Re: Lost in the caribbean
Larry Dighera
<7d6729ec-4528-43ae...@j2g2000vbo.googlegroups.com>:
>Hello to all,
>
>I am searching for details of an incident that occured back in the
>early eighties. A light aircraft got lost in the caribbean. The pilot
>eventually made radio contact on 121.5 with an airliner. The captain
>managed to find the lost pilot by finding their relative position
>using the sun's bearing and the captain decided to pinpoint himself to
>the lost pilot by jettissoning fuel making a contrail. Happily they
>found each other and the airline captain provided "vectors" to the
>lost pilot to a nearby island.
>
>No joy using Google. Details would be appreciated should anyone
>remeber this one. I am teaching young pilots the rudiments of
>navigation and the reasonning for learning old methods...
>
>Cheers
>
>Marc Arsenault
Perhaps this is the incident to which you refer:
http://www.navworld.com/navcerebrations/mayday.htm
“Mayday mayday.” This message of a pilot in distress on radio three
days before Christmas 1978 is heard by Auckland ATC. The saga of how
Jay Prochnow was finally located by the innovative navigational
techniques of Captain Gordon Vette aided by Malcolm Forsyth both of
Air New Zealand, Auckland ATC, Norfolk Island and the crew of the
Royal New Zealand Air Force (RNZAF) Orion is made into a Brain Game.
The Penrod, a towed oil rig with running lights, served as a beacon
which enabled Captain Vette to rendezvous with Jay Prochnow.
The Sun reached its highest ascension 21 December 1978 at the winter
solstice (summer in the Southern Hemisphere) and the very next day Jay
Prochnow (a former U.S. Navy pilot), piloting a Cessna 188 AgWagon
found himself lost. He was ferrying the Cessna from Pago Pago to
Norfolk Island. With a failed ADF and an overdue ETA, he was deeply
worried.
Prochnow began an expanding square pattern hoping to find Norfolk
Island before the fuel ran out. Capt. Gordon Vette in command of an
Air New Zealand DC-10 (equipped with three inertial navigation
systems), believed to be near the Cessna, was enlisted by Auckland ATC
to help locate the lost Cessna. Vette, a qualified navigator,
contacted Prochnow and asked him to head toward the Sun and to report
his magnetic heading. Prochnow pointed the Cessna to magnetic heading
274 degrees as Vette steered his DC-10 toward the Sun and read his
magnetic heading as 270 degrees. Next Vette instructed Prochnow to
determine the elevation angle of the Sun above the horizon using his
partially outstretched arm and fingers as a sextant. Prochnow
established the elevation of the Sun as four fingers as Vette measured
the elevation of the Sun as two fingers. Vette estimated the Cessna
was about 240-250 nmi (each finger was slightly more than 2 degrees
with each degree worth 60 nmi) from the DC-10. Vette was then able to
get within VHF boxing range of Prochnow in 7 or 8 minutes. Prochnow
was directed to fly east toward the DC-10. The Sun began to set.
Norfolk Island and Prochnow were both instructed to note the time that
the upper limb of the Sun sank below the horizon. With this
information, the results of VHF radio reception (contact/loss) and the
time of sunset comparison observed at Norfolk Island and the Cessna,
the Cessna’s position was determined to be within 290 miles of its
destination. Rendezvous over a towed ocean rig refined the position
and Prochnow was directed to a heading to intercept Norfolk Island. We
may conclude that the Cessna was:
a. Northeast of the DC-10 initially and located by using sunset
tables adjusted for altitude and VHF reception
b. Southeast of the DC-10 initially and located by using sunset
tables unadjusted for altitude and VHF reception
c. Southwest of the DC-10 initially and located by using sunset
tables adjusted for altitude and VHF reception
d. Northwest of the DC-10 initially and located by using sunset
and declination tables adjusted for altitude and VHF reception
The answer is:
In constructing this Brain Game certain liberties were taken regarding
details of air-to-ground-to-air coordination. However, the concepts
of location finding portrayed are based on the valid techniques
employed by the DC-10, Norfolk Island, Aukland ATC and the Cessna.
Space limits including all the details of the crisis confronted by
Prochnow and all the refinements employed in the search. Since the
heading of the Cessna to the Sun was 274 degrees it was greater than
the 270-degree heading of the DC-10, that meant that the Cessna was
south of the DC-10 as shown in Figure 20 . Since the elevation angle
of the Sun measured by Prochnow was higher than that established by
Vette, the Cessna was closer to the Sun or west of the DC-10 as shown
in Figure 21 . Thus, the Cessna was southwest of the DC-10.
Vette recognized that the VHF communication link could be exploited to
locate the Cessna. He requested that the Cessna orbit as he raced
through the VHF range circle which had a radius of about 200 nmi as
depicted in Figure 22 . A map of the region, courses, and events is
depicted in Figure 23 .
Capt. Vette reasoned that if he marked the points at which he
established and lost contact with the Cessna, he could find the
location of the Cessna. He knew the diameter of the VHF range circle
was 400 nmi He flew his DC-10 along track 1-2 as depicted in Figure
24 . He acquired VHF contact at point 1 and lost VHF contact from the
Cessna at point 2 (marking the point) at which time he turned 90
degrees left and began his aural box pattern. After flying on this
new leg for a reasonable period, he
Figure 20. Cessna South of the DC-10
Figure 21. Cessna Must Be West of the DC-10
Figure 22. VHF range
Figure 23. Map of Mayday in December
Figure 24. Flying the Aural Box Pattern into the VHF Range Circle
turned 90 degrees left for a short period followed by another 90
degree turn to the left and at point 3 he regained VHF contact with
the Cessna (as he marked his map). He continued through point 4 where
he lost VHF contact with the Cessna. Using the intersection of the
perpendicular bisectors to the two chords flown within the VHF range
circle, Capt. Vette established the center and the location of the
Cessna. The Cessna, however, was not immediately found. Earlier, the
DC-10 had dumped fuel to leave a trail which was not seen by Prochnow.
Capt. Vette recognized that one can determine the difference of
longitude between Norfolk Island and the Cessna by noting the GMT of
sunset at the two locations. Norfolk’s local time was 1900 for this
event. The Cessna’s time was reduced to sea level (as Prochnow would
see sunset later owing to his altitude and his eastward displacement
from Norfolk Island). The difference between the times in GMT for
sunset at the two observations was 22.5 minutes which corresponds to
5.6° longitude (a degree is equal to 4 minutes in time). Norfolk’s
coordinates were latitude 30°S, longitude 168°E. This would place the
Cessna at longitude of 173.6°E , 291 nmi east of Norfolk (5.6°x 60
nmi/deg x cos 30°). Prochnow was directed to fly northwest during
this interlude as he was regarded as being southeast of Norfolk
Island. A RNZAF Orion was dispatched to help find the Cessna which
had been airborne for 20.5 hours and now had minimum fuel remaining.
Continued plotting by the navigators showed that the Cessna was
approximately at 30°S, 171°E. Prochnow soon saw a light on the
water’s surface. Prochnow found an oil rig under tow whose
coordinates (31°S, 170° 21'E) were relayed to the DC-10 and enabled a
rendezvous with the Cessna. The Cessna was less than 150 nmi from
Norfolk and was given a steering direction by Vette of 294° magnetic
heading to Norfolk Island. The Cessna landed safely after being
airborne 23 hours and 5 minutes arriving at close to midnight 8 hours
beyond its 1600 ETA. Prochnow had stretched the Cessna’s twenty-two
hours of fuel by 5 percent through cruise control.
Sources of error
Aural boxing. Depends on continuous transmission on VHF otherwise a
silence can be construed as loss of contact. To be accurate the
acquisition and loss of Prochnow’s VHF trans-missions would have to be
accurately noted. There could
be timing errors in this procedure in noting these events (30 seconds
error in the same direction on each end contributes to 10 nmi error at
600 knots ground speed).
Sunset observation. Accurate determination of longitude by observing
time of sunset requires knowledge of latitude by observing sunset and
noting the time in GMT one may determine longitude by assuming a
latitude of the site.
The Local Mean Time of sunset changes 13 min/5° latitude in this
region of 30°latitude. Therefore, an error of one degree latitude
contributes to 2.6 minutes in time error which is 2.6 min x 1°/4 min
or 0.65° of longitude uncertainty or 0.65° x 60 nmi/°
x cos 30° or 0.65 x 60 x 0.866 = 33.8 nmi error in longitude which
demonstrates that determining longitude by assuming a latitude is very
sensitive to the latitude assumption.
Afterword
Captain Vette had dumped fuel when he thought he was within visual
contact of the Cessna. He believes that the Cessna’s opaque canopy
prevented Prochnow from sighting the DC-10. Vette concluded that his
dump position was behind the Cessna as verified from his inertial
navigation coordinates and an HF line of position.
=============================================
http://books.google.com/books?id=BD9a12eG0okC&lpg=PA213&ots=6ipLtHQeTF&dq=jay%20prochnow%20gordon%20vette&pg=PA213#v=onepage&q=jay%20prochnow%20gordon%20vette&f=false
Captain Gordon Vette and the Rescue of Jay Prochnow
http://www.amazon.com/Human-Contribution-James-Reason/dp/0754674029/ref=sr_1_1?s=books&ie=UTF8&qid=1284817085&sr=1-1#_
At 5.30 pm on december 21st 1978, a DC-10 piloted by Captain Vette, on
its > way from Fiji to Auckland, received a report of a missing light
aircraft. The > pilot was lost somewhere in the South Pacific in the
vicinity of Norfolk > Island without navigation aids, low on fuel and
night approaching. By > skillful deductive methodologies of navigation
and radio range, Captain Vette > and his crew located the light
aircraft and effected a rescue, with little > more than a sniff of
fuel left in the rescued aircraft’s tanks. The aircraft > only had
enough fuel for 22 hours and landed after 23. Captain Vette was >
awarded the Johnston Memorial Trophy.
http://www.imdb.com/title/tt0107556/plotsummary
Plot Summary for
Mercy Mission: The Rescue of Flight 771 (1993)
http://airodyssey.net/1999/03/01/movie-flt771/
Mercy Mission: The Rescue of Flight 771 (Movie review)