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Air Traffic Monitoring => Aviation Audio Clips => Topic started by: Fryy/Avocadoflight on September 18, 2007, 03:32:30 AM

Title: Video: Fatal Take-Off
Post by: Fryy/Avocadoflight on September 18, 2007, 03:32:30 AM
Saw this in another forum and found it interesting considering all factors involved.

http://www.liveleak.com/view?i=a06_1188732892
Title: Re: Video: Fatal Take-Off
Post by: moto400ex on September 18, 2007, 09:31:08 AM
Thats odd that they would blame warmer weather for the plane not being able to climb although it is possible.  It looks like the plane stalled shortly after lift off.  How many people were onboard? The plane may also have been overloaded.
Title: Re: Video: Fatal Take-Off
Post by: Biff on September 18, 2007, 10:55:01 AM
It's called Density Altitude (http://en.wikipedia.org/wiki/Density_altitude) and it's been a factor in plenty of crashes just like this one.  It usually does result in a stall because the aircraft can't generate enough lift to climb out, and you can't exactly fly cross country in ground effect.
Title: Re: Video: Fatal Take-Off
Post by: moto400ex on September 18, 2007, 12:04:07 PM
ohh density altitude... i always fly around in ground effect so i dont need to worry about that.
Title: Re: Video: Fatal Take-Off
Post by: moto400ex on September 18, 2007, 12:10:07 PM
That ladies description of what happened how it crumbled in the sky was a prime example of how observers that report witnessing an accident to the FAA tend to over exagerrate what happened.
Title: Re: Video: Fatal Take-Off
Post by: KSYR-pjr on September 18, 2007, 01:17:29 PM
ohh density altitude... i always fly around in ground effect so i dont need to worry about that.

LOL, although technically speaking even if you did have a craft that only flew in ground effect you would still need to be aware of the effects of DA on your craft's capability to generate lift.   Place a Cessna 150 at a runway with a density altitude of 15,000 feet and you most likely are not even leaving the ground to enjoy ground effect.
Title: Re: Video: Fatal Take-Off
Post by: pocho on September 18, 2007, 07:35:07 PM
I have had instances where I've had to cancel cross country flghts due to the extreme heat (115F-120F) and high humidity levels, in a 172.

Hotter air -> high humidity -> less dense air = less lift. And of course, a heavily loaded plane creates a dangerous situation.

Now it's a bit cooler here, thankfully. We just saw double-digit highs for the first time in months, today.
Title: Re: Video: Fatal Take-Off
Post by: moto400ex on September 18, 2007, 08:36:27 PM
Of course I understand the concept of density altitude.   Im a commericial multi instrument pilot I dont need an explanation.  Its just not too often Ive heard of that being the cause of a crash.
Title: Re: Video: Fatal Take-Off
Post by: KSYR-pjr on September 18, 2007, 09:06:51 PM
Of course I understand the concept of density altitude.   Im a commericial multi instrument pilot I dont need an explanation.

Well, until Dave figures out a way to put all of our extensive aviation resumes next to our forum moniker you are just going to have to be patient with those of us who don't know your lengthy credentials after reading all 14 of your posts.

Its just not too often Ive heard of that being the cause of a crash.

BS.  Every commercial, multi instrument pilot would definitely know that the effects of DA can lead to a crash.  In fact, every private, non-instrument, non-multi would know that.  I ask this in the least derogatory way possible:  Are you rated in real life or MSFS?
Title: Re: Video: Fatal Take-Off
Post by: Hollis on September 18, 2007, 09:54:59 PM
Not to muddy the waters any further, but assuming no mechanical or engine problem, that accident was caused by an overweight aircraft trying to fly in atmospheric conditions not adequate to provide a positive rate of climb out of ground effect. Three factors: reduced wing lift, reduced propeller thrust and substantially reduced engine output HP.
For a demo, climb to a safe altitude, with full power on, trim out at about 5 knots above stall for your weight, then pull on full carb heat and watch what happens.
Title: Re: Video: Fatal Take-Off
Post by: moto400ex on September 18, 2007, 11:39:52 PM
Well If you read what I wrote first I never said that it was not possible.   I didnt go into detail about density altitude as i am not familiar with the area where the plane departed from and the conditions that it tryed to depart in. (It says warmer air) But it also says the plane was headed for mexico hinting that it also could be overloaded with god knows what.  Most of my flying is done on the east coast and midwest so density altitude has never been a big concern as field elevations are relatively close to sea level.  And yes I do realize that I am low on the totem pole here at liveatc.net as I have just gotten into looking at forums about atc.  Yes its easy to question my certificate and ratings but I have no reason to lie about it.  Unfortunalty I couldnt pass my private pilot checkride in flight simulator so I am obviously not rated there but it does help for anyone doing instrument training.  I have recieved all my training from an accredited university.  I just recieved my commercial cert last semester.  Our university plans it out so you get your commercial instrument multi all in one checkride.
Title: Re: Video: Fatal Take-Off
Post by: KSYR-pjr on September 19, 2007, 12:31:30 PM
Well If you read what I wrote first I never said that it was not possible.   

I read what you wrote and what you stated was this:  "Its just not too often Ive heard of that being the cause of a crash."  If you truly understood the concept of DA, you should have absolutely no problem with that being listed as a factor in this or any crash. 

In an earlier post I see that you asked about the meaning of "Nordo," (http://www.liveatc.net/forums/index.php/topic,3560.msg20225.html#msg20225) which should be another easily recognizable concept to those who are rated to fly.  If you really are commercial, multi-engine, instrument-rated pilot might I humbly suggest that you do your potential passengers a favor and get some actual left seat time to accumulate more than just book experience?  They and all of GA (which has a less-than-stellar reputation among the masses thanks to many high-profile accidents) will be most appreciative.
Title: Re: Video: Fatal Take-Off
Post by: Hollis on September 19, 2007, 12:56:33 PM
The NTSB report:

My comments -
Density altitude computes to at least 3800 ft.
Maximum TOGW at SL = 3650 lbs. His TOGW computes to 3638 lbs.
Max SL HP is 300. His max available TO HP computes to 285.
Due to the lower HP and air Density ratio combination, his max propeller thrust available was less than 90% of SL rated thrust.
In effect, his maximum rate of climb out of ground effect was NEGATIVE!
Title: Re: Video: Fatal Take-Off
Post by: moto400ex on September 19, 2007, 01:46:09 PM
Well  I have 230 hours total time about and I fully understand the concept of density altitude and the effect it has on aircraft of any kind.  Im sorry I havent read too any ntsb reports about aircraft crashing due to density altitude.  I will try to research to try and further my knowledge about this.  I still never said anywhere that it wasnt possible not sure where you are finding that...  About Nordo I have never heard it in my flying and it not in any training course outlines that I know of for me.  I asked my Multi intstructor and had never heard of it so I proceeded to ask some people in the air traffic control department where I got an answer from a controller who has worked in denver center.  Ill ask my CFI teacher today shes and ATP and see if she knows... Ill let you know :-)
Title: Re: Video: Fatal Take-Off
Post by: KSYR-pjr on September 19, 2007, 02:12:33 PM
My comments -
Density altitude computes to at least 3800 ft.
Maximum TOGW at SL = 3650 lbs. His TOGW computes to 3638 lbs.
Max SL HP is 300. His max available TO HP computes to 285.
Due to the lower HP and air Density ratio combination, his max propeller thrust available was less than 90% of SL rated thrust.
In effect, his maximum rate of climb out of ground effect was NEGATIVE!

Hmmm, not exactly sure how you arrived at a negative climb out rate.   Not necessarily doubting you as this reads to me like some kind of theory from aeronautical engineering but could you expand a bit and show your work.  :)

In a more practical sense, GA aircraft are delivered with takeoff and landing distance charts in the POH that a pilot is supposed to use to calculate take off distance needed.    The charts are normally designed so that no complicated math is needed.  Taking into account wind direction and speed, density altitude, take off weight,  slope of runway, and any obstacles at the end of the runway, a pilot can derive safe takeoff distance using these charts.

It is suggested that pilots add anywhere from 20 to 50% to the takeoff distance pulled from these charts to account for the fact that these charts are produced under the best possible conditions (new engine, test pilot skills, properly inflated tires, etc.).  Therefore, if the takeoff conditions resulted in a chart-derived TO distance of (for example purposes only) 2,700 feet, one would add a fudge factor of 540 feet up to 1,350 feet, or a total distance of 3,240 to 4,050 feet of runway distance needed.

A tip I read from a well-known mountain flying guru is that if you reach about 70% of takeoff speed within 50% of the runway, continue the takeoff.  Otherwise, abort.  Of course, this requires a pilot plan the takeoff enough to know where the halfway point of the runway is and have the confidence enough to abort with a plane full of passengers wanting to get to their golf outing.






Title: Re: Video: Fatal Take-Off
Post by: moto400ex on September 19, 2007, 07:10:00 PM
Well to KSYR-pjr Ive asked my CFI teacher she says has heard the term before when she was flying as she was a Northwest airlines F/O.  Its not a term they teach in any of my aviation courses that I know of here although it seems to be widley accepted term in ATC. 
Title: Re: Video: Fatal Take-Off
Post by: mk on September 19, 2007, 07:24:24 PM
There was a Bonanza crash last week most likely due to overgrossed conditions and density altitude. 

Elizabethton, TN.  http://www.ntsb.gov/ntsb/brief.asp?ev_id=20070907X01326&key=1

Title: Re: Video: Fatal Take-Off
Post by: Hollis on September 19, 2007, 07:48:21 PM
An identical Model aircraft under nearly the same flight conditions, and the exact same results.
I'd say that pretty much tells the story!
Title: Re: Video: Fatal Take-Off
Post by: KSYR-pjr on September 19, 2007, 09:02:38 PM
There was a Bonanza crash last week most likely due to overgrossed conditions and density altitude. 

I came across that one the other day while perusing the accident database.  Man, that sucks.  Five people dead.  This is the type of accident that just destroys GA in the eyes of the non-flying masses.
Title: Re: Video: Fatal Take-Off
Post by: KSYR-pjr on September 19, 2007, 09:04:39 PM
Well to KSYR-pjr Ive asked my CFI teacher she says has heard the term before when she was flying as she was a Northwest airlines F/O.  Its not a term they teach in any of my aviation courses that I know of here although it seems to be widley accepted term in ATC. 

Very good.  Like I alluded to before, nothing beats book smarts like actual experience.  Get out there and fly somewhere.
Title: Re: Video: Fatal Take-Off
Post by: moto400ex on September 19, 2007, 09:39:42 PM
Ill agree with you there... its hard to get out and fly somewhere else while I am at school as most of my flying takes place locally and there are very few cross country flights I can actually do right now.   Ive only been flying for 2 years so yes im relatively new.  I guess the most experience I will get is out in the real world when I get a job.  I guess you could say its a downside to going to an aeronautical university.  You are very limited on where you can go and what you can do. 
Title: Re: Video: Fatal Take-Off
Post by: RayZor on September 19, 2007, 09:50:38 PM
let me share with you a little story...

a few weeks ago i took my cfi, my friend, and a full load of fuel up in a 1973 warrior.  the temperature was 105 degrees.  we had 6500 feet of runway to work with, so my cfi thought it would be a good lesson....it took almost the full length of the runway to build up enough speed to establish a safe climb...6500 feet!! 

Don't be fooled...Density Altitude kills pilots.
Title: Re: Video: Fatal Take-Off
Post by: Hollis on September 19, 2007, 10:05:09 PM
A good lesson for sure! You were lucky though - you're CFI was pushing the envelope just a wee bit there.
For anyone wanting to experience the effects of density altitude, try this when you have some spare time:
Do a normal full throttle take-off and note the time and distance to your lift-off speed. Now try the same thing but using only constant 80% power from brake release (but be prepared to firewall the throtttle just in case).
Been there, done that...

Title: Re: Video: Fatal Take-Off
Post by: Claude Christie on September 20, 2007, 02:05:16 PM
I did know the meaning of NORDO but decided to see how quick I could locate the info. by using google.  In a few seconds the explanation was on my screen.  Give it a try.
Title: Re: Video: Fatal Take-Off
Post by: moto400ex on September 20, 2007, 04:28:09 PM
Oh really... whats google never heard of it before.... is it another atc site?     :-P
Title: Re: Video: Fatal Take-Off
Post by: Claude Christie on September 22, 2007, 03:21:51 AM
www.google.com
Title: Re: Video: Fatal Take-Off
Post by: Claude Christie on September 22, 2007, 03:23:09 AM
RONLY is another term to look up.
Title: Re: Video: Fatal Take-Off
Post by: Claude Christie on September 22, 2007, 03:49:46 AM
Oops RONLY did not work using google.com it means receive only when an aircraft cannot transmit but can still receive.
Title: Re: Video: Fatal Take-Off
Post by: Hollis on September 22, 2007, 09:06:56 AM
Just Google 'radio term RONLY'.
The first link tells it all.
Title: Re: Video: Fatal Take-Off
Post by: Lezam on September 23, 2007, 02:02:09 AM
Really sad video... they could have never expected that coming, happened so fast
Title: Re: Video: Fatal Take-Off
Post by: moto400ex on September 23, 2007, 01:00:52 PM
Yea so much for following 91.103
Title: Re: Video: Fatal Take-Off
Post by: keith on September 25, 2007, 09:24:09 AM
The NTSB report:

My comments -
Density altitude computes to at least 3800 ft.
Maximum TOGW at SL = 3650 lbs. His TOGW computes to 3638 lbs.
Max SL HP is 300. His max available TO HP computes to 285.
Due to the lower HP and air Density ratio combination, his max propeller thrust available was less than 90% of SL rated thrust.
In effect, his maximum rate of climb out of ground effect was NEGATIVE!



I too am confused by the conclusion you draw at the end of this.  What you're saying, then, is that given standard pressure and temperature, the plane would not have been able to climb beyond 3800' MSL, and I can't quite get my head around that.
Title: Re: Video: Fatal Take-Off
Post by: KSYR-pjr on September 27, 2007, 11:21:41 PM
I too am confused by the conclusion you draw at the end of this.  What you're saying, then, is that given standard pressure and temperature, the plane would not have been able to climb beyond 3800' MSL, and I can't quite get my head around that.

Apparently the opportunity for both you and me to learn something new every day is not going to happen anytime soon?  I have been holding my breath for an explanation but have turned three shade of blue with no relief in sight.
Title: Re: Video: Fatal Take-Off
Post by: Hollis on September 28, 2007, 03:26:33 AM
Well OK, here goes:
Rate-of-climb is directly proportional to the Absolute temperature ratio.
Engine BHP (Brake HP) is proportional to the square root of the air density ratio.
Propeller efficiency is likewise proportional to the air density ratio.
Wing stall INDICATED airspeed is directly proportional to gross weight.
TRUE airspeed (i.e., ground speed) is a function of temperature. (Hence a longer take-off roll at higher temps).
Rate-of-climb is approximately 20% higher in ground effect than in free air.
Rate of climb decreases proportionally to the decrease in airspeed below the BROC speed (Typically about 20% above stall speed).

(Now, for my own 'amusement', I used Microsoft Flight Simulator and took the Cessna to Livermore, CA airport and tried a few take-off runs simulating the conditions of the accident. With a 10% reduction in TO power to duplicate the high temp effect of HP loss, I got airborne, but crashed in 4 out of 5 attempts. With an HP reduction of 8%, I managed to stay airborne, but could neither gain altitude or airspeed. Any attempt to turn resulted in a sink rate toward the ground).

For further enlightenment, read up on mountain flying!



Title: Re: Video: Fatal Take-Off
Post by: KSYR-pjr on October 02, 2007, 08:52:48 AM
Rate of climb decreases proportionally to the decrease in airspeed below the BROC speed (Typically about 20% above stall speed).

So, what's the calculation that determines rate of climb?   I still don't understand how you are concluding that the aircraft in the video experienced a negative rate of climb using the ratio above, which you are saying is proportional (a decrease in one is tied directly to the decrease in the other).  Can't have a negative airspeed so you can't have a negative rate of climb unless there is something else not obvious.

You don't have to bother with explaining the above if it becomes too much work.  I will research it when I am ready to take a mountain flying course.

One question I have that you perhaps could answer:   What is the Absolute Temperature ratio?   Absolute temperature to me is temperature measured relative to absolute zero, typically expressed on the Kelvin scale.   







Title: Re: Video: Fatal Take-Off
Post by: Hollis on October 02, 2007, 09:47:16 AM
You are correct regarding absolute temperature being on the Kelvin scale. In this incident the ratio would be :
Standard S.L.  OAT + 273 (= 15+273), divided by observered OAT + 273 (=
42+273), or 0.91. In other words, his max HP available was only 91% of S.L. rated HP due to temperatiure alone.
A negative rate-of-climb is simply a rate of descent. It results from the thrust being less than the drag. The equation is:
(T - D)/W. You can't climb unless T is greater than D for a given weight.
And increased weight equals increased drag since a higher angle of attack is needed to generate the lift required to balance or overcome the weight.
And yes, it is a complex mathematical process.
Title: Re: Video: Fatal Take-Off
Post by: realscooter on October 11, 2007, 07:05:25 PM

And yes, it is a complex mathematical process.

Which, I must say, you have explained so well, that even myself, who is useless in math, can understand.

I'm new to this forum, kinda stumbled in and got interested.
I'm no pilot except for MSFS, which I started using to overcome my fear of flying. It helps a lot, because I now better understand what happens and why tons of steel do fly.

I remember having been on an Aer Lingus flight from EDDL (Dusseldorf, Germany) to EIDW (Dublin, Ireland) on a very hot and humid summer day (temperatur was 36 Celsius, don't know how much that is in Fahrenheit but I expect it to be in the hundreds).

We used a good deal more of the runway than I usually witness there in the same type of aircraft, the initial climb out of the airport was unstable and rough - just what I don't like - until about 4.000 ft.  (taken into consideration my knowledge of the terrain, because I live in the aerea and the SID routes of the airport).
The guy next to me told me it was because of the heat. I assume this must have been "High Density"?!

Thanks for all the interesting information and the entertaining chatter between pilots, soon-to-be-pilots and other non-pilots like myself.

Martin
Title: Re: Video: Fatal Take-Off
Post by: Hollis on October 11, 2007, 07:25:08 PM
Your 36C equates to 97F, which is still pretty warm/hot.
The relationship is: 9/5C+32 = F.
The higher temperature causes both a higher 'density altitude' and a 'true airspeed', which is why it requires a longer take-off run to reach the proper take-off 'indicated' airspeed. (As seen on the instrument).
Title: Re: Video: Fatal Take-Off
Post by: dmccabe79 on October 30, 2007, 11:12:38 PM
You 250 hour pilots are killing me.  NORDO is primarily an ATC used thing. 
Although when you squawk 7600 it shows "RDOF" on the datablock...go figure.
Title: Re: Video: Fatal Take-Off
Post by: moto400ex on October 30, 2007, 11:48:35 PM
You 250 hour pilots are killing me.  NORDO is primarily an ATC used thing. 
Although when you squawk 7600 it shows "RDOF" on the datablock...go figure.

I think we have established that a long time ago.
Title: Re: Video: Fatal Take-Off
Post by: KSYR-pjr on October 31, 2007, 09:09:54 AM
You 250 hour pilots are killing me.  NORDO is primarily an ATC used thing. 

Ah, sheesh, this again?   
Title: Re: Video: Fatal Take-Off
Post by: RayZor on October 31, 2007, 06:38:38 PM
NORDO!? What does THAT mean?!?!  :wink:
Title: Re: Video: Fatal Take-Off
Post by: cessna157 on November 02, 2007, 12:04:11 AM
NORDO!? What does THAT mean?!?!  :wink:

Nordo is simply someone's nickname.  Probably a friend of the controller.  Short for Norman?
Title: Re: Video: Fatal Take-Off
Post by: JBnut on November 26, 2007, 07:21:39 PM
NORDO means that a pilot has no radio communications or radio has failed





JB

Air Traffic Controller
Title: Re: Video: Fatal Take-Off
Post by: KTUS on November 27, 2007, 09:02:16 PM
This safety document explains density altitude pretty well and also includes a standard Koch chart on page 3. The Koch chart is not meant to be an absolute for every aircraft or to replace proper aircraft testing, but does give an indication for what kind of performance degradation might be expected. YMMV, etc...

http://www.gofir.com/aviation_accident_prevention_program/docs/pdf/density_altitude.pdf
Title: Re: Video: Fatal Take-Off
Post by: aviator_06 on December 09, 2007, 06:46:35 PM
Density Altitude will do that.
Title: Re: Video: Fatal Take-Off
Post by: Discombobulato on December 15, 2007, 02:39:46 AM
It was a very weird week. I live in the town next to Cameron Park, which is where the video was taken, and I heard of the accidents. Less than 20 miles away (I believe it was the day before or after) another plane crashed as well, but that pilot came out alive. From what I heard, there were 4 people on the plane, and that probably contributed to the lack of lift.
Title: Re: Video: Fatal Take-Off
Post by: asrlb45 on January 30, 2008, 11:36:44 PM
Did anyone notice that the trees in the foreground appeared to indicate a tailwind?? Overgross? Engine not producing full rated power?
Title: Re: Video: Fatal Take-Off
Post by: Robin Rebhan on January 31, 2008, 07:01:12 PM
Official NTSB Preliminary report at;
  http://www.ntsb.gov/ntsb/brief.asp?ev_id=20070910X01354&key=1