Uphill or downwind departure which would you choose?

J

Jthamilton

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Okie182
Flew the family to KCUT to see Mount Rushmore this weekend as a little get away. Nice place, field around 5600'. I departed on Saturday morning, Density altitude was at 7,000'. I landed on runway 8 on arrival. Departing on 8 there was 5 knot tailwind or I could depart 26 which has 1.3 degree uphill grade.

I pondered a little, wasn't close to gross. Have the Turbo, and everything has been running well.

I chose 26 and everything went well. Personally I think they kinda cancel each other out!

While chatting with another pilot prior to departure he brought this issue up and I'm curious how anyone else would think about it.
 
Did you consult your POH performance section for wind and grade correction factors? If so, how did the numbers turn out?

Jthamilton said:
Flew the family to KCUT to see Mount Rushmore this weekend as a little get away. Nice place, field around 5600'. I departed on Saturday morning, Density altitude was at 7,000'. I landed on runway 8 on arrival. Departing on 8 there was 5 knot tailwind or I could depart 26 which has 1.3 degree uphill grade.

I pondered a little, wasn't close to gross. Have the Turbo, and everything has been running well.

I chose 26 and everything went well. Personally I think they kinda cancel each other out!

While chatting with another pilot prior to departure he brought this issue up and I'm curious how anyone else would think about it.
Click to expand...
 
Good choice , I would prefer uphill as opposed to a tail wind on take off.tailwinds can be a problem on both take offs and landings.
 
I flew into 14A Lake Norman near Charlotte in NC. Its runway varies from 1-1.4%. The local I spoke with there said they all take off downhill and land uphill until the winds are greater than a 20 knot tailwind.

I suspect the effect of wind would be greater significance with planes that have lower V speeds.
 
I regularly fly into a 2000' private strip with 80' of rise to the north...roughly 4%. I also fly into a few other strips with varying slope, though the 4% strip is by far the steepest.

Between what my book tells me (which in 1958 wasn't much) and experience I've come to the conclusion, as illogical as it might be, that 1% = 6 to 7 kts.

i.e.

10 kts blowing down a 1% slope, take off uphill.

10 kts blowing down a 2% slope, take off downhill.

But that's MY airplane.
 
IME: Baron: 1% = 10 knots, in an E55, which is how the Baron pilot at St. Ignace met his end.
 
There's a rule of thumb, I wont repeat it here, it's probably good enough to just barely kill you.
 
bbchien said:
IME: Baron: 1% = 10 knots, in an E55, which is how the Baron pilot at St. Ignace met his end.
Click to expand...
Any one must understand that this simply means a 1% upslope decreases takeoff performance as much as a 10 Kt tailwind (i.e. causes a fairly significant increase in required runway length).
 
bartmc said:
There's a rule of thumb, I wont repeat it here, it's probably good enough to just barely kill you.
Click to expand...

Thanks, very helpful.

Sparky's book on mountain flying (take it for what it's worth) says, "Generally a 1% downslope is equivalent to 10% more runway (depending on the type and condition of the surface)."
 
Winds are what they are and often vary greatly. The slope is always there. Choose wisely...
 
Samwise said:
Thanks, very helpful.

Sparky's book on mountain flying (take it for what it's worth) says, "Generally a 1% downslope is equivalent to 10% more runway (depending on the type and condition of the surface)."
Click to expand...

That's the rule I've often heard repeated.

I was based at an airport with a 3% grade, in the Rockies in western MT for 5 years, I never took off from rwy 12. There wasn't a taxiway to 12 dissuade people from going that direction. If the winds were heavily favoring 12, that was when I got the bug remover out and wiped the bugs off the wings.
 
Sorry for delay in response, on call and have little signal where I stay on call.

This wind was calm when I initially checked it, but I while packing aircraft and loading kids and waiting for inbound aircraft to land I noticed wind sock had changed so I checked AWOS. Thats when it was at the moment 5 knots. Not really gusty but the wind sock was showing some variation in wind speed and was no longer limp. I recognize I should have checked POH for performance. Instead I used the figures from Mountain flying bible of 110 increase in distance for given altitude for 1 degree slope. Some other things I did consider was departing 26 the terrain decreases and allowed straight out departure, departing runway 8 (downhill) the terrain actually rises after you cross road that takes you to the airport.

My exit strategy was if I hadn't reached 50 knots by the taxiway onto runway I would abort and consider a switch. Since taking my Mtn flying course I like to use the 71% of takeoff speed in 50 % of the runway for adequate takeoff. I have found that the aircraft easily reaches this everytime.

Coming from Oklahoma where if there is a gradient its usually .0000001 degree, tailwinds are taught to be a terrible thing. This is exactly why I posted it and I appreciate everyones input. In hindsight if less then 10 knots next time I will departing the downhill route on runway with 1 degree gradient or less.

I will also do better preflight planning with runway gradient and expected length of takeoff in case that need arises. I have read the POH a couple times recently and reviewed the charts for altitude and although I can't quote the exact figures I was very confident in the performance in the situation. However I should confirm these next time as it only takes a minute. I always try and figure what if the turbo fails and what would I do.
 
FSI sold all their piston sims to Simcom a while back, but when the Wichita facility was operational they had a framed commendation letter from one of my friends hanging on their "wall of fame."

He described in great detail what transpired after he lost the turbo on his T-210 after departing KADS for Destin with a fully-but-properly loaded (legal) airplane.

The bottom line was that he found himself staring into windows of buildings in floors of the Galleria that he never expected to see from the cockpit of an airplane. They made it around the pattern and landed, to which he still credits his sim training.

Jthamilton said:
Sorry for delay in response, on call and have little signal where I stay on call.

This wind was calm when I initially checked it, but I while packing aircraft and loading kids and waiting for inbound aircraft to land I noticed wind sock had changed so I checked AWOS. Thats when it was at the moment 5 knots. Not really gusty but the wind sock was showing some variation in wind speed and was no longer limp. I recognize I should have checked POH for performance. Instead I used the figures from Mountain flying bible of 110 increase in distance for given altitude for 1 degree slope. Some other things I did consider was departing 26 the terrain decreases and allowed straight out departure, departing runway 8 (downhill) the terrain actually rises after you cross road that takes you to the airport.

My exit strategy was if I hadn't reached 50 knots by the taxiway onto runway I would abort and consider a switch. Since taking my Mtn flying course I like to use the 71% of takeoff speed in 50 % of the runway for adequate takeoff. I have found that the aircraft easily reaches this everytime.

Coming from Oklahoma where if there is a gradient its usually .0000001 degree, tailwinds are taught to be a terrible thing. This is exactly why I posted it and I appreciate everyones input. In hindsight if less then 10 knots next time I will departing the downhill route on runway with 1 degree gradient or less.

I will also do better preflight planning with runway gradient and expected length of takeoff in case that need arises. I have read the POH a couple times recently and reviewed the charts for altitude and although I can't quote the exact figures I was very confident in the performance in the situation. However I should confirm these next time as it only takes a minute. I always try and figure what if the turbo fails and what would I do.
Click to expand...
 
Wayne
I definitely have that concern of a failure and have been told that power is less then a NA when this occurs.

Part of my thinking was climbing terrain with mostly trees offers less opportunity then decreasing terrain with opportunity for somewhat level open areas god forbid I need to ever exercise this.

I always watch my MP go to 32 as I release breaks any hesitation then were staying put! This turbo can definitely can spoil you. I want to find someone up my way with NA 182 I can fly to get another feel for its performance. The mechanic I intend on using has one and I hope to fly with him in the very near future.

I know we must consider takeoff distance, density altitude with tailwinds and slope. However the departing terrain definitely played into my choice.
 
Just run your MP up to ~22" and leave it there for takeoff. Then you'll know. You can use the power tables to get an almost exact match to NA settings if you want better head-to-head comparison.

Jthamilton said:
Wayne
I definitely have that concern of a failure and have been told that power is less then a NA when this occurs.

Part of my thinking was climbing terrain with mostly trees offers less opportunity then decreasing terrain with opportunity for somewhat level open areas god forbid I need to ever exercise this.

I always watch my MP go to 32 as I release breaks any hesitation then were staying put! This turbo can definitely can spoil you. I want to find someone up my way with NA 182 I can fly to get another feel for its performance. The mechanic I intend on using has one and I hope to fly with him in the very near future.

I know we must consider takeoff distance, density altitude with tailwinds and slope. However the departing terrain definitely played into my choice.
Click to expand...
 
Jthamilton said:
Sorry for delay in response, on call and have little signal where I stay on call.

This wind was calm when I initially checked it, but I while packing aircraft and loading kids and waiting for inbound aircraft to land I noticed wind sock had changed so I checked AWOS. Thats when it was at the moment 5 knots. Not really gusty but the wind sock was showing some variation in wind speed and was no longer limp. I recognize I should have checked POH for performance. Instead I used the figures from Mountain flying bible of 110 increase in distance for given altitude for 1 degree slope. Some other things I did consider was departing 26 the terrain decreases and allowed straight out departure, departing runway 8 (downhill) the terrain actually rises after you cross road that takes you to the airport.

My exit strategy was if I hadn't reached 50 knots by the taxiway onto runway I would abort and consider a switch. Since taking my Mtn flying course I like to use the 71% of takeoff speed in 50 % of the runway for adequate takeoff. I have found that the aircraft easily reaches this everytime.

Coming from Oklahoma where if there is a gradient its usually .0000001 degree, tailwinds are taught to be a terrible thing. This is exactly why I posted it and I appreciate everyones input. In hindsight if less then 10 knots next time I will departing the downhill route on runway with 1 degree gradient or less.

I will also do better preflight planning with runway gradient and expected length of takeoff in case that need arises. I have read the POH a couple times recently and reviewed the charts for altitude and although I can't quote the exact figures I was very confident in the performance in the situation. However I should confirm these next time as it only takes a minute. I always try and figure what if the turbo fails and what would I do.
Click to expand...

That seems a little high.
 
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