Do you file it like you would an arrival alternate? What if weather requires an alternate at your destiantion? Remarks section?

 

[dispatchguy]

For a 121 operation, your release could look like this:

ORG TOA DST AL1 AL2
ORD MKE PHX ONT LAS

From ORD-PHX, with MKE as your takeoff alternate for ORD, with LAS and ONT as your alternates for LAS.

Its just on your flight release for 121 operations; there is no block for it on your FAA ATC-filed flight plan

 

[mike1mc]

Its just on your flight release for 121 operations; there is no block for it on your FAA ATC-filed flight plan

What about for 135 ops? I know there is no block for it, but do you file it as part of your flight plan or just list it in the remarks section?

 

[NoMMO]

We're a Part 91 Corporate jet operator. We just adopted Take-off alternate requirements for IS-BAO Certification.