Avoiding crashes

[Ed Cesnalis]

Yesterday was too turbulent for a scenic flight with my girlfriend's sister. Our flight lasted 25 minutes and soon after a skyhawk did a stall / spin into the ground on departure.

 

I'm amazed that there were no fatalities though all 4 aboard required surgery and at least 1 has major injuries.

 

recipie for disaster:

 

1)high density altitude, IIRC da was over 7,000'

 

2)low power to weight ratio. the 172 had full fuel, 4 passengers, and was likely only 165hp.

 

3)uphill takeoff into turbulent conditions and rising terrain. there was a lot of headwind but a lot of sink and sheer

 

4)not familiar. the pilot is from Ridgecrest, CA a place with meaningful challenges due to conditions. mammoth is 4,000' higher and is close to the terrain. an uphill takeoff on 27 with sheer means a nose low attitude even in my ctsw. it might mean eating up 3-4,000' of runway without establishing a positive rate of climb.

 

5)failure to maintain airspeed, thermals and downdrafts change your pitch attitude for a given airspeed. hi da, over gross, low performance (was he leaned for best power?). all these things change your climb-out pitch attitude.

 

I have seen a number of crashes here, what they seem to have in common is out of the area pilots making bad decisions. flying in the mountains is rewarding but when you are away from home remember to maintain airspeed and avoid rising terrain. our ct's are nimble, there is no reason to fly them into terrain or spin them into the ground.

[coppercity]

They were very lucky no one was killed.

 

You hit the nail on the head, high DA, a full (maybe even over gross) aircraft, and unfamiliar area is not a good combo!

 

Those of us that fly in the mountains and at high DA's accept the fact our airplanes don't perform as well, but when you are used to flying at or near sea level those long takeoff rolls and slow climbs can catch you by suprise. The typical reaction to slow climbs is to try and pull back more expecting to increase the climb rate, unfortunatly we can see from your picture what happens when you do that.

[Ed Cesnalis]

... The typical reaction to slow climbs is to try and pull back more expecting to increase the climb rate, unfortunatly we can see from your picture what happens when you do that.

 

your exactly right eric,

 

the lesson here involves some additional factors. i arrived at the airport around 7:00AM and observed dust devils in the runway environment. i got tail winded when i turned crosswind, maintaining airspeed this day meant adjusting your pitch attitude time and again due to sheer and sink.

 

i talked to my hangar-mate and his comment was "you know how you have to lower your nose when departing 27 in turbulence"

 

slow climbs are an issue but the stuff hits the fan when you are past your point of no return (take off abort) and you can't maintain clearance from the terrain.

 

IMHO a key bit of knowledge is that sink turns to lift and lift turns to sink. if you are overcome by either it will generally change. there are 2 ways of keeping some energy (insurance) in your pocket. 1)airspeed; 2)altitude, if you give up airspeed you loose ability to maneuver. better to be fast then high on departure (better to be high then fast on approach)

 

IMHO a key skill is the ability to maneuver near terrain when at the mercy of conditions. often maintaining optimum airspeed gives you the ability to maneuver as options are diminishing. when you give up your airspeed you are at the mercy of the conditions, when you give up altitude you are dependent on your skills.

 

in dessert / mountain / thermal / gusty conditions the departure conditions can change, maintain airspeed not attitude.

 

in the case of this crash it is possible that contact with the terrain was inevitable (once the abort point was passed) but if airspeed was maintained then contact with the terrain could have been controlled.

[Dave]

Charlie Tango: Just to check, on takeoff are your flaps at 15 when conditions like these exist? Or at your home field are you always at 15 on takeoffs?

Dave

[Ed Cesnalis]

Charlie Tango: Just to check, on takeoff are your flaps at 15 when conditions like these exist? Or at your home field are you always at 15 on takeoffs?

Dave

 

 

dave,

 

yes 15 is standard with me. here there is a chance of encountering meaningful sink when trying to climb away from the runway. max angle of climb means a lot.

[207WF]

Ed:

 

Have you checked what your ias really is at Vx? I did some experimentation recently and even at flaps -6 it seems that Vx according to my FD indicator is between 50 and 55 knots.

 

WF

[Ed Cesnalis]

Ed:

 

Have you checked what your ias really is at Vx? I did some experimentation recently and even at flaps -6 it seems that Vx according to my FD indicator is between 50 and 55 knots.

 

WF

 

i never check, i use 58kts (15 degrees) for Vy . i don't climb slower then that around here much do to lots of wind sheer. i'd be thinking too much about getting tailwinded when at 50kts.