Gavin Grimmer
I believe he was just about to ask permission for any assistance needed to get back out to the coast in case he strayed into their airspace, but of course he was distracted from continuing this request.
What height they were at when they struck the 'downdraught' is anyone's guess as he didn't state their altitude at that point, but we would have to presume they were somewhere around 8500 ft. They could have been higher by then, or lower. Just because he said further back that they were struggling for 8500 doesn't mean to say that they didn't gain some more further on from that, but as we were struggling in the time-frame allowed to place them in a position where the updraught would have run out, I would doubt that they had gained any. Just because they were descending at about a thousand a minute at that stage, also doesn't mean that they continued at that rate. Between there and the point where Mike reported 7500, they could have had some short periods of lift?
We cannot presume anything!... but hopefully the calculations may provide some conclusions....
The cloud as shown in the above Google Earth depiction, I placed as a means of trying to determine which lights of which towns Mike saw on the coast. The word “towns” suggest they weren't huge 'towns' such as Newcastle, so this only leaves Nelson Bay and Forster and maybe Taree. There are a few smaller towns, but if you were in the same situation as Mike, I'm sure you would head for the biggest one. With the benefit of the further radar positions given, we can get a better direction of where they appeared to be traveling and which town... Forster. The picture I have in my mind in researching this is that Nelson Bay was obscured to Mike by cloud anyway.
09:34:43 “ ….just to compound things, we thought we had a cockpit fire but we seemed to have resolved that little problem..... I wonder if this 'cockpit fire' was just the smell of smoke from one of the many burn offs reported all over that area that night? Smoke does not normally get that high, but I wonder if with the strong winds and updraughts, it could have got that high? … just a thought!... or maybe a smoker on board lit up to calm his nerves?
This track to Forster of 95° would give a ground speed of 209 knots (160 knots plus tailwind component) using a direct westerly wind of 50 knots as reported by VH-CNW, and also by VH-ESV when he was conducting an aerial search later on the eastern side of the Barrington Tops – not long after the event... “Very strong from the west. Turbulence moderate or less”.
AIRSPEED CONCLUSIONS
At this point, we should discuss his airspeed as there has been many discussions on this in various papers written, and on various blog sites over the years.
All the calculations up to this point show that to travel the distances needed to be at the various positions and known radar determined positions, an airspeed of at least the flight-planned TAS of 160 knots was needed. In fact, a reduction in speed would deem MDX to be in these positions at those times impossible! Why would he push the limits of the airframe and risk pulling the wings off or do other damage to the airframe you might ask?
I think the answer is very simple... the turbulence was only as others had described
it - as light to moderate, and Mike's personal tolerance to turbulence was very low.
Other pilots had spoken of how Mike went to extreme lengths to avoid it.
The less
time spent in it, the rougher it seems when you do get in it.
The other factor was as this C210 performance chart shows. Note what I have high-lighted.
I was taught that it was safe to fly an aeroplane in turbulence up the top of the green range (Vno)... (or was I taught wrong?), or to put it another way... quote from another C210 document: “May not be exceeded unless in smooth air conditions”. The next arc on the ASI is yellow, and this is the range that you could go into - but only in smooth air, and of course the next was the red (just a red line at right angles) - never exceed!
I think many are getting confused with Va (Maximum Maneuvering Speed). This is only a speed that should never be exceeded when full and abrupt harsh movements of the control surfaces are made as this puts undue stress on the airframe. As per the 165 KIAS shown here for Vno, this calculates out at 8000 ft of around 190 KTAS, so it beats me what all the fuss is about?
Mike was well within the limits flying this aircraft in moderate turbulence at 160 KTAS, but from my point of view, it would have been advisable to slow it down to get a smoother ride. The maximum Va of 125 KIAS converts at 8000 ft to 145 KTAS and for those that don´t know, the range of 125 -101 KIAS (as shown on image) is 125 = fully loaded verses 101 = lightly loaded.
AUTOPILOT
Another factor rather pertinent to this case is the fact that VH-MDX was equipped with a Cessna ARC Navomatic 300a Autopilot which was basically what was known as a “Wing Leveler”. This device had the capability of holding a heading by turning the plane back onto the heading if it drifted off by use of the ailerons – but only if the Directional Gyro/Vertical Compass Card was working. As we know, this was not. The device was designed that if this gyro failed, it then reverted to using the “turn and bank instrument” to retain the wing leveling capabilities – but it no longer had a “heading hold” function. Keeping the wings level would have been a huge advantage to lightening the workload on Mike, and I think this was why he appeared to have remained so calm throughout much of his ordeal... other pilots listening in commented on this.
MDX pg 18
