Sunday, December 8, 2013

A Hole In The Cloud

Fans of aerial combat will remember how Allied bombers over Germany looked for holes in the clouds to descend through and then looked for their targets. When flying in the early mornings,  I had to use the same technique to reach some destinations. This manoeuvre is not without its risks, so I avoid it as much as I can.
In the early nineties the GPS for aerial navigation was still an expensive equipment, costing more than RM4,000 each. We flew using only maps and the magnetic compass. As the latter swings erratically and takes a long time to stabilise whenever an aircraft changes direction, another instrument called the Directional Gyro Indicator (DGI) is used. This is a more reliable instrument but the pilot has to regularly feed in the headings that he reads from the magnetic compass into the DGI which always "drifts" as time passes.
I was flying from Sempang (the callsign for the RMAF base on Jalan Sungei Besi in Kuala Lumpur) to Taman Negara in Pahang one cool morning. Taman Negara happens to be my favourite weekend destination whenever I fly. It is only an hour's flight away and yet is a thick tropical jungle protected by law and had existed for 130 million years untouched by glaciers. It had clean rivers, cool waters and many rapids.
The sky was clear when we left. Our flight plan was filed for Batu Caves, Bentong, Jerantut and then Sungai Tiang which is the laterite airstrip located about five kilometres downstream from Kuala Tahan, our eventual destination. It is the site of most tourist amenities in the area. After Batu Caves,  we passed Genting Highlands on our left and was overhead Bentong airfield which in reality is a fairway on the Bentong golf course. Overflying Bentong at our cruising altitude of 3,000 feet,  we tracked direct for Jerantut which took us to the right of and below the peak of the majestic Gunung Benum. However we found that the cloud cover below us was thick and had blanketed the entire terrain ahead of us leaving no landmark for us to refer to. Jerantut was up ahead somewhere and we had to find it somehow since our subsequent leg to Sungai Tiang was by following the Pahang River northwards beginning from Jerantut.
We had an instrument on board called the Automatic Direction Finder (ADF) which can be used to track a radio signal from any radio station. This instrument is usually unreliable as it will point to any electrical source nearby such as a cloud with an electrical charge or some unknown radio transmission. Knowing that Jerantut has a radio broadcasing station, I tuned the ADF to the station's frequency but this time there was nothing heard and the needle pointer was rotating all over the gauge.
There was no other choice but to find a hole in the cloud below us and go down it to see what landmark lay below that we could recognise. Comparing our elapsed flight time and airspeed with our navigation log, we should have just passed Jerantut. Luck was with us and a reasonably sized hole in the white substance below us was nearby. We had to go through it quickly or it may close back leaving us stranded in the sky. The C172 is not a fighter plane that can zip down a hole just like that. I had no dive brakes. If I were to simply dive the plane through the hole, the gravity would accelerate it to a speed beyond its limit and rip its wings off. After checking with Air Traffic Control that no other traffic was nearby, I put the plane into a shallow spiral dive with twenty degrees flaps and kept the airspeed near the limit. Peeping through the hole I could see flat terrain below, so there was no danger of hitting a  hill or something.
After what felt like hours, we finally were below the cloud which was just a thousand feet above the ground. Visibility was good. I looked around and saw a river not far off, headed towards it and from its size knew that it was the right river although Jerantut was nowhere to be seen. We headed north along it confirming the layout with that on our map. Further upriver there were familiar-looking boats that added to my confidence that we were at the right river. Taking the correct forks as we flew on, we finally saw the Sungai Tiang airstrip and landed.

I locked the plane up and we walked to the jetty to wave down a boat, as I used to do, to take us on a one and a half hour ride to Kuala Tahan. The cool breeze that blew as the open boat trundled through the rapids was very welcome indeed (the normal passenger boats usually have a canopy above to ward off the sun).

We lunched at the usual cafe, walked around and then took another boat back to the airfield.  This time the warming earth had pushed the morning's cloud layer up a couple of thousand feet to form fast growing cumulus hills that will not only affect our visibility but also make the flight home a bumpy one.

1 comment:

  1. Hello, I was wondering whether you could comment on the condition of the airstrip and runway as I am interested in flying to Sungai Tiang.
    Could you send me an e-mail to zhiming (at)
    Thank you.