Accelerated stalling in steep turns.

[motzartmerv]

The video speaks for itself.

 

The wreckage was found 3 years after the aircraft went missing. Unfortunately both occupants were killed.

 

It really highlights much of what we have been discussing on other threads. Note the engine was operating, it is clear case of stalling in the turn ie, stall horn sounding 3 times in the attempted 180 deg turn at low level (but high altitude)

 

Warning, its not a nice video.

 

https://www.youtube.com/watch?v=ZfPr_gZzHRw&feature=player_embedded

 

NTSB Identification: DEN84FA308 .

 

The docket is stored on NTSB microfiche number 25894.

 

Accident occurred Friday, August 10, 1984 in TABERNASH, CO

 

Probable Cause Approval Date: 12/14/1992

 

Aircraft: CESSNA L-19E, registration: N4584A

 

Injuries: 2 Fatal.

 

THE AIRPLANE DEPARTED GRANDBY 8/10/84 AND FAILED TO ARRIVE AT ITS DESTINATION. ON 8/23/87, IT WAS FOUND ON THE SLOPE OF A HIGH TREE-COVERED RIDGE. VIDEO TAPE RECOVERED FROM THE WRECKAGE PROVIDED A VISUAL AND AUDIO RECORD OF THE FLIGHT FROM TAKEOFF TO IMPACT. COMPARING THE RECORDING TO A TOPOGRAPHICAL MAP, THE FLIGHT WAS CLIMBING AND ITS ALTITUDE ABOVE THE GROUND WAS DECREASING WHEN IT CRASHED AT THE 10,200-FT LEVEL. DURING THE LAST FEW SECONDS OF THE TAPE, THE TERRAIN DOMINATED THE VIEW THROUGH THE COCKPIT WINDOW. THE PILOT MADE A 60-DEG BANK, AND THE STALL WARNING HORN COULD BE HEARD 3 TIMES DURING APRX 180 DEG OF TURN. THE AIRPLANE SUBSEQUENTLY STALLED, FLIPPED OVER, AND ENTERED THE TREES. THE DENSITY ALTITUDE WAS ABOUT 13,000 FT.

 

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:

 

IN-FLIGHT PLANNING/DECISION..IMPROPER..PILOT IN COMMAND

 

AIRSPEED..NOT MAINTAINED..PILOT IN COMMAND

 

 

[poteroo]

Appears they turned towards the rising ground? Confirms that you shoiuld always approach a ridgeline at an angle so that any 'away' turn isn't going to require much power, and the nose can/should be lowered in the turn. Anyway, at a DA of 13,000 ft, most aircraft have no climb left in them straight, let alone steep turning. I think that there has been a much better training approach to mountain flying since the 80's and less of these fully VFR accidents happen.

 

happy days,

 

 

[dazza 38]

:thumb_up: Great Video.Shows how quickly things can end in tears.

 

 

[motzartmerv]

Yea. You can easily see the instinct of the pilot, trying to hold the nose up and the trees away. The bobbing nose of the stall then the attitude coming straight back up to where it was.

 

 

[motzartmerv]

CFI, stalling at a higher IAS due to the bank angle. I know its not the same as the conventional accelerated stall, but it is still stalling at a higher speed.

 

cheers

 

 

[Guest basscheffers]

Thanks for posting. Disturbing but worth the watch. That'll be that last time you close the throttle low over a friend's house and fly slow around it to give them a good look.

 

 

[Guest basscheffers]

I did a proper accelerated stall in an RV7 a couple of months ago, mostly for the pilot to demonstrate what a fine design Van makes. On it's side at 4G, cruise power, maintaining altitude. Watch the speed bleed off and *way* before normal stall speed the nose drops. This being an RV, it was pretty much immediately flying again and without much input rolled level. (not like the Red Bull guys doing it at 10G and going upside down!)

 

Extreme example, but definitely fun and good to experience. At 3500ft!

 

 

[farri]

Here`s something that every Drifter pilot may or may not know and I hope I don`t upset anyone by posting this.

 

All the Drifters I`ve come accross have a clockwise rotating prop,from the back looking foward,being pushers and the prop so close to the verticle fin,the slipstream strikes the verticle fin on the right side.

 

In a power on stall in a level turn to the left,the high or right wing will stall first and if held stalled in the turn,the right wing will drop, if done correctly,all that`s needed,is to ease the stick foward as the right wing is droping and the AC is back to level flight.

 

Here`s the trap....... In a power on stall in a level turn to the right,the high or left wing stalls first,as well, but if held in the stall the high wing won`t drop as in the left turn and the AC will roll to the right and into the turn.

 

So why have I posted this.

 

As we are again discussing accidents caused by stalls in the turn,someone who doesn`t know this decides to do a tight turn to the right,not tight enough,tightens it up a bit more and it stalls, pilot panicks,doesn`t react fast enough, AC rolls into the turn, too close to the ground.............

 

I shouldn`t have to say this......I`m not sugesting that anyone go out and try it to see what happens,if you weren`t taught stalls in the turn and want to experience what happens,go get a good instructor.

 

Frank.

 

 

[farri]

By the term " Level turn" I meant a turn where the AC is neither climbing nor descending,a turn that`s ballanced and level with the horizon.

 

Frank.

 

 

[facthunter]

Big loads and altitude.

 

at altitude you run out of lift. lift depends on air DENSITY ( it's in the lift formula) and it's your density altitude that matters. (.Height and temperature).

 

If you keep climbing, eventually you reach a level where you are going to stall if you slow up and you will descend if you speed up. IF you do this carefully you will have reached the absolute ceiling for THAT aircraft that day.

 

If you want to effectively ADD weight to your plane, put it into a turn. It behaves exactly as if you added people (or bricks) to it. At 2G your 600 kg plane weighs 1200 kgs and 2G is easy to achieve, so what absolute ceiling would apply if you were in that situation.

 

A good 172 will get to 15,000', ( I've done it several times and "approved" for medical reasons so I am talking from experience), but you can only perform almost imperceptable turns above 12,000' WITHOUT LOSING HEIGHT.

 

The problem this unfortunate person confronted was to attempt a turn at high altitude when he was approaching rising terrain and had no room or performance to turn. Nev

 

 

[Exadios]

The video speaks for itself.The wreckage was found 3 years after the aircraft went missing. Unfortunately both occupants were killed.

It really highlights much of what we have been discussing on other threads. Note the engine was operating, it is clear case of stalling in the turn ie, stall horn sounding 3 times in the attempted 180 deg turn at low level (but high altitude)

 

Warning, its not a nice video.

 

https://www.youtube.com/watch?v=ZfPr_gZzHRw&feature=player_embedded"

 

NTSB Identification: DEN84FA308 .

 

The docket is stored on NTSB microfiche number 25894.

 

Accident occurred Friday, August 10, 1984 in TABERNASH, CO

 

Probable Cause Approval Date: 12/14/1992

 

Aircraft: CESSNA L-19E, registration: N4584A

 

Injuries: 2 Fatal.

 

THE AIRPLANE DEPARTED GRANDBY 8/10/84 AND FAILED TO ARRIVE AT ITS DESTINATION. ON 8/23/87, IT WAS FOUND ON THE SLOPE OF A HIGH TREE-COVERED RIDGE. VIDEO TAPE RECOVERED FROM THE WRECKAGE PROVIDED A VISUAL AND AUDIO RECORD OF THE FLIGHT FROM TAKEOFF TO IMPACT. COMPARING THE RECORDING TO A TOPOGRAPHICAL MAP, THE FLIGHT WAS CLIMBING AND ITS ALTITUDE ABOVE THE GROUND WAS DECREASING WHEN IT CRASHED AT THE 10,200-FT LEVEL. DURING THE LAST FEW SECONDS OF THE TAPE, THE TERRAIN DOMINATED THE VIEW THROUGH THE COCKPIT WINDOW. THE PILOT MADE A 60-DEG BANK, AND THE STALL WARNING HORN COULD BE HEARD 3 TIMES DURING APRX 180 DEG OF TURN. THE AIRPLANE SUBSEQUENTLY STALLED, FLIPPED OVER, AND ENTERED THE TREES. THE DENSITY ALTITUDE WAS ABOUT 13,000 FT.

 

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:

 

IN-FLIGHT PLANNING/DECISION..IMPROPER..PILOT IN COMMAND

 

AIRSPEED..NOT MAINTAINED..PILOT IN COMMAND

The maximum roll I can see is about 45 degrees (around frame 973) - assuming that the camera is fixed to the airframe. It is hard to know what is off screen but I would guess that had the pilot put the nose down to maintain airspeed then he would have made it. His mistake was to stall.

 

In Australia the pilot must be on oxygen at 10000' and greater. Some pilots go on oxygen at about 9000' if they are up there for some time (an hour or more). In addition density altitude affects lungs in the same way as it affect carburetors. So there is a definite possibility that the pilot's judgment was affected.

 

Looking at around frame 1048 I think I can see a lenticular. If this is so the aircraft may have been in rotor. These are one of the risks of flying at, or below a ridge line - on the wrong side. We nearly lost a Pawnee in one. The pilot recovered by putting the nose down to get some real speed and came out at about 500' AGL.