I had an oh s**t moment...

Sac Arrow

Sac Arrow

Touchdown! Greaser!
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Snorting his way across the USA
Look I do a lot of mountain flying. A lot. But I almost got bitten today.

I flew in to Angwin (edit mistakenly said Columba) airport (2O3). It's not particularly high, but it was a hot day, and there is some particularly nasty terrain surrounding it. Well landing was no big deal, it's a long strip (3,200 and some odd feet) but taking off was a bit different.

Runway is 16/34. I was parked at the 34 end, as everything is at that end. Wind was pretty much a direct crosswind. At the time I took off it was favoring 34 slightly. So I took off.

Then the wind shifted. Holy crap, I'm like... committed. My groundspeed is through the roof but airspeed isn't what it should be. I lift off, get to Vy, and...why ain't I climbing!! Well I was climbing, rate of climb was okay but angle of climb was no bueno.

Those trees were closing in fast. It don't look good. I double check everything including making sure I locked out the gear autoextend. I have full power. Resist the urge to pull up. Just maintain Vy. I cleared the trees, but not at the margin that I was comfortable with.

WHAT DID I DO RIGHT?

I remembered to lock out the gear autoextend. I remembered to keep airspeed where it needed to be. I resisted the urge to climb out at something slower than Vy as the density altitude was already fairly high.

WHAT DID I DO WRONG?

Well I could have taxied down the runway and took off 16 instead of 34. But what would the winds have been? If I was psychic that would have been the choice. That might have been a better choice in a marginal decision given the obstacles and terrain.

This strip is peculiar - there is a fairly long taxiway that leads from the ramp directly in line with the runway. I COULD have done a full power takeoff run from the ramp, on the taxiway, and just considered it the extension of the runway. My guess is the locals do that.

I mean it worked out, but, some lessons were learned.

Anyway not all of us are perfect. Just sharing.
 
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Sac Arrow said:
......I lift off, get to Vy, and...why ain't I climbing!! Well I was climbing, rate of climb was okay but angle of climb was no bueno.......
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did you try climbing out in English? :rofl:

jk, glad you are ok and sounds like you are making 'mental notes' to learn from the experience. don't beat yourself up!
 
Skylane81E said:
Could have climbed VX as well

Thanks for sharing!
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Good point, although the density altitude was high enough it wouldn't have made a whole lot of difference. I mean, still, every foot counts. Add that to the "wrong" list.
 
A miss is as good as a mile, but I'm in the "You could have pulled to Vx" camp as well, as you said, every foot counts, but it's only that first extra foot that makes a difference.
 
Should you have been using a lower Vy for the density altitude? I know Vy and vx approach each other as you get to the service ceiling but no poh's that I've seen have a correction for this. Maybe it doesn't make that much of a difference.
Also, with hindsight and the performance charts in front of you, do you think you we're getting book numbers? This is something I aspire to check more regularly.
 
Yes, I have had it close there, too on a high DA day. Now, I always do a short field out of Columbia and try to stay light.
 
Columbia is O22. 2O3 is Angwin.

Angwin has some fun due to the ridge, and no AWOS nor windsock nor similar airport nearby, so changing conditions can surprise. But the inline taxiway is fairly long, and can be used for takeoff as long as you're sure all the parked and derelict aircraft are out of the way.

I'm glad you made it. That sounds scary.

Taking off in the other direction has higher obstructions.

I'm sure you know this, but Vy is lower at high DA, and PA28s don't seem to like to climb well at sea level Vy at high DA. I tried that once at Big Bear; it climbed a LOT better at 65 KIAS than 75. But how high could the DA have been? Field elevation is around 1800; I can't imagine DA there getting above 5000 or so.
 
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MAKG1 said:
Columbia is O22. 2O3 is Angwin.

Angwin has some fun due to the ridge, and no AWOS nor windsock nor similar airport nearby, so changing conditions can surprise. But the inline taxiway is fairly long, and can be used for takeoff as long as you're sure all the parked and derelict aircraft are out of the way.

I'm glad you made it. That sounds scary.

Taking off in the other direction has higher obstructions.

I'm sure you know this, but Vy is lower at high DA, and PA28s don't seem to like to climb well at sea level Vy at high DA. I tried that once at Big Bear; it climbed a LOT better at 65 KIAS than 75. But how high could the DA have been? Field elevation is around 1800; I can't imagine DA there getting above 5000 or so.
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Thank you, I meant Angwin. Said Columbia.

Grr
 
Oh,Angwin. I landed there a few months ago. I didn't particularly care for it, sloped runway and nothing there.
 
Sac Arrow said:
This strip is peculiar - there is a fairly long taxiway that leads from the ramp directly in line with the runway. I COULD have done a full power takeoff run from the ramp, on the taxiway, and just considered it the extension of the runway. My guess is the locals do that.
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I don't know the place but "oh yeah". It's your airport. "Anyone who might have questions, ask me later."

My *alls are still tingling. Thanks.
 
I looked at the historic weather for the area in order to make a guess at the density altitude. I don't know what time this happened, but using weather info. from KAPC and KSTS and assuming the heat of the day around 2pm and 91F I get a density altitude of around 4,800'. Doesn't sound real high, but I don't know how your bird handles DA.

So have/did you calculate DA and how did your experienced performance stack up against the book?

Almost forgot, I'm glad everything worked out OK.
 
Glad you made it.dont need another statistic.what do they say fly the airplane and you did congrats.likevthe taxi way idea.
 
The takeoff charts for my Arrow do not use DA, but rather they use PA and Temperature to create a point on the chart that intersects with aircraft weight. Directly above that point the chart gives you rotation speed and climb speed. Sac, have you plotted everything out to see what the aircraft should have done compared to what it did.

I have been practicing my short field takeoffs and landings and comparing with the charts. Recently I laminated my performance charts so I can use a dry erase marker on them.

Since we fly the same or at least very similar aircraft I am curious as to how close yours is performing to the book.
 
Sac Arrow said:
.....................
This strip is peculiar - there is a fairly long taxiway that leads from the ramp directly in line with the runway. I COULD have done a full power takeoff run from the ramp, on the taxiway, and just considered it the extension of the runway. My guess is the locals do that.

.
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..

I have never flown into that airport... But... If no traffic was coming and going,, and the terrain was clear in the direction of take off..I would have used the taxi way to depart from.:yes:..... IMHO..
 
tmyers said:
The takeoff charts for my Arrow do not use DA, but rather they use PA and Temperature to create a point on the chart that intersects with aircraft weight. Directly above that point the chart gives you rotation speed and climb speed. Sac, have you plotted everything out to see what the aircraft should have done compared to what it did.
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You should find that the point selected by a specific PA and Temp corresponds to the DA for that combination and all other combinations of PA and Temp that produce the same DA.
 
With shifting winds you could have had a slight downdraft too . . . Climbing at 400agl into a 200fpm downdraft can get exciting when the terrain is rising 150fpm. . .
 
Sac Arrow said:
Good point, although the density altitude was high enough it wouldn't have made a whole lot of difference. I mean, still, every foot counts. Add that to the "wrong" list.
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As someone pointed out, Vy decreases (and Vx increases) with DA. In addition both decrease when below MGW so at the MGW / 0 MSL Vy you were likely several knots above the true Vy and that can have a very noticeable effect on climb gradient. I suspect that had you been at the true Vy or better yet Vx you would have sweated a lot less.

BTW, this is another instance where an AoA indicator is useful as it will give the same indication at the true Vy (or Vx) regardless of the DA and aircraft weight.
 
Is the gradient significant. Here at home if the wind isn't much more than 8 I take off downhill over the flats instead of uphill into the ridge when our DA is high (as in 7500)

Glad you held steady and cleared those trees! I've eeked up over trees before and it sure feels like they are reaching up to grab your wheels :yes:
 
tmyers said:
Did you use 25* flaps?
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No flaps. Getting airborne wasn't the issue, it was climb performance.

Alexb2000 said:
I looked at the historic weather for the area in order to make a guess at the density altitude. I don't know what time this happened, but using weather info. from KAPC and KSTS and assuming the heat of the day around 2pm and 91F I get a density altitude of around 4,800'. Doesn't sound real high, but I don't know how your bird handles DA.

So have/did you calculate DA and how did your experienced performance stack up against the book?

Almost forgot, I'm glad everything worked out OK.
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That's about right. Not real high no, but enough to be a factor.

tmyers said:
The takeoff charts for my Arrow do not use DA, but rather they use PA and Temperature to create a point on the chart that intersects with aircraft weight. Directly above that point the chart gives you rotation speed and climb speed. Sac, have you plotted everything out to see what the aircraft should have done compared to what it did.

I have been practicing my short field takeoffs and landings and comparing with the charts. Recently I laminated my performance charts so I can use a dry erase marker on them.

Since we fly the same or at least very similar aircraft I am curious as to how close yours is performing to the book.
Click to expand...

I haven't run the numbers yet.


comanchepilot said:
With shifting winds you could have had a slight downdraft too . . . Climbing at 400agl into a 200fpm downdraft can get exciting when the terrain is rising 150fpm. . .
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That's quite likely - the wind was from the West so it was on the downslope of a ridge line. That's probably true.

gismo said:
As someone pointed out, Vy decreases (and Vx increases) with DA. In addition both decrease when below MGW so at the MGW / 0 MSL Vy you were likely several knots above the true Vy and that can have a very noticeable effect on climb gradient. I suspect that had you been at the true Vy or better yet Vx you would have sweated a lot less.

BTW, this is another instance where an AoA indicator is useful as it will give the same indication at the true Vy (or Vx) regardless of the DA and aircraft weight.
Click to expand...

Maybe but it's not the first time I've flown out of that airport, and I've taken off at a lot of much higher fields. It actually felt like I was taking off from a 10,000 foot DA airport. I think the above mentioned downdraft factor was the cause of it.
 
N801BH said:
..

I have never flown into that airport... But... If no traffic was coming and going,, and the terrain was clear in the direction of take off..I would have used the taxi way to depart from.:yes:..... IMHO..
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It's a weird airport. I had a chat with the manager once that the runway had been shortened into a taxiway because of 150 foot ridge next to it. It's a displaced threshold with parking and hangars alongside. It's wide enough that local procedures have you spin a donut in the middle of it to see final. I'd go for it if I had any doubts. The thing is, I'm not sure I would have had any doubts. I've been off in 3600 feet at much higher altitude.

The airport has a rep for weird air currents, as it's on a ridge.

Nearby airports don't tell you much. KAPC is at sea level and in the swamp.
 
Sac Arrow said:
That's quite likely - the wind was from the West so it was on the downslope of a ridge line. That's probably true.

Maybe but it's not the first time I've flown out of that airport, and I've taken off at a lot of much higher fields. It actually felt like I was taking off from a 10,000 foot DA airport. I think the above mentioned downdraft factor was the cause of it.
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Downdrafts from wind over a ridge can easily exceed climb performance but typically not so much when you're real close to the ground (the descending air becomes a headwind if you're climbing towards the ridge). I don't how low you 'd need to be for this though, perhaps below 100 AGL?
 
At high DA, it is probably a good idea to refer to your POH before taking off. I did that at Big Bear a few years back and ended up postponing my attempt from 1500 to 1700. Even then, my calculated climb rate was only 200 fpm, but I had a long run over the lake to gain altitude from. What truly amazed me was that my calculated and actual climb rates were identical.

Another trick I learned from reading one of Ernest Gann's books is when approaching an obstacle at low airspeed and full power, if it looks like you are going to hit it, just before impact, give it full flaps. I tried this at a safe altitude, and it works, you do get enough sudden lift to make a possible difference.

-John
 
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Locking out the auto-extend was a good call. I flew out of Ruidoso this June and did NOT override the auto-extend. Couldn't get the gear up and was in ground effect for several minutes before I hit the override :hairraise:
 
gismo said:
Downdrafts from wind over a ridge can easily exceed climb performance but typically not so much when you're real close to the ground (the descending air becomes a headwind if you're climbing towards the ridge). I don't how low you 'd need to be for this though, perhaps below 100 AGL?
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Well here the field is nested near the top of a ridgeline and the valley below is about 1000 feet below airport elevation. So, that isn't going to work. On the other hand, if you DO clear the trees and you're still descending below airport elevation, you have roughly 1,000 feet of altitude to either recover or land someplace in the valley.

John Baker said:
At high DA, it is probably a good idea to refer to your POH before taking off. I did that at Big Bear a few years back and ended up postponing my attempt from 1500 to 1700. Even then, my calculated climb rate was only 200 fpm, but I had a long run over the lake to gain altitude from. What truly amazed me was that my calculated and actual climb rates were identical.

Another trick I learned from reading one of Ernest Gann's books is when approaching an obstacle at low airspeed and full power, if it looks like you are going to hit it, just before impact, give it full flaps. I tried this at a safe altitude, and it works, you do get enough sudden lift to make a possible difference.

-John
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I read the same book I'm sure, I think he was taking off from someplace and his copilot pulled the gear too soon and he did that to avoid whacking the pavement when the plane started to settle in. Probably a good trick to have in your bag, not sure it would have made a difference for me. But, you never know. A good thing to consider.

Datadriver said:
Locking out the auto-extend was a good call. I flew out of Ruidoso this June and did NOT override the auto-extend. Couldn't get the gear up and was in ground effect for several minutes before I hit the override :hairraise:
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Yeah in my Turbo Arrow I always flew with the auto extend overridden anyway so it was never a factor. In my current partnership, the Other Guy likes to have it enabled when he flies it so I normally enable it after I'm in cruise. In any case, I've never flown an Arrow where the autoextension system performs "correctly" and doesn't hold up the retraction of the gear on climbout. I guess it's some sort of adjustment issue. Dunno.
 
The auto extend also prevents premature retraction of the gear till you are above a certain air speed. It varies slightly with different aircraft but is around 70 kts. This control was installed to prevent someone from retracting the gear too early so they did not settle back onto the runway with the gear on the way up.

There is a second airspeed mast on the left cabin wall and a diaphragm under the floor that this mast feeds. I disable my auto extend for a short field so I can raise the gear when I want, then return it to normal once the flaps are retracted and I am at Vy
 
tmyers said:
The auto extend also prevents premature retraction of the gear till you are above a certain air speed. It varies slightly with different aircraft but is around 70 kts. This control was installed to prevent someone from retracting the gear too early so they did not settle back onto the runway with the gear on the way up.

There is a second airspeed mast on the left cabin wall and a diaphragm under the floor that this mast feeds. I disable my auto extend for a short field so I can raise the gear when I want, then return it to normal once the flaps are retracted and I am at Vy
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I hate premature retraculation. My current plane only has an issue with the gear on climbout. My Turbo Arrow would want to lower the gear before I was in the pattern. I guess I sort of appreciate it's there, somewhat, but at the same time it can really bite you in the ass if you aren't paying attention.
 
Any leak, no matter how small will prevent proper actuation of the system. Our school arrow had it adjusted to allow retraction at the proper speed, however there you can stall the damn thing and not get the gear to fall out. After much chasing it wears an "AUTOEXTEND INOP" placard. During the chasing I found that if I set it to extend at the right speed it would prevent retraction until well over 100mph.
 
Either way if raising the knob raises the gear and lowering it does likewise, I'm happy. I'm not convinced that the system is going to save me. It's more likely to bite me in the ass on a heavy climbout.
 
Sac Arrow said:
Either way if raising the knob raises the gear and lowering it does likewise, I'm happy. I'm not convinced that the system is going to save me. It's more likely to bite me in the ass on a heavy climbout.
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Well neither the FAA or the insurance company batted an eye when the plane landed gear up due to pilot inattention.
 
Datadriver said:
Locking out the auto-extend was a good call. I flew out of Ruidoso this June and did NOT override the auto-extend. Couldn't get the gear up and was in ground effect for several minutes before I hit the override :hairraise:
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I fly to Ruidoso often ... taking off towards the south one trip I hit a downdraft after takeoff that was enormous. I had some altitude and turned back to the field and climbed over the airport. That airport sits in a bowl and can have some unusual mechanical over the ridges. Most of my trips there now I stay in the pattern for one circuit then depart ... the underwear gets less wear and tear that way;)
 
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