NavList:

I went to plot these courses on my Miami Sectional and found that I had 
already plotted the courses of Flight 19 several years ago, but I 
noticed a difference. The first course I had plotted is 097ºT not the 
091ºT in your post. I don't remember where I got the course that I had 
plotted years ago. But, with the legs I had plotted in the past the 
three legs do take you back to Ft. Lauderdale. The end of the second leg 
is right over Great Stirrup Cay.

But there is yet another mystery. The planes were supposed to have 
practiced bombing on a ship wreck. That wreck is the ship Sapono. The 
problem is that the Sapona is 25.6 NM SSW of Great Issacs, I know 
because I have dived upon it. Its location is 25º 30.1' N, 79º 17.6' W'. 
I am attaching a photo from Google Earth of the ship.

Here is a link to more information about the ship.

So is there a different ship that they were to bomb? If not then why 
didn't the nav problem give an accurate course to the Sapona? If they  
took their departure from the Sapona for the second leg then the 
successive courses would take them back quite a bit south of Ft. Lauderdale.

Any ideas?

gl





Paul Hirose wrote:
  

This is about the "Bermuda Triangle" incident in December 1945, when
five U.S. Navy torpedo bombers took off from Florida on a training
mission and disappeared. I don't have any new insight on what happened,
just some comments on the intended route.

The Wikipedia article
(http://en.wikipedia.org/wiki/Flight_19#Authorized_overwater_navigation_training_flight) 


says, "With a trainee pilot in the role of leader out front, the
exercise was called 'Naval Air Station, Fort Lauderdale, Florida,
navigation problem No. 1,'[1] and it involved the Avengers negotiating a
triangular course from and returning to Fort Lauderdale. After take off
they would fly almost due east for 56 miles (90 km) until reaching Hens
and Chickens Shoals where bombing practice was planned. The flight was
then supposed to continue east another 67 miles (108 km) before turning
onto a course of 346 for 73 miles (117 km), in the process over-flying
Grand Bahama Island. Finally, Flight 19's last turn was a course of 241
degrees for 120 miles (193 km), bringing it back to NAS Ft. Lauderdale.[2]"

Footnote [1] is a Web page which appears to be an excerpt from the Navy
investigation report. The pertinent part says,

"2. That the organized overwater navigation training flight assigned to
Flight 19 on 5 December 1945 was Naval Air Station, Fort Lauderdale,
Florida, navigation problem No. 1 is as follows; (1) depart 26 degrees
03 minutes north and 80 degrees 07 minutes west and fly 091 degrees (T)
distance 56 miles to Hen and Chickens Shoals to conduct low level
bombing, after bombing continue on course 091 degrees (T) for 67 miles,
(2) fly course 346 degrees (T) distance 73 miles and (3) fly course 241
degrees (T) distance 120 miles, then returning to U.S. Naval Air
Station, Fort Lauderdale, Florida."

It's a safe bet that a Navy report would use nautical miles. Therefore,
the Wikipedia article should say "nautical miles", not simply "miles",
and use the correct conversion to kilometers. Also, the courses should
be clearly identified as true courses, as in the Navy document.

Another problem is not so obvious: the triangular route doesn't close on
itself. I discovered that when "flying" it in Microsoft Flight
Simulator. Despite using the autopilot to hold headings, and even
turning early by a calculated amount at each course change to allow for
the finite turn radius of the plane, I finished about 10 miles from the
departure point.

N26°12.7' W080°08.8'  sim result, first flight
N26°11.8' W080°10.2'  sim result, second flight

In these flights I simply combined the first two legs into one. I.e., 
the combined leg was 123 NM nonstop on TC 091, no bombing practice in 
the middle.

My first theory for the failure to connect to the departure point was 
inaccuracy in the sim, so I computed the end point of the route two 
different ways:

N26°13.6' W080°07.4'  Mercator sailing
N26°13.6' W080°07.4'  Lambert grid

These computations confirm the flight simulator result. Flying the
correct courses and distances puts you 10.6 miles away at a bearing of
358° from the departure point.

I believe that was intentional, to show the students a classic dead
reckoning landfall technique. By aiming definitely north of the
destination they could simply turn south at landfall, follow the coast,
and be sure of getting home. There is no doubt the route worked, since 
many students successfully flew it, including another flight the same day.

The navigation exercise waypoints:

N26°03.0' W080°07.0'  departure point
N26°02.0' W079°04.8'  Hen and Chickens Shoals
N26°00.8' W077°50.4'  turn to 346° true
N27°11.9' W078°10.1   turn to 241° true
N26°13.6' W080°07.4'  end

Except for the first (which comes from the Navy report), I calculated
those points on both a Mercator grid and a Lambert conformal conic grid,
the latter with standard parallels N25°20' and N30°40'. At every point
the results agreed within .001°.

The coordinates for the end of the first leg (Hen and Chickens Shoals) 
are within a mile northeast of Great Isaac Island, with its big lighthouse
(http://www.biminisands.com/bahamas/island/great-isaac-lighthouse.htm).
And four miles southwest of the island is the concrete ship SS Sapona,
wrecked in a 1926 hurricane
(http://www.concreteships.org/ships/ww1/sapona/). I suspect Flight 19
"attacked" the hulk, used Great Isaac Island as their departure point
for the 67 NM leg on true course 091, then became disoriented after the
turn to TC 346.

If they had started the second nav leg from SS Sapona instead of the 
island, that would have offset the rest of the flight a few miles to the 
south, and put the end point closer to the airfield. This may very well 
have been the intent of the exercise.

However, my calculation assumes the second leg began where the first leg 
ended.

All that is a lot to say about a trivial anomaly in an old Navy 
navigation exercise, but as far as I've seen nobody has ever pointed out 
that the route (depending on how you interpret the directions) can fail 
to close on itself by 1 part in 30. And since I did all this work, it 
may as well be preserved on the Web.

Before I say anything on the Wikipedia Flight 19 talk page, I'll see if
anyone here has any comments.

  
    

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