The island of Tarawa is 2000 nautical miles southwest of Honolulu. Like many of the Pacific islands, it rises out of the water only a few feet. The palm trees along the beach can double that height. No 14,000 foot high mountains like Mauna Loa or Mauna Kea on the Big Island of Hawaii serve as beacons to guide you for the last hundred miles. It's just plain flat. And the island is only a few miles in diameter, so if you don't fly directly over it, clouds or haze will block it from view. You could pass right by it and never know you missed it.|
It's a pleasant place to stop for fuel and rest; all you have to do is find it. That's why a radio-navigation beacon was installed there.
The radio beacon at Tarawa isn't turned on unless a flight is scheduled to land. There isn't enough traffic to justify having the beacon run day and night. All you need to do to have the beacon turned on is fill out a request before you leave Oakland. Figure out when you plan to arrive, adjust backward a few hours so they don't wait to turn on the beacon just as you go whizzing by and hand in the request. By the time you have flown the 15 hours it takes to go from Oakland to Honolulu, fueled and rested, the confirmation message will be waiting for you at the Honolulu Flight Service Station. You can pick up a copy when you file your Flight Plan for the Tarawa leg. Piece of cake.
The flight to Honolulu was uneventful. That's the best kind of flight you can have. The first leg is like a shake-down cruise. If the squawk list is looking pretty modest when you arrive in Hawaii, chances are the rest of the trip to Australia will be pretty easy. Such was the case on this trip. It wasn't until the next morning that it became apparent that a Cessna 402 might be joining me in my 2-man life raft.
I planned to depart Honolulu at about 9 PM in the evening. I'd fly through the night and arrive at Tarawa in the morning. The LORAN A navigation system would be useful over most of the trip during the night and when the signals faded out at sunrise, the Tarawa beacon would guide me the last few hundred miles, neatly pasting together a navigation plan for a route that lacked in nav aids.
This plan had several advantages over flying during the day. The daytime LORAN coverage wouldn't come close to matching the coverage at night. During the day, only the first third of the route would be adequately covered, leaving the next two-thirds to be flown by pilotage. Knowing where you are seems an essential ingredient of safe flying and I had already seen how well pilotage works on long trips. In addition, there were no lights on the runway, so arriving late in the afternoon held the possibility of groping around in the dark, trying to find something black to land on, other than the ocean, if any delays developed.
With a copy of the beacon confirmation message in hand, I departed from Honolulu, right on time.
As expected, the LORAN signals were strong enough to give good fixes, hour after hour. When the readings were plotted, the dots on the map marched right on down the line I had drawn the day before. Within minutes of the time I had estimated that I would arive at a fix, the pencil marks showed I was there. Position reports went out with precision; having a solid high-frequency radio link with the ARINC operator in Honolulu made that easy. Heading changes weren't to correct for bad wind information, they were to correct for drift in the directional gyro, to which the autopilot was slaved.
It seemed prudent, at about 3 o'clock in the morning, to see if the beacon at Tarawa had actually been turned on. I dialed the beacon frequency of 375 KHz into the ADF. A good, strong signal straight ahead would have caused the pointer to rotate to a straight up position. No such luck. The pointer drifted aimlessly. Was the beacon on, but too weak to move the needle? I turned up the volume control on the receiver to listen for the Morse code identifier transmitted by the beacon. Not a peep. How far out should I expect to hear the beacon? Maybe 500 miles was pushing it.
I resorted to a little trick to coax more information out of the ADF receiver. I moved the digital tuning control up by the smallest increment, one kilo-hertz. There was a barely noticable change in the noise coming from the receiver. It got just a little bit quieter than when the frequency was adjusted to the correct value. Encouraged, I dialed down to one kilo-hertz below the beacon frequency, stopping for a moment on the correct frequency. Yes, it was true. There was a noticeable increase in the noise as the receiver was tuned to the beacon and a decrease as it was tuned to either side. There wasn't enough of a signal to pick out the Morse code identification, but I was confident that the beacon was going to be available when I got closer.
A two thousand mile flight takes a long time at the speed of a twin-engine plane. There is plenty of time to think ahead and plan for alternatives. Since I had good position information and knowledge of how fast my fuel was being used, it was easy to calculate that I would have plenty of reserve at the destination. I could also calculate the point at which a return to Honolulu was no longer an option. The point-of-no return was now behind me. It was Tarawa or Bust.
An hour later, and 150 miles closer to the island, I tried again to identify the beacon. This time the noise increased considerably when the receiver was tuned to the correct frequency and the pointer was now pointing back and forth in little gentle arcs about the straight up position. There was, in fact, a signal on the frequency where there was supposed to be one, it was getting closer and it was close to straight ahead. Three good signs, all saying the island of Tarawa would appear just ahead in another few hours. But it still wasn't strong enough to hear the Morse code indentifier.
The sky started to lighten behind me as the sun crept up to the horizon. In another hour it would be up and my trusty LORAN signals would be gone.
That hour went by before I turned up the ADF receiver volume again to check for the Tarawa beacon. The pointer was now swinging casually around the straight up position indicating a strong, reliable signal coming from a source nearly straight ahead.. And sure enough, there was a strong tone as each letter of the ID issued from the receiver. The letters spelled out T.. K.. K.. Wait just a minute. I was looking for T.. W... What could be wrong?
A quick glance at the South Pacific beacon chart gave the answer. The beacon I was listening to was not the Tarawa beacon after all. It was the beacon on the island of Truk. Not quite straight ahead, but beyond Tarawa by another 1200 nautical miles. I had fooled myself all night. The beacon on Tarawa had never been turned on. I was heading for Truk with just enough fuel to reach Tarawa.
A check of the LORAN confirmed that the signals which had been predicted to fade out at sunrise had done exactly what they were supposed to do. They were gone. The LORAN would be useless until darkness returned.
So there I was, a few hundred miles from my destination with just an estimate of where it was and no good plan for getting there. My entire plan had gone from bullet-proof to bogus in just minutes.
So why not keep going straight? I was headed directly for Tarawa; the LORAN plots all night had shown that I was on track. I knew how fast I was going and exactly when I should arrive. Thoughts of Amelia Earhart came to mind. That was exactly what she had done. Point toward where the destination should be and wait...
I turned immediately toward Majuro, in the Mashall Islands. The navigation beacon there runs 24 hours a day. It was strong and always available. A quick calculation showed I had enough fuel to get there with no reserve. If the winds were favorable, I would make it. If not, I had brought my life raft along for days just like this.
The ARINC operator in Honolulu responded immediately when I informed him of my situation. They took my estimated time of arrival at my new destination and told me they would try to get in touch with someone on Tarawa who could turn on the beacon.
A few minutes later, ARINC called me back on the HF radio to tell me the Tarawa beacon had been turned on. I checked the ADF receiver again; he was right. The beacon ID of the now much stronger Tarawa beacon had completely covered the weaker signal from Truk. I changed my heading back to Tarawa and reported that to ARINC.
Within the hour the island of Tarawa came into view and a few minutes later my Cessna 402 was rolling to a stop after a smooth landing on the white surface of the crushed coral runway.
Life on the the island proceeded at the pace it would have whether I had arrived or not. The airport was deserted. No people, no buildings, no nothing. Just a runway on a coral atoll, 2000 miles from Honolulu. As I rolled to a stop, I called Honolulu on the HF and reported my safe arrival and thanked them for a nice diving catch in the end zone. I had Bonriki International Airport all to myself.
The British Petroleum attendant eventually appeared and helped me refuel. His paperwork clearly set forth how much fuel I needed and the proper grade. I was there at the appointed hour and his job was soon finished. All in a day's work.
He never knew how grateful I felt to be standing there in the warm sun, feeling the gentle tropic breeze, watching the palm trees sway over the beach.
Amelia Earhart would have loved it, too.
If you check a current chart, you will find that the radio beacon frequencies for Truk and Tarawa are no longer the same. Putting two signals on the same frequency which are within range of each other can lead to navigational difficulties, as I proved.
The LORAN A navigation system no longer exists. It has been superceded by LORAN C, another ground based system. The Transit satellite system patched some of the limitations of the ground based LORAN chains, but even that has been decommissioned. The satellites of the Global Positioning System now give a fix within one hundred meters once per second.