Agreed, I've mentioned tying the chute not long ago, but nobody said anything...if he did do this, he has a lot of real estate on him. money, briefcase tagging along...

I just find it odd that he spotted everything else except the dummy chute...they don't mention anything about a dummy chute in any of these files...?

Could the dummy parachute have been used as a projectile to simulate a jump?

Could D.B. Cooper have lobbed or hurled the dummy parachute as a projectile, targeted at the bottom end of the staircase of Flight 305, with sufficient impact force so as to simulate a jump?

(for reference, please see my original hypothesis, graciously posted on my behalf by Bruce A. Smith, as Reply #1688 on: May 02, 2017, 05:46:43 PM.)

I realize my hypothesis about the use of the dummy parachute comes close to heresy in standard Cooper lore, and there are probably a lot of very good arguments against it. Please, I’m not trying to step on anyone’s toes. I’m just asking, because I think it is an intriguing possibility, could this be a plausible use and scenario for the dummy parachute? I’d like to put my hypothesis out there, “for your consideration.”

Here are the dimensions for the stairwell, and for a hypothetical throw of the dummy parachute, as shown in the above diagram that I made by cropping and modifying and overlaying the original © Boeing diagram, as show on this site:

The stairwell is about 3 feet wide. The exit door is 6 feet 4 inches high. There is about 2 feet of headroom above the exit door. There are 16 steps (counting the top step,) and the hinge point of the stairway begins at step number 6, descending.

Based on several photos and diagrams I have seen and compared, I have estimated the dimensions of the interior of the stairwell as shown in this diagram. I overlaid those estimated dimensions on a portion of the schematic drawing of a side view of the stairway, as shown on this site.

Based on those specs, if Cooper used the dummy parachute as a projectile to try to simulate a jump, and he targeted the 14th step, then appears to me Cooper would have had to make a shot at a target about 17 feet 6 inches away. Cooper stood about 5 ft. 10 in. tall, so if he raised his arms overhead, he could have begun that overhead shot at a height of about 6 ft. 6 in. The shot had to hit the targeted 14th step (or close to it) about 13 ft out and 12 ft down from where the shot began.

The parachute weighed about 20 pounds. If it had dropped 12 feet in a free fall, it would strike the 14th step with about 240 foot-pounds of force. If Cooper actually “hurled” it downward, then it would have struck even harder. Either way, that is a significant force to impact the bottom of the stairway, and would have caused it to bend downward.

The parachute would strike the stairway at an angle, however, so it would still need to tumble down at least a couple more steps in order to impart as much of the downward impact force as possible, before it finally tumbled off the end. At which point the staircase would rebound, as it actually did, hard enough for the staircase to slam shut, which apparently it did.

In the diagram, I have shown a floating position for the stairway about midway between the extended position and the retracted position. I realize this would be variable at the time of the actual flight.

I’m not fully certain about the actual height of the ceiling panels in the stairwell, though I think it is fairly close to what I have shown in the diagram. But even if the ceiling panels were 2 feet lower, this hypothetical throw could still work. There is a large margin for allowable error as shown in this diagram for being able to make a successful hypothetical throw of the dummy parachute.

But would it be enough force, and would it be convincing for simulating a jump? Keeping in mind my stated assumption that Cooper was a commando, that is my question for the Forum, for your consideration.

“Could D.B. Cooper have lobbed or hurled the dummy parachute as a projectile, targeted at the bottom end of the staircase of Flight 305, with sufficient impact force so as to simulate a jump?”

Thanks and best wishes to all,  John S.

It's possible, I suppose, to spoof an exit bump, but a typical chest reserve doesn't weigh 20 lbs. I'd say it's about half that.

Did Cooper even know an exit would be detectable in the cockpit of an unpressurized 727?

I kinda doubt it.

When I jumped from the airstair exit on an unpressurized DC 9 in 2006 I was surprised to feel pressure bumps from all those who exited ahead of me. I could have accurately counted the number of exiting jumpers with my eyes closed.

The stairs were removed but somehow a pressure spike was caused by each exciting jumper. If you listen carefully you can hear the acoustic "whoosh" artifacts here:

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Could the dummy parachute have been used as a projectile to simulate a jump?

Could D.B. Cooper have lobbed or hurled the dummy parachute as a projectile, targeted at the bottom end of the staircase of Flight 305, with sufficient impact force so as to simulate a jump?

(for reference, please see my original hypothesis, graciously posted on my behalf by Bruce A. Smith, as Reply #1688 on: May 02, 2017, 05:46:43 PM.)

I realize my hypothesis about the use of the dummy parachute comes close to heresy in standard Cooper lore, and there are probably a lot of very good arguments against it. Please, I’m not trying to step on anyone’s toes. I’m just asking, because I think it is an intriguing possibility, could this be a plausible use and scenario for the dummy parachute? I’d like to put my hypothesis out there, “for your consideration.”

Here are the dimensions for the stairwell, and for a hypothetical throw of the dummy parachute, as shown in the above diagram that I made by cropping and modifying and overlaying the original © Boeing diagram, as show on this site:

The stairwell is about 3 feet wide. The exit door is 6 feet 4 inches high. There is about 2 feet of headroom above the exit door. There are 16 steps (counting the top step,) and the hinge point of the stairway begins at step number 6, descending.

Based on several photos and diagrams I have seen and compared, I have estimated the dimensions of the interior of the stairwell as shown in this diagram. I overlaid those estimated dimensions on a portion of the schematic drawing of a side view of the stairway, as shown on this site.

Based on those specs, if Cooper used the dummy parachute as a projectile to try to simulate a jump, and he targeted the 14th step, then appears to me Cooper would have had to make a shot at a target about 17 feet 6 inches away. Cooper stood about 5 ft. 10 in. tall, so if he raised his arms overhead, he could have begun that overhead shot at a height of about 6 ft. 6 in. The shot had to hit the targeted 14th step (or close to it) about 13 ft out and 12 ft down from where the shot began.

The parachute weighed about 20 pounds. If it had dropped 12 feet in a free fall, it would strike the 14th step with about 240 foot-pounds of force. If Cooper actually “hurled” it downward, then it would have struck even harder. Either way, that is a significant force to impact the bottom of the stairway, and would have caused it to bend downward.

The parachute would strike the stairway at an angle, however, so it would still need to tumble down at least a couple more steps in order to impart as much of the downward impact force as possible, before it finally tumbled off the end. At which point the staircase would rebound, as it actually did, hard enough for the staircase to slam shut, which apparently it did.

In the diagram, I have shown a floating position for the stairway about midway between the extended position and the retracted position. I realize this would be variable at the time of the actual flight.

I’m not fully certain about the actual height of the ceiling panels in the stairwell, though I think it is fairly close to what I have shown in the diagram. But even if the ceiling panels were 2 feet lower, this hypothetical throw could still work. There is a large margin for allowable error as shown in this diagram for being able to make a successful hypothetical throw of the dummy parachute.

But would it be enough force, and would it be convincing for simulating a jump? Keeping in mind my stated assumption that Cooper was a commando, that is my question for the Forum, for your consideration.

“Could D.B. Cooper have lobbed or hurled the dummy parachute as a projectile, targeted at the bottom end of the staircase of Flight 305, with sufficient impact force so as to simulate a jump?”

Thanks and best wishes to all,  John S.

Hi John S. Am sure others will comment about this but I wanted to come back to your post because (a) great graphics - congrats! You have no idea how valuable good graphics are in explaining a person's ideas  ... picture worth a million words. (b) If I understand your concept, I think I do, the dummy chute would have lacked the 'mass' to have caused the impact you want .... at least that's my opinion.

A couple of facts might help. 1. those stairs are the 'jaws of death'. They want to snap back in a milli-second and that was measured using the chase plane photos during the test. Part of that closure effect is due to the hydraulics of the stairs combined with hi velocity air flowing underneath the stairs when the plane is in motion. 2. It took considerable mass (200 lbs) to get the stairs to lower in flight. That dummy chute was only a fraction of the weight needed to get a reaction out of the stairs. 3. There is nothing in the flight comms that indicates multiple periods of oscillations and bumps, plural. The crew was monitoring those effects very closely once they started because they knew they related to the stairs being deployed, someone being on the stairs, and someone probably bailing with weight off the stairs and the stairs snapping back shut closing the rear hole and causing a pressure spike or a Bernoulli Effect.

Maybe R99 and Shutter have opinions - hope so. But a very good post - what other ideas do you have?

Shutter wrote: "wouldn't that jump be different, you guys take a dive through an opening breaking a barrier, or disrupting an opening. the stairs would of done that, but would Cooper leaving them?"

Good point Shutter.

But still, I doubt if DBC knew there was anything that needed spoofing. It's not obvious that a door/stairs/ramp moving outside of an unpressurized cabin would be detectable in the cockpit. It's not like a plunger or piston which is inserted into a cylinder.

One could possibly spoof the exit by bouncing on the lower part of the stairs, slowly ascending to a higher level where the moment arm is lower, WAITING, and then, while facing forward, pull the ripcord and be lifted off the stair by the squidding canopy.

Still, I don't think DBC saw a need to spoof anything.

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It kind of depends on his experience, which we may never know. There is nothing to indicate that he cared one way or the other once he decided to be gone of the airplane! My feeling is wanted to flee the area where he jumped as soon as possible. 

Question on parachutes

We are in the midst of envisioning new ideas, such as Flyjack's pondering on a money separation on the airstairs. In that spirit, I propose another notion:

Can a skydiver actually wear two parachutes on their back - one underneath the other?

Obviously, Cooper didn't do that with the two back chutes since the second Pioneer was found intact on 305. But could the reserve chute, with money, be worn underneath the Pioneer/Steinthaul somehow?

Or could the reserve bag be tied around Cooper's torso with cords from the other reserve, and then filled with money - and all of it underneath the back chute? DBC spent a lot of time at the back of the plane before he jumped. Was he re-fitting himself and his parachutes?

There is another option...

It is common for the FBI to withhold information from the public to have details that only the hijacker would know. We have had docs released over the years but that doesn't preclude the FBI from holding back some. We just can't assume that the info we have is complete and logically incomplete info can't be used to negate.

Also RE: Tie particles.. another potential source for found CPTi, SS300 and SS400 (Stainless Steel)

Discovered that CPTi (Commercially Pure Titanium) was used in dentistry (implants) in the late 1960's.

300 series SS - 500 pieces found - was also used in dentistry (implants)
400 series SS - 150 pieces found - was used for dentistry tools, less corrosion resistant

The particles may have come from Dental work while the hijacker was wearing the tie.


These were also used on the 727..