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DB Cooper

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(edited)
4 minutes ago, Chaucer said:

Right, but not only opening the door, but also lowering the stairs and climbing out on them in-flight would also cause changes that would have been felt by the crew.  And the oscillations were continuing between 8:10 and 8:12; therefore, the "pressure bump" had to have occurred after 8:12. 

Maybe. But if you trust Flyjack's speed numbers, the plane was increasing in speed after 812. If Cooper had jumped at 812 or later, this would not happen. Hard to say for sure. I would guess that at 811, when the cabin pressure needle takes a big jump up and down...the so called pressure bump...that this would be caused by the stairs snapping back up after Cooper jumped. Even if you give an extra minute to account for discrepancies in the transmission and communications process, this still puts the jump at no later than 812. 

Edited by RobertMBlevins

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(edited)
10 minutes ago, Chaucer said:

Right, but not only opening the door, but also lowering the stairs and climbing out on them in-flight would also cause changes that would have been felt by the crew.  And the oscillations were continuing between 8:10 and 8:12; therefore, the "pressure bump" had to have occurred after 8:12. 

Door was opened much earlier, so not that.

It is right here... pressure bump = gauge change

Gauge before oscillations

Therefore pressure bump before oscillations.

 

oscillations1.jpeg.0a12aaf5ed83518107c67def3d48107e.jpeg.95c5865a1424c51a4a91824dd505c512.jpeg

 

Edited by FLYJACK

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(edited)
4 minutes ago, FLYJACK said:

Door was opened much earlier, so not that.

It is right here... pressure bump = gauge change

Gauge before oscillations

Therefore pressure bump before oscillations.

 

oscillations1.jpeg.0a12aaf5ed83518107c67def3d48107e.jpeg.95c5865a1424c51a4a91824dd505c512.jpeg

 

I don't believe it's the same thing. All other evidence points to the oscillations leading to the pressure bump. 

Again, there is confusion between the oscillations occurring at 8:11 and the pressure bump which did not. 

Edited by Chaucer

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2 minutes ago, Chaucer said:

I don't believe it's the same thing. All other evidence points to the oscillations leading to the pressure bump. 

They are the same thing.. the pressure gauge change was the pressure bump.. the oscillations continued after the bump..

There is no other evidence... what evidence?

Do you think the stairs rebound up stop and don't oscillate?

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(edited)

The statements from Anderson and Rataczak would disagree. 

56 minutes ago, FLYJACK said:

They are the same thing.. the pressure gauge change was the pressure bump.. the oscillations continued after the bump..

There is no other evidence... what evidence?

Do you think the stairs rebound up stop and don't oscillate?

The statements from Anderson and Rataczak would disagree with that assessment. Here is what Anderson had to say:

"...it wasn’t a one time event but a series of fluctuations which attracted our attention.  I saw it first then alerted Scott and Bill, ending in a single pressure event we felt in our ears, and nothing following, not even more fluctuations. We waited to see if something more would happen but it didn’t."

"These were minor oscillations. We detected on the guages only. We just presumed pretty quickly that it was Cooper fiddling with the aft stairs but we weren’t one hundred percent sure because we were already flying dirty, with throttles up and fighting icing and weather. A lot going on and it wasn’t totally smooth even before the oscillations started. What we noticed was the pattern of the oscillations was continuing and there was a very minor disruption of the slipstream. Scott said at first he wasn’t feeling anything for sure, then a little later he thought there was more drag and the nose was deviating a little. When the final bump happened and the oscillations stopped that sealed it. But even then we weren’t sure and we waited before calling anybody."

"I monitored the guages and reported to Captain Scott.  We all agreed that the guages were detecting a disruption of airflow, most likely caused by Cooper testing out the aft stairs.   But we all felt one physically distinguishable "bump" with our ears which came abruptly after we had been monitoring the gauges. We all felt it said almost in unison, surprised, "there he goes!"  It was the largest bump by far, an abrupt pressure change.  We all thought he had exited the aircraft at that point, because the guages never detected any further major airflow disruptions after that ‘thud’. The re-test duplicated the oscillations and the pressure bump exactly. "

 

Edited by Chaucer

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Chaucer: The disruption of airflow begins when Cooper first drops the stairs. From that point on, there is going to be some vibration throughout the aircraft, due to the change in the flight characteristics caused by the stairs disrupting normal airflow at the tail of the plane. This is why it started, and continued even after the 'final' or 'big' bump occurred. The bump was Cooper jumping off the stairs. 

Rataczak has described the pressure bump as a change in air pressure that makes your ears pop. Everyone on the flight deck realized what had just happened. Cooper jumped. The stairs rebounded back up like jumping off a diving board. The cabin pressure gauge jumps. I guess the point here is WHEN on the timeline did this bump occur. It's tricky to narrow down, because of the slight inaccuracy between cabin crew reaction, transmissions by radio, the recording time stamp on those transmissions, and other factors. But 811 seems to be the confirmed time it happened. 

Also, the speed numbers put up by Flyjack support this same idea. And Rataczak said the same exact thing happened with the sled drop test. After Cooper jumps, there will be some normal vibrations coming from the tail area due to the stairs being left to hang out a couple of feet below the aircraft. They did scrape on the ground a bit upon landing in Reno, although there was no serious damage. Truth is, no on the flight deck knew for sure what would happen when they landed. Should the tail really drag hard on the tarmac, the jet could have easily cartwheeled and crashed. They were lucky. 

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(edited)
2 hours ago, Chaucer said:

And my point is that the oscillations ended when the bump occurred. The bump can’t occur if the oscillations are still ongoing.


You can’t give birth and still be pregnant.

What do you believe will happen with a 727 with the airstairs hanging down a couple of feet from the tail area? There will be vibrations, oscillations, whatever you choose to call them. Since the stairs were opened and these things began happening, just because the stairs return to a state of being below the aircraft a bit...this does not mean the initial oscillations will go away. They will just become less than they were, and the aircraft will be able to increase its speed a bit. This is exactly what was going on. 

They started because...the door was opened. 
The speed of the aircraft dropped because....someone went out on the stairs, forcing them down and increasing the drag on the aircraft. At this point speed dropped to its lowest level. The oscillations of course, became worse. 

There was a heavy bump when Cooper's weight was no longer on the stairs, and the stairs went upward again, settling to a point about 2-3 feet under the tail. The speed of the aircraft increased because the drag was less. 

The vibrations lessened as well, but continued all the way to Reno. The plane managed to land safely. 

Edited by RobertMBlevins

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21 minutes ago, RobertMBlevins said:

Let's do some pictures for illustration:

 

Bump1.jpg

Bump2.jpg

Bump3.jpg

Bump4.jpg

FYI:  The Sled Test Drop got the same results. 

I'm not disagreeing with anything you have posted here except that I can't comment on the speed change because I haven't looked into. Regardless, I'm talking about time. The oscillations and fluctuations occurred first, and ended with the bump. According to Anderson, the oscillations and fluctuations did not occur again after the bump.

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(edited)
4 hours ago, Chaucer said:

The statements from Anderson and Rataczak would disagree. 

The statements from Anderson and Rataczak would disagree with that assessment. Here is what Anderson had to say:

"...it wasn’t a one time event but a series of fluctuations which attracted our attention.  I saw it first then alerted Scott and Bill, ending in a single pressure event we felt in our ears, and nothing following, not even more fluctuations. We waited to see if something more would happen but it didn’t."

"These were minor oscillations. We detected on the guages only. We just presumed pretty quickly that it was Cooper fiddling with the aft stairs but we weren’t one hundred percent sure because we were already flying dirty, with throttles up and fighting icing and weather. A lot going on and it wasn’t totally smooth even before the oscillations started. What we noticed was the pattern of the oscillations was continuing and there was a very minor disruption of the slipstream. Scott said at first he wasn’t feeling anything for sure, then a little later he thought there was more drag and the nose was deviating a little. When the final bump happened and the oscillations stopped that sealed it. But even then we weren’t sure and we waited before calling anybody."

"I monitored the guages and reported to Captain Scott.  We all agreed that the guages were detecting a disruption of airflow, most likely caused by Cooper testing out the aft stairs.   But we all felt one physically distinguishable "bump" with our ears which came abruptly after we had been monitoring the gauges. We all felt it said almost in unison, surprised, "there he goes!"  It was the largest bump by far, an abrupt pressure change.  We all thought he had exited the aircraft at that point, because the guages never detected any further major airflow disruptions after that ‘thud’. The re-test duplicated the oscillations and the pressure bump exactly. "

 

Now I remember that interview, vaguely, those statements are a fairly recent recall and some out of context. 

 

"When the final bump happened and the oscillations stopped that sealed it. But even then we weren’t sure and we waited before calling anybody. "

The interview confirms the other evidence that the crew reported the "bump" late... there was a delay. That undermines the assertion that the bump was after 8:13. Then the bump oscillation sequence becomes moot. The minor oscillations on the gauge started well before.

It was 8:11. The recording was analyzed.

pressoscilltion.jpeg.3b4ef4df5f00f64506cd6ca1f5d48d9e.jpeg

 

It may be semantics. Anderson is referring to his gauge oscillations. 

"Not really and it wasn’t exactly as you describe.  These were minor oscillations. We detected on the gauges only. "

It is clear there were very "minor oscillations" not felt but seen on the rate of climb gauge before the bump. This was confirmed in the test. "very little"

gauge2.jpeg.080e1edb1243f66a4102ba1e269ab701.jpeg

 

 

 

The bump was seen on the pressure gauge. I didn't realize there were two different gauges.. 

pressuredrop.jpeg.850194222de386b85ff985fa9f0d4e2c.jpeg

 

They didn't fully realize it was Cooper..

"We just presumed pretty quickly that it was Cooper fiddling with the aft stairs but we weren’t one hundred percent sure because we were already flying dirty, with throttles up and fighting icing and weather."

 

There were more bumps or one?  or were those oscillations? no further MAJOR airflow disruptions. What about minor ones?

"We all agreed that the gauges were detecting a disruption of airflow, most likely caused by Cooper testing out the aft stairs.   But we all felt one physically distinguishable "bump" with our ears which came abruptly after we had been monitoring the gauges. We all felt it almost in unison, surprised, "there he goes!"  It was the largest bump by far, an abrupt pressure change.  We all thought he had exited the aircraft at that point, because the gauges never detected any further major airflow disruptions after that ‘thud’. The re-test duplicated the oscillations and the pressure bump exactly. "

 

That interview is important but it still isn't clear when these guys are are referring to oscillations, fluctuations, disruptions or whatever.. felt or seen on gauges..  Anderson is clearly referring specifically to the minor oscillations on his rate of climb gauge which had been occurring for some time. He states those oscillations ended after the bump. I believe that was not immediate but when the stairs stopped undulating, that may be brief. He also said no more major oscillations,, what does that mean? they were described as minor.. did they continue on his gauge.. were they describing the bump as a major oscillation?

 

 

The ear plug coming out is from the pressure bump.. an increase in pressure = door closing..

earplug.jpeg.28c606c2814a69d9649a9a83126d1977.jpeg

then "we're are getting some oscillations"...   bigger ones? minor ones were occurring for a bit..

bumposl.jpeg.5833f85b598c44892d500fff69d322da.jpeg

 

 

 

Edited by FLYJACK

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Yes, but even at 8:12 the crew typed a message on the teletype and only mentioned oscillations, not a bump. Also, Larry Carr later determined that the crew WAS NOT on the phone with NWA at the moment the pressure bump happened. The reported it later. So, the 8:11 time would not be accurate. The incident with the ear piece was determined NOT to be the same thing as the pressure bump. 

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46 minutes ago, Chaucer said:

Yes, but even at 8:12 the crew typed a message on the teletype and only mentioned oscillations, not a bump. Also, Larry Carr later determined that the crew WAS NOT on the phone with NWA at the moment the pressure bump happened. The reported it later. So, the 8:11 time would not be accurate. The incident with the ear piece was determined NOT to be the same thing as the pressure bump. 

The crew didn't type any messages.  The crew only communicated by radio and it was the ARINC ground station that typed the teletype messages.

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20 minutes ago, Robert99 said:

The crew didn't type any messages.  The crew only communicated by radio and it was the ARINC ground station that typed the teletype messages.

Regardless, it doesn't change my overall point: The crew communicated "oscillations" at 8:12, not "pressure bump". 

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I'm going to re-type a key part of the FBI document, add some missing punctuation, but leave the original words in place. There are two minor additions for clarification, but nothing that changes the meaning of the document.

I will also highlight some words in it.

This is to make it easier to understand the main point of the document:

Quote

"There is a time correlation check on this tape, and through CAREFUL playback and sequencing (of) the time of oscillations caused BY THE AIRSTAIRS CLOSING after unsub departed, (this time of departure) was calculated at 8:11 PM."

That's pretty straightforward. What they are saying is that after they played back their time-correlated recording, they were able to pin down the time the airstairs bounced back up as a result of Cooper jumping from them. And that time was established as 8:11 PM. Even if you allow them a full minute error either way, this puts the jump at no later than 8:12 PM, and possibly sometime during the sixty seconds of the 8:10 mark. But no later than 8:12 and 59 seconds. 

The most likely scenario is that the 8:11 mark is accurate within sixty seconds inside that particular minute. 

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(edited)
9 hours ago, Chaucer said:

Regardless, it doesn't change my overall point: The crew communicated "oscillations" at 8:12, not "pressure bump". 

That time stamp in not precise enough...

Reviewing Anderson's interview there are some other problems..

He mentions minor oscillations on the gauge, then no more major ones..  (major and minor oscillations)

He mentions a final bump, a distinguishable bump, largest bump... (many bumps)

 

At the time the crew wasn't sure what happened all their perceptions of the event were formulated later.

 

My speculation is that there were minor oscillations and major oscillations described, those major oscillations were "bumps" until the final big "bump". In real time the crew wasn't distinguishing between bumps and minor gauge oscillations.. they did later.

The 8:09 FDR blob is a significant event.. it seems too early for the "pressure bump" but it might be and the times are off a bit..

But,

what if it was Cooper reaching the bottom of the stairs, pushing them down, trim adjustment.

Oscillations reported between 8:09-8:11 and jumps at 8:11.. (within a minute time variable)

 

Edited by FLYJACK

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9 hours ago, RobertMBlevins said:

I'm going to re-type a key part of the FBI document, add some missing punctuation, but leave the original words in place. There are two minor additions for clarification, but nothing that changes the meaning of the document.

I will also highlight some words in it.

This is to make it easier to understand the main point of the document:

That's pretty straightforward. What they are saying is that after they played back their time-correlated recording, they were able to pin down the time the airstairs bounced back up as a result of Cooper jumping from them. And that time was established as 8:11 PM. Even if you allow them a full minute error either way, this puts the jump at no later than 8:12 PM, and possibly sometime during the sixty seconds of the 8:10 mark. But no later than 8:12 and 59 seconds. 

The most likely scenario is that the 8:11 mark is accurate within sixty seconds inside that particular minute. 

I attribute this to the FBI’s confusion and conflation of two different events: the oscillations and the bump. I have no doubt the oscillations were happening at 8:11. The pressure bump happened at a later, unknown time.

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3 hours ago, FLYJACK said:

That time stamp in not precise enough...

Reviewing Anderson's interview there are some other problems..

He mentions minor oscillations on the gauge, then no more major ones..  (major and minor oscillations)

He mentions a final bump, a distinguishable bump, largest bump... (many bumps)

 

At the time the crew wasn't sure what happened all their perceptions of the event were formulated later.

 

My speculation is that there were minor oscillations and major oscillations described, those major oscillations were "bumps" until the final big "bump". In real time the crew wasn't distinguishing between bumps and minor gauge oscillations.. they did later.

The 8:09 FDR blob is a significant event.. it seems too early for the "pressure bump" but it might be and the times are off a bit..

But,

what if it was Cooper reaching the bottom of the stairs, pushing them down, trim adjustment.

Oscillations reported between 8:09-8:11 and jumps at 8:11.. (within a minute time variable)

 

I think the interview is rather clear that they were experience minor pressure fluctuations that were hardly distinguishable from the “dirty flying” except on the gauges. Then there was one last sudden BUMP which ended those pressure fluctuations and which the crew concluded was Cooper left the plane. The oscillations were reported between 8:10 to 8:12. Thus, the pressure bump had to occur after 8:12. 

You are right that these times are not precise, but a difference of merely two or three minutes means 5 to 10 miles difference in location. I’m not sure we can ever determine the precise jump time with the current information we have...

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3 hours ago, Chaucer said:

I think the interview is rather clear that they were experience minor pressure fluctuations that were hardly distinguishable from the “dirty flying” except on the gauges. Then there was one last sudden BUMP which ended those pressure fluctuations and which the crew concluded was Cooper left the plane. The oscillations were reported between 8:10 to 8:12. Thus, the pressure bump had to occur after 8:12. 

You are right that these times are not precise, but a difference of merely two or three minutes means 5 to 10 miles difference in location. I’m not sure we can ever determine the precise jump time with the current information we have...

"after 8:12" do you mean 8:12:01 plus... or 8:13:00 plus..

if the report was between 8:10-8:12, you have 360 seconds from 8:10-8:13, the reported oscillation and bump could have occurred within that time. We don't have seconds marked..  are the times rounded up or down or concatenated???

IMO, that 8:09 FDR mark is a significance event... marking something.

We have all run into this,, with the imprecise data/comms we can't determine the exact location, 

IMO, the highest probability is 8:11 plus or minus a minute.

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(edited)
Quote

'IMO, the highest probability is 8:11 plus or minus a minute...'

I agree with this conclusion. The playback of the tape, (probably over and over) with a time correlation going on it,  is how they came to the 811 time of the jump. 

One thing I have said about the jump itself is to imagine yourself in Cooper's shoes. 

Cooper finally gets the airstairs to open. At this time, minor vibrations caused by a change in the airflow begin. Cooper is probably surprised as heck to discover the stairs only drop between (according to Rataczak) 24-36 inches, instead of enough for him to start walking down them with his load. 

WTF is THIS? he probably thinks. That's not enough. So he turns around backwards and starts backing down the stairs slowly. (He could try leaning over and going forward that way, but if the stairs drop suddenly, he could pitch over and go right off the end of the stairs.) As he backs his way down, vibrations up front, ('oscillations' if you will) will come and go. It's Cooper's weight and progress down the stairs, versus the airflow trying to keep them up. The jet engines above his head are probably roaring bloody murder in his ears as well. The stairs drop as he descends.

When he reaches the end of the stairs, the added drag slows the jet to its lowest speed yet. Up front, the crew can tell *something* is going on. They already know the stairs are open. But there has been nothing significant yet...until the point where he finally jumps, or perhaps pulls the ripcord right on the end of the stairs and lets it pull him off the stairs after it inflates. One or the other, I suppose. 

But...at the point where his weight is released from these extended airstairs...the stairs basically snap back up toward the aircraft, nearly closing, and a sudden change in pressure is felt up front. Plus one heck of a big bump I would imagine. A 727 just isn't that large. It's not a Jumbo Jet. After much research, a lot of discussions, and an examination of that tape, it is determined that this snap-back happened at 811PM. Plus or minus one minute. 

But since the jet is covering ground at approximately one mile every twenty seconds, establishing a precise spot where law enforcement officers could search for Cooper is never exact. If they could have said, "He jumped at 8:11:28(seconds) PM" it would be different. Allowing for a one-mile drift in either direction, and with a minimum one-minute plus or minus error, it would still leave a search area of six miles by two miles...or twelve square miles. It could even be NINE miles (three minute window by one mile drift either direction) and a search area of 18 square miles. But the most likely is the jump occurred when the tape shows it did. 811. 

Even twelve square miles is a lot bigger search area than people think. SIX is a lot. Without a chase plane pilot seeing Cooper jump, that was as close as they were ever going to get. Advantage: COOPER. 

*The one-mile in either direction drift assessment was suggested by Mark M of Dropzone, aka '377,' an expert parachutist and Cooperland guy who has been in the sport more than 40 years. He estimated this number from a jump of 10,000 feet.*

Edited by RobertMBlevins

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(edited)

I did a very detailed analysis right along the flight path from 19:54 through 20:26, a 32 minute stretch... measuring each segment precisely and converting to miles, NM and speed..

Each minute mark was measured and longer 5 minute increments were measured to get a smooth data set as a check.

I found that the missing 20:04 time was made up by the adjacent marks, I compared the 19:59 to 20:05 and the radar sweep must have just missed that time. Since each mark can be off, the marks before the missing 20:04 made up for the missing mark by being longer. The missing 20:04 is not relevant.

Obviously each of the manual marks is not precise but over the course of the path any deviations get corrected. I followed the path and since it has a plotting error the result isn't exact, but it is very close.

The average was 3.49 Miles per Minute or 3.04 NM miles per minute..

I found that the GROUND SPEED from 19:54 to 20:26 averaged 210 MPH or 182.3 NM.

Does that sound about right.. for ground speed..

 

Rough calc/est, 165 KIAS X EST 1.20% = 198 less wind EST 15k =  about 183 kn

 

If I did that right the path seems to match NORJAK..

 

The reason the path is erratic is because it is a minute plot with a 0.5 mile error. It is not really a representative path, it is a smoothed plot. The minute marks were made manually and are not precise. There are only a few major timing mark outliers. 

165 is the min control KIAS for the F106, that eliminates the F106 from the flightpath as it would have had to fly at the min along the entire path from 19:54 and minute marks would be far more randomly spaced and variable if the F106 was doing circles or s turns. F106 = busted.

 

 

Edited by FLYJACK

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Flyjack,

I have done a similar analysis and I worked out a 135 nautical mile FBI flight path from 7:36 to 8:22. That works out to 2.93 nautical miles per minute or a ground speed of 176 knots. 

I agree that the missing 8:04 is simply a missed radar return. 

Regarding the 8:11 time:  that is the reported time of the oscillations. The FBI continually confused and conflated the two things, and that has led people today to do the same thing. There is no way to know if the oscillations ended at 8:12, but that is the last time they were reported by the crew. The pressure bump was never recorded or reported - at least in the public files. 

Even the FBI, after many years, realized this and moved the drop zone farther south to the Hockinson area. My guess is that it’s actually closer to the north bank of the Columbia. 

So, again, we need to clear up the confusion between the oscillations/fluctuations and the pressure bump. Two different things. Two different times frames. If you confuse the two, then you will end up thinking the pressure bump happened between 8:10 and 8:12. It didn’t. It happened after.

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I’ve noticed a discrepancy in the plotted FBI flight path. I was hoping someone might be able to provide an explanation.

There is point plotted to the northeast of Pearson Airport just outside of Vancouver. The next plot visible is the one adjacent to the I-5 bridge leading into Portland. The problem is that those two points are over 5 nautical miles away from each other which would require 305 to suddenly increase its speed to over 330 knots. A more reasonable explanation is that there is another missing minute. There should be a plot point midway between these two near where Marine Park is today. 

Any ideas?

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