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I know all about the takeoff mins for part 91, 1 mile for 2 or less engines...blah blah blah. Anyway my question is, What happens when an airport has an alternate takeoff min.? Such as:
WENATCHEE, WA
PANGBORN MEMORIAL
TAKE-OFF MINIMUMS:
Rwy 7, NA. Rwy 12, 1500-2 or std. with a min. climb of 510' per NM to 2900.
Rwys 25, 30
, CAT A,B 1600-2 or std. with a min. climb of
360' per NM to 3100. CAT C,D 5500-3 or std. with a
min. climb of 570' per NM to 7200.
dealing with the bold part, why would they post this 1500-2 when you only need 1 mile vis. to depart anyways? is this their recommendation for safety reasons or what?
Position: Piston/Turbine Props....not just for boats!
Posts: 1,834
1 word. Obstacles
If you can't meet certain climbout performance figures, you have to use the alternate minimums. So with a 510'/nm climb rate to 2900MSL(not sure the AGL). So if you're flying a jet/t-prop, you need a climb rate of at least 1100fpm from rotation(figure 120kt initial climb segment). In a typical single engine, you would need about 700fpm @ 75kts. So if you're heavily loaded 172 and a hot day, guess what, no go! Remember, that climb rate must be sustainable all the way to that published altitude. So your non-turbocharged planes could have difficulty to some of the upper altitudes.
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i realize the obstacles part and the certain climbout requirements. My question is what is the value of trying to meet 1500 ft. ceilings and 2 miles vis. when you can do the std 1 mile.
Ok this just popped into my head. Is it stating that if you meet 1500-2 that you only have to meet the general 500ft/min climb and then when it is below that, say 1000-1, you must meet that obstacle departure climb?
I hope that makes sense about what I just tried to say.
Standard climb gradient is 200 ft/nm, not 500fpm. Part 91 does not have takeoff minimums. They are there for Part 135 and 121 Operators. Part 91 can takeoff in Zero visibility.
What those takeoff minimums are saying is if you can maintain a gradient of 510'/nm until 2900, then you can go ahead and use the standard takeoff minimums (1 mile with 2 or less engines, 1/2 mile with more than 2 engines). If you won't be able to do that (you'll have to do some research for your airplane), then you need the 1500' ceiling and 2 miles visibility if you want to takeoff from that runway.
Standard climb gradient is 200 ft/nm, not 500fpm. Part 91 does not have takeoff minimums. They are there for Part 135 and 121 Operators. Part 91 can takeoff in Zero visibility.
What those takeoff minimums are saying is if you can maintain a gradient of 510'/nm until 2900, then you can go ahead and use the standard takeoff minimums (1 mile with 2 or less engines, 1/2 mile with more than 2 engines). If you won't be able to do that (you'll have to do some research for your airplane), then you need the 1500' ceiling and 2 miles visibility if you want to takeoff from that runway.
Please correct me if I'm wrong.
ah yes, wow i can tell i was up way too early this morning. Thank you for correcting me there twice . It all makes sense now, thank you very much.
The 1500/2 is in lieu of meeting the climb gradient to overfly the obstacles; it assumes that you'll be able to "see and avoid" these obstacles if the weather is that good or better. In the USAF we're not allowed to use the 1500/2. We always have to make the climb gradient posted or 200'/nm, whichever is higher, with one engine inoperative.
We do some pretty "dangerous" stuff in the air force, fly into known threat areas, 330 knots 300 feet off the ground, formation airdrop/air refueling, and we aren't allowed to see and avoid obstacles on departure. So if I ever do any private IFR flying again, I'm probably not going to use the "see and avoid" procedure, If I can't climb over it, I ain't goin. Just my 2 cents....
The 1500/2 is in lieu of meeting the climb gradient to overfly the obstacles; it assumes that you'll be able to "see and avoid" these obstacles if the weather is that good or better. In the USAF we're not allowed to use the 1500/2. We always have to make the climb gradient posted or 200'/nm, whichever is higher, with one engine inoperative.
We do some pretty "dangerous" stuff in the air force, fly into known threat areas, 330 knots 300 feet off the ground, formation airdrop/air refueling, and we aren't allowed to see and avoid obstacles on departure. So if I ever do any private IFR flying again, I'm probably not going to use the "see and avoid" procedure, If I can't climb over it, I ain't goin. Just my 2 cents....
It makes sense why the AF makes you do that. If you can't meet the climb profile then all your going to do with 1500-2 + ceiling & vis is see the mountain your going to crash into. Once you start doing turns (steeper ones) in mountainous terrain your going to lose climb performance and then bad things start to happen. I'm not saying your gauranteed to crash into a mountain if you don't meet the C/G, but you certainly will get a good look at whatever you're suppose to miss.
It makes sense why the AF makes you do that. If you can't meet the climb profile then all your going to do with 1500-2 + ceiling & vis is see the mountain your going to crash into. Once you start doing turns (steeper ones) in mountainous terrain your going to lose climb performance and then bad things start to happen. I'm not saying your gauranteed to crash into a mountain if you don't meet the C/G, but you certainly will get a good look at whatever you're suppose to miss.
That's all correct, but don't forget that included in the " see and avoid" is an escape manuever. I.E. "i'm going to fly down the valley" etc. etc. I definetely agree however that i would not go either!
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. It all makes sense now, thank you very much.
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