Moggy’s Tunaboat Helicopter Manual "GPS 4-5"

Posted on April 13, 2010

Moggy’s Tunaboat Helicopter Manual

Section 4.    GPS Systems and Offshore Navigation Issues

4-5   Hey, it sure is getting dark!

       Why, you may wonder, a whole chapter devoted to ‘sunset’?
Because it catches people out. The closer you get to the equator, the faster the sun sets. You may have had a nice blue sky all day, with only a fringe of solid, but low cloud on the western horizon. Somehow this lulls you into a false sense of security. That fringe of ‘solid but low cloud’ is really going to bite you.
It’s uncanny how fast the sun sinks. Especially when you’re struggling into a headwind, a bit tight on fuel, and flying a Bell 47! Combine that rapidly sinking sun with that low cloud on the western front, and you’re in for a short twilight. Next thing, it’s dark! With no cockpit lights, no attitude indicator, and no visual references, you will have to land in the sea. It’s like somebody hit the light switch…

      Let me tell you another story against myself -yes, I wasn’t all that smart – to illustrate the point.
We had been searching all day for fish. It had been a big ‘nada’. On the third flight of the day, at about 35 miles due East of the ship, we spotted some large foamers a few miles further East. The wind was westerly, and a good 15 knots. I suspect to this day that the observer, who was also the ship’s navigator, used to study the stopwatch and the GPS, and used to do his own ‘flight planning’.   I further suspect that he simply took the ‘time to go’ (back to the ship) straight off the Tigershark, (at the outbound/tailwind promoted ground speed) and
completely failed to allow for the return headwind and consequently greatly reduced ground speed. Some GPS units will simply not give you a ‘time to go’ back to the ship if you are heading away. Others however do. In other words, the GPS will simply take your present with-the-wind high ground speed, and use that erroneous figure to give you an estimate back to the ship. A hopelessly optimistic figure!

      Now I wasn’t that green, and I was doing the mental arithmetic for FUEL remaining, and I usually subtract 150 per cent of the expected headwind from my airspeed. So there’s an extra safety factor. But like I said, I suspect muggins beside me was ‘playing pilot’. Without allowing for the radically different ground speeds. A little knowledge is a dangerous thing. At any rate, when I wanted to turn back, he became downright unpleasant. He roared and bawled and yelled and screamed. He was pissed – he wanted to stay over the foamers.
I allowed myself to be intimidated for a precious ten minutes or so. I was new, anxious to please, a bit upset, and now distracted by him! (I have long since learned the trick: you announce ‘five minutes!’ After that, you turn and fly home! You don’t even COMMENT on any histrionics. You simply turn a deaf ear. The noise soon sputters to an indignant stop) And so it was that I re-ran the mental arithmetic over and over again. I left out one calculation because it simply never occurred to me: DAY LIGHT remaining…

       I can say that my fuel calculations were spot on.  We never had a problem there.
But… the funny thing is that I remember turning around, knowing we had a fifty minute ride back. At that stage, I remember the sun was so pleasantly high in the sky, I still didn’t think about DAY LIGHT remaining.

      Then that golden orb started to sink. And sink. And sink. It positively plummeted…
The low,solid cloud bank that had appeared so benign and harmless, suddenly started to take on more ominous characteristics.
                        Oh, sh….t !!
Soon it was obvious that we were heading into trouble. My observer, who had been giving me abuse for the first five minutes of the return journey, now became rather quiet…
The sun hit the clouds, slithered down behind them so fast you could see it disappear, like a monkey down a greasy pole, and seconds later all the lights started to go out! It’s weird. One moment it’s broad daylight, the sky is sunny, and you’re able to see everything on the instrument panel as clear as anything. A few minutes later, you are straining and peering at your instruments, running all sorts of calculations, and wishing you were home!

      The little Bell 47 was doing its best, as I slowly wound on more and more throttle. I was redlining it, poor thing, and still we had fifteen minutes to go. It got darker and darker. The sea was now featureless.
Now the ship’s lights were on, bright lights in a dark void. The ominous clouds, with the westerly wind, had reached the ship, and soon we were underneath them, feeling the first drops of rain, splattering accusingly on the windscreen..
                      Errrrrrr…..which ship?
There were at least two, five miles or so apart, and the GPS seemed to be indicating somewhere between the two. Bright lights, black background. I could still make out references by which to fly, but these were fading fast. I asked my observer, more in hope than in trust,if he knew which was our ship. I wanted to save every minute I could! He swung up his binoculars, studied the lights for a few seconds, and then, rather to my surprise, positively indicated one of the lights.
              "Are you SURE?"
I almost snarled it. He was not my flavor of the month.
I swung the helicopter directly for the lights indicated, hoping to save a few minutes.
We had not gone far, when the captain’s calm voice came over the headset.
                "Moggy! Wake up! Stupid Paddy! You go to wrong ship!"
He was watching us on radar!
My observer physically flinched, that slight ducking and bowing of the head, shoulders raised, that indicates guilt, and I positively GLARED at him across the dark cockpit. If looks could kill he would have been thrashing around, foaming at the mouth, dying a horrible death!
The fact of course was that it was really all my own fault…

       We turned onto the new course, courtesy of the radar heading provided by our vigilant ship’s Captain, and I initiated a shallow descent. I had been a night flying instructor, and I knew the risks (and the phrases from the many accident reports) of ‘rolling around a single light on the horizon’ and ‘descending inadvertently into the sea whilst pre-occupied with distant lights’.  I could just about keep references. As we got closer, the ship grew in size, and now it was easier.
We landed safely, out of the dark sky, with rain falling, but another few minutes would have meant a precautionary landing in the sea. I had learned once again, and not covered myself with glory!

       You’ll note the Taiwanese captain did rather well -again! This man would never have gone to bed with his helicopter still flying. No matter how tired he was. This man was sharp. We return to this later…  

Francis Meyrick

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