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    Re: Amelia Earhart's aerial navigation
    From: Greg Rudzinski
    Date: 2009 Nov 19, 09:54 -0800

    Excellent post Gary. Thanks.
    
    A few more questions. The abrupt ending of voice radio transmission
    implies trouble. Is it possible that the batteries/magneto and or fuel
    pump failed then causing a ditch short of Howland on the LOP
    approach ? What were there chances without a life raft?
    
    Greg
    
    On Nov 18, 9:59�pm, Gary LaPook  wrote:
    > Greg Rudzinski asked:
    >
    > Maybe Gary can comment on the following:
    > 1. Time tick before departure.
    > 2. Sobriety of Noonan.
    > 3. Life raft.
    > 4. Radio antenna.
    > 5. Head winds.
    > 6. Celestial opportunities.
    > 7. Sleep deprivation.
    > 8. Was it possible to fly right over Howland Island and not see it?
    > 9. Was Howland charted correctly.
    > 10.What would have been a better less risky route?
    >
    > Gary wrote:
    >
    > Fred may have had a drinking problem but many people with such a problem
    > manage to show up sober for work on Monday mornings because their jobs
    > depend on it. Noonan had an even greater reason to show up sober, his
    > LIFE depended upon it. They landed in Lae on June 29th. The night they
    > arrived in Lae he went out drinking with Collopy and Heath and they got
    > toasted. Collopy took him back to his hotel about midnight and Noonan
    > was wobbly. On the 30th work was done on the plane and they attempted to
    > get a time signal so that they could leave on July 1st but were not able
    > to get the radio time signal so they had to delay the departure one day.
    > On July 1st Noonan turned down an invitation to go out again with
    > Collopy and went to the radio office where they finally got the time
    > signal at 10:20 p.m. Earhart and Noonan were back in their hotel by 11
    > p.m. so no bender the night before departure. They took off at 10:00
    > a.m. the next day, July 2nd and the flight lasted over twenty hours.
    > Even if Fred had had to be poured into the plane (and the movie of the
    > departure shows him steady as he got into the plane) he would have had
    > plenty of time to sober up on the way to Howland. Because of all this it
    > is very unlikely that any drinking problem Fred may have had contributed
    > to the disappearance. This story was pushed to put the blame on Fred and
    > totake the focus off of AE's actions.
    >
    > I have posted the following before on another forum and it will answer
    > some of the questions.
    >
    > "Paul, I for one never believed that Noonan made a navigational error.
    > He was too experienced, too motivated (his life was on the line) and
    > the techniques being used were well proven and of sufficient accuracy
    > to have allowed them to find Howland."
    >
    > There is a lot of evidence that he was careful and competent. I think
    > all the stories that came out after the flight besmirching him
    > personally and his abilities were for the purpose of exonerating the
    > popular and well known American heroine celebrity AE from fault for the
    > disappearance, Fred was made the fall guy since he was an unknown nobody.
    >
    > I posted before that Fred would have been motivated to do a very
    > competent job on this leg since it was the sole reason that he was
    > brought along. Further proof of that was written by AE in "Last Flight"
    > ( the book written by AE as she went around the world and sent back
    > prior to her last flight),
    >
    > �"Fred Noonan has been unable, because of radio difficulties, to set his
    > chronometers. Any lack of knowledge of their fastness and slowness would
    > defeat the accuracy of celestial navigation. Howland is such a small
    > spot in the Pacific that every aid to locating it must be available."
    >
    > They had to delay the flight for a whole day so that �Fred could get a
    > radio time signal (it was broadcast only once a day and there was
    > interference the first day) so he could check his chronometers to
    > determine how fast or slow they were. This would not have been necessary
    > if they were just planning to use radio bearings to find Howland.
    >
    > This necessity for very accurate time is probably not understood by most
    > people on this forum. The earth turns at a rate of 900 knots (900
    > nautical miles per hour, or 1035 mph) at the equator which means that it
    > turns one nautical mile every four seconds. Without getting into the
    > details of how celestial navigation computations are done, it works out
    > that if your chronometer (a very accurate clock) is slow by just four
    > seconds then your celestial computations will place you one nautical
    > mile further west than where you actually are. If it is fast then you
    > will think you are east of where you actually are. It doesn't take too
    > many seconds of unknown chronometer error to cause you to miss Howland
    > if using only celnav. Since their course was mainly eastbound they only
    > had to be sure that they did not pass too far north or south of Howland
    > so as to be beyond the range of Itasca's transmitter. Precise longitude
    > would not have been needed if they planned to just use the radio
    > direction finder for final guidance to the island. Since they were
    > willing to wait a whole day just to get an accurate time check it shows
    > that they planned to have celnav at least as a backup to radio direction
    > finding and knew that they would need the maximum accuracy possible in
    > that eventuality.
    >
    > If they were just going to use radio bearings then AE didn't need Fred,
    > she could do that herself since the radio equipment was in the cockpit.
    > It is obvious, then, that the entire world flight was planned around the
    > need to use celestial to find Howland.
    >
    > I had also posted that Fred would have pre-computed the landfall
    > procedure so that it could be easily accomplished after a long and
    > tiring flight. I believe that he would have done this on the ground
    > before takeoff either that morning or the day before or early in the
    > flight before becoming fatigued. These computations would have only
    > taken about one hour using Dreisonstok and plotting the �altitude curve
    > on graph paper for the sun's and moon's altitudes as calculated at
    > Howland. With this pre computed he could take many shots with his
    > sextant and compare the measured altitudes with those on the graph and
    > know instantly if they were staying on the LOP to Howland. No further
    > complex computations would need to be done in flight while approaching
    > the island.
    >
    > Even if they were planning to use a radio bearing to find Howland and
    > celestial was planned only as a backup Fred would have known not to
    > count on the radio working since it had failed them approaching Dakar.
    > In fact he didn't have to think back that far. The day before the last
    > flight they had had their radio repaired and had test flown the plane to
    > check out it's operation. They were unable to get a null which meant
    > that the radio direction finder WAS NOT WORKING. For some inexplicable
    > reason they ignored that blatant fact and decided that the reason they
    > could not get a null was that they were too close to the station.
    > Certainly Noonan appreciated this was at least a potential problem and
    > would have redoubled his effort to make sure that he did everything
    > possible to ensure that celestial would get them to Howland. If he
    > hadn't been confident of this they would not have left with an unproven
    > radio direction finder.
    >
    > I don't know how many instrument rated pilots we have on this forum. I
    > am an airline transport pilot and I have also been an instrument flight
    > instructor since 1972 so I have some knowledge of how radio direction
    > finders work since they were common navigation equipment �in airplanes
    > used for flight in the clouds until the recent development of GPS. (I
    > also have a radio amateur operators license, call sign KA9UHH.)
    >
    > When flying on instruments you are inside the clouds and can't see any
    > landmarks, obstructions or airports. In order to navigate without visual
    > references you rely on different systems of radio navigation equipment
    > which for many years included radio direction finders very similar to
    > the one installed in NR16020. This equipment uses long wave radio
    > signals in the band of 190 to 535 kilocycles (now kilohertz) just below
    > the A.M. broadcast band and including 500 kcs the international calling
    > and distress frequency. This was the frequency that Itasca was
    > broadcasting on. AE's radio direction finder should have been able to
    > get a null and and so determine the bearing to fly to get to Itasca.
    >
    > Getting a null involves turning the loop antenna until it is lined up
    > with the direction of the incoming signal which is shown by the received
    > signal getting �weaker and weaker until it disappears, this is the
    > "null." If you turn the antenna past the null the signal starts to get
    > louder very rapidly. The width of this null is very narrow so that the
    > bearing can be determined very accurately.
    >
    > This type of equipment is good for a very long distance mainly
    > determined by the power of the transmitting station. For enroute
    > navigation, airways, like "highways in the sky" were created with radio
    > transmitters placed on the ground at each end of each leg of the airway.
    > The signals have to be strong enough so that you can receive them at the
    > halfway point of each airway leg. You track outbound from one station
    > until halfway to the next station then start following the signal to the
    > second station. As an example, a route I flew many times was �"A17" from
    > Bimini, Bahamas to Puerto Rico. You take off from Miami or Ft.
    > Lauderdale and tune in the radio station on Bimini which transmits on
    > 396 kcs with a Morse code �identification of "ZBB." You use the radio
    > direction finder to head for Bimini which is 55 NM from Ft. Lauderdale.
    > After passing over Bimini you turn to a heading of 121� magnetic and
    > track outbound until halfway to the next radio station located on the
    > island of Grand Turk at the very southeast end of the Bahamas chain.
    > Grand Turk transmits on a freq. of �232 kcs with the ident of "GT."
    > After passing GT the next station is located on the north shore of
    > Puerto Rico about 60 miles west of San Juan transmitting on the
    > frequency of 391 kcs, ident "DDP." Now here is the important part, the
    > leg from ZBB to GT is 516 NM (593 miles). This means that you can
    > receive the signal 258 NM at least from each station. It is reasonable
    > to believe that had AE's radio direction finder been working she would
    > have been able to hear Itasca at a similar distance. This is born out by
    > the fact that Itasca heard AE's much less powerful transmitter several
    > hundred NM out.
    >
    > Since the leg from Lae to Howland is 2222 NM and the common estimate of
    > DR accuracy is 10% of the distance flown then one could expect to fly
    > the distance from Lae to Howland solely by dead reckoning and still be
    > confident of coming within in 222 NM of Itasca and so be close enough to
    > pick up the radio signal and track inbound to Howland. So if AE was
    > willing to rely only on radio she didn't need Fred at all. In fact, they
    > saw Nauru island about half way so the dead reckoning leg would have
    > only been about 1,000 NM so the DR error should not have exceeded 100
    > nm. But obviously they wouldn't just rely on radio.
    >
    > It is hard for young people today who have grown up with cell phones,
    > the internet, TV, satellite dishes and IPODs to have any gut feeling for
    > the unreliability of radio equipment in the 1930s. Modern equipment and
    > systems are so reliable people don't even think about it anymore. But in
    > the '30s comparing the reliability and trust in complicated pieces of
    > electronic equipment with resistors, capacitors, and tubes that burned
    > out without warning in your own equipment and in the transmitting
    > equipment that was not under your control with the proven reliability of
    > a simple sextant, a book of tables and a clock (or two clocks for
    > redundancy) and celestial won hands down. That was why AE hauled Fred
    > all the way around the world.
    >
    > Back to the use of radio direction finders. When flying on instruments
    > you eventually have to descend to land at an airport that you can't see
    > while you are in the clouds that might be in a valley surrounded by
    > mountains. You fly to the approach radio station on a specified course
    > and altitude and then after you pass over the transmitter's antenna you
    > know it is safe to descend �down to the minimum decent altitude that has
    > been established by the FAA for the approach to that airport which takes
    > into account the height of surrounding obstacles and the altitude of the
    > airport and the distance from the transmitter to the runway. When you
    > pass over the antenna and start your final decent you start a stop
    > watch. Your approach chart tells how many minutes and seconds it will
    > take you to fly from the station to the runway at various ground speeds.
    > After you descend to the minimum descent altitude you maintain it until
    > you see the runway of until the time runs out by which you know you have
    > passed over the runway without seeing it so you must climb and go to
    > your alternate.
    >
    > The reason I went through this long winded explanation is so everyone
    > will understand that the radio direction finder works right over the
    > transmitting antenna, you can't get closer than that. AE dismissing the
    > failure of her radio direction finder because she thought she was too
    > close to the transmitter shows either she didn't understand its
    > operation or she was satisfied that celestial alone was sufficient to
    > get them to Howland. I think the latter explanation makes the most sense
    > since they could have (and probably did) check the radio direction
    > finder operation as they flew farther away from Lae and continued on
    > even though it was apparent that it wasn't working. Again, this would
    > have made Fred work real hard on his celestial since he knew, actually
    > KNEW, that he couldn't depend on the radio.
    >
    > Based on all this I believe Fred knew he had to do an exemplary job of
    > celestial navigation and if the radio did per chance work when they got
    > near Howland then "no harm, no foul." He had confidence in celestial and
    > knew it had sufficient accuracy to locate Howland or he wouldn't have
    > gotten into the plane.
    >
    > gl
    
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