Air Safety

Most of my agency work was in country NSW, but this time I had an important meeting in Melbourne. I had intended to go down by airline, but when one of my clients rang from Wagga to say he wanted to see me, I decided to kill two birds with the one stone and do the round trip in the 182. So I made arrangements to fly to Wagga the day before I was due in Melbourne, stay overnight, and depart for Moorabbin early enough to get me to the meeting in the city proper at 10am.

I had flown myself to Melbourne only once before, and that some years previously when I had puddle-jumped a club Chipmunk down via Benalla and the Kilmore Gap. But now, as a rated instrument pilot (well almost!), such crudities were not to be tolerated; in a manner befitting my status, I would flight plan from Wagga via the navaids at Albury and Eildon Weir, thence direct to the Moorabbin NBD.

In the event I was late getting started; the night porter at the Wagga motel forgot to call me and I slept later than intended. By the time the taxi had dropped me out at Forest Hill and I had preflighted the 182 and got to Flight Service, it was a quarter past four.

The area forecast was for a light southerly with clear skies inland, but with a broken layer of strata-cu over the ranges at 3,000 feet. The TAFOR for Moorabbin was for two oktas of cloud at 4,000 feet, wind 190 degrees at eight knots, and a QNH of 1,014 millibars. I flight planned at 6,000 feet until approaching the 4,000 foot control area step just north of Healesville, thence OCI A below the steps to Moorabbin.

But when I passed him the plan, the Flight Service Officer pointed out that if I was still Night VMC at this stage, I would need an airways clearance to maintain the required 1,000 feet above terrain. As the Lowest Safe Altitude for Eildon Weir-Moorabbin was 4,370 feet, this meant entering controlled airspace at 6,000 feet. I altered my flight plan accordingly and away I went.

Setting course at 1854 hours UTC, I climbed to cruising altitude. First Holbrook, then Albury – an unmistakable galaxy of light- came up on schedule and I made the change of heading for Eildon Weir, initially tracking outbound on the Albury VOR. At this height, with a head wind component of a little under 15 knots I was cruising at 124 knots TAS.

So far the forecast was spot on. Around Mansfield (also easily recognisable on this dark night), isolated patches of strata-cu began to appear below, the cloud gradually increasing as I continued further south.

When the VOR needle indicated ‘station passage’ right on ETA at Eildon Weir, I again made the necessary heading change (only five degrees this time) and tracked outbound; at this early hour I didn’t expect to receive the Moorabbin NBD until much closer in. Away to the east, the planet Venus blazed like a fireball and the sky was streaked with the pale light of the coming day.

Calling Melbourne Flight Service, I passed my position and ETA for Moorabbin, requesting an airways clearance at 6,000 feet. In a few moments the operator came back with: “Call Melbourne Control!” This I promptly did and repeated my request. Melbourne Control then cleared me at 6,000, adding, “Call Melbourne Approach on 124. 7 abeam Healesville. ”

That’s really where the rot set in- I had to confess that I didn’t have 124. 7. There was a pause during which I was asked to standby again, then came the further instruction: “Call Melbourne Departures on 118. 9 abeam Healesville. ” Sheepishly, I had to admit I didn’t have the Melbourne Departures frequency either. This must have set the cat among the pigeons because there was a much longer pause before the operator called me back again. Finally he informed me apologetically that I couldn’t be accepted within the MelbourneControl Area without the Approach or Departures frequency, and that I was to remain outside controlled airspace.

Re-establishing contact with Flight Service as instructed, I was asked to “advise intentions”. By this time it was getting light enough to see the ground through occasional gaps in the underlying cloud, though not enough to make out any detail. Official first light could not be many minutes away, so I took a punt on it: “Will proceed to Moorabbin OCTA Will hold at altitude 6,000 OCTA if necessary until first light,” I replied.

This apparently got the operator off the hook, for he came back with a cheerful: “Roger . . . for your information first light at Melbourne is at 2019 hours. Advise when commencing descent. ” That was 0619 EST, only 11 minutes from now and around my ETA at the 4,000 foot control area step. It was doubtful if I would have to hold at all- everything was working out, despite the hiccup over the frequencies! Just as well I was late starting, I told myself! Though the deck of cloud below me had now become eight oktas, I wasn’t concerned because I could see it ended abruptly some distance ahead.

Checking my Visual Enroute chart as I worked out a time to commence descent, I saw that at the azimuth angle at which I was approaching the CTA steps to the north-east of Melbourne, my descent path would miss the 3,000 step altogether and that only about 15 nautical miles past the 4,000 foot step, I would have to be down to 2,000 feet. I would need to be disciplined about maintaining the descent rate all the way down from 6,000, I told myself- a thing easy to be careless about with no obvious topographical reason for doing so.

Calculating an accurate ETA for the 4,000 foot step and taking off four minutes to allow for 2,000 feet of descent at 500 feet a minute gave me a time of 2013 for leaving 6,000 – six minutes before Melbourne’s official first light.

In the gloom beyond the edge of the cloud dark in the distance now I could just make out what appeared to be-the green pastures of the Yarra valley, with a mountain further away to the left on which there were television masts – undoubtedly Mt Dandenong. Conditions were obviously clear in the Melbourne area!

At this altitude now it was light enough for me to see what I was doing; then as I looked at the chart, I realised first light here would be about three minutes earlier than the time Flight Service hadgiven. So as soon as the clock indicated 2013 hours I did one orbit, then pushed the nose down, eased the power back to 22 inches and trimmed the aircraft into a 500 foot a minute descent. Four minutes later I found myself skimming the top of the strata and levelled out at just under 4,000 feet.

With the edge of the cloud deck still apparently a good way ahead (being so close to it now I couldn’t see exactly how much further), I was now becoming increasingly concerned it would prevent me from getting down to 2,000 feet by the time I reached that boundary’s position. After some hesitation I decided I would have to crib a bit. There could surely be no harm in doing so – from the view I had got while on the way down from 6,000, the valley floor was a very safe distance below the base of the cloud.

So once again I trimmed the aircraft into a 500fpm descent, pulled on full carburettor heat, and plunged smoothly into the bank of strato-cu.

With the altimeter unwinding steadily in the grey, wet opacity, I wasjust congratulating myself on what a clever fellow I was when suddenly there were several unnerving thumps on the undercarriage legs, the aircraft lurching at the same moment, and for a fleeting instant something scraped against the underside of the fuselage. My immediate thought was that I had flown into a flock of migrating ducks . . . do ducks fly in cloud?

Not more than 30 seconds later I broke out of cloud to find myself looking down on green fields 2,000 feet below me. Then the port main wheel spat caught my eye; the front of the streamlined fibreglass fairing had a gaping hole in it – and wedged between the fairing and the spring steel undercarriage leg was a piece of gum tree about as thick as your little finger, the few leaves that remained on it fluttering wildly in the slipstream! A cold chill of fear shot through me and my arms and legs suddenly felt as though they had turned to water. Desperately I tried to think what I should do. Then, as I checked the descent at 2,000 feet, I caught sight of a neat grassed airstrip (complete with hangars and lines of parked light aeroplanes) almost directly below. I identified it from the chart as Lilydale.

Forcing myself to sound calm, I called Flight Service. “Diverting into Lilydale”, I informed the operator in my most professional aviation voice. “Will call again on departure in approximately 30 minutes. ” Fervently I hoped it would be possible. Somehow I also remembered to extend my SARTIME.

I flew a circuit, landed, and taxied in. There was no one about as I shut down the engine – it was still too early in the morning. As I clambered out to inspect the port spat more closely, I was aghast to find the nose spat almost completely gone – only torn fragments of fibreglass remained around the attachment bolts. Moreover, tiny pieces of green wood were jammed in amongst them. The starboard spat, though bruised on its leading edge, was reasonably intact. To my immense relief, the propeller showed no sign of damage. I crouched down to examine the underside of the fuselage; the light film of dirty oil running back from the engine cowling exhibited telltale marks of scratching, apparently by tree foliage.

Gazing back to the north at the range of tree clad mountains which form the edge of the Great Dividing Range at this point, I could see the cloudbank lying close to their tops. But further to the north-east a higher, steep sided peak reared right into the cloud itself, its top lost to view.

Hardly daring to think about it, I took my tool kit from the rear compartment, unbolted what remained of the wheel spats, stowed them out of sight, then removed all signs of foliage and bracken from the aircraft. By this time of course, the sun was up, and after a careful walk around, I climbed aboard again and resumed my flight to Moorabbin.

I got to my meeting all right – but I can’t say I remember much of what was said. My mind was otherwise occupied!

Putting it all together later after studying my charts, talking to other pilots at Moorabbin (without letting on!), and looking at the terrain again in clear weather on my way home the next day, I finally worked out what happened.

The direct track from the Eildon Weir VOR to Moorabbin airport passes for its first half over mountains and valleys of the Great Dividing Range, then abruptly leaves the ranges and continues over the relatively low lying terrain of the Yarra valley and the Port Phillip coastal plain. A little less than half way, and just inside the 4,000 foot control area step, the route passes directly over the summit of Mt St Leonard, a spot height of 3,373 feet on the WAC char t, the highest terrain on the route. From this point the terrain drops steeply away to the floor of the Yarra valley.

That really meant that an aircraft flying the precise route OCTA had a theoretical vertical airspace margin of only 127 feet as it crossed the top of Mt St Leonard if its flight was to remain legal with respect to the control area step and the mandatory 500 foot terrain clearance. In practice however, there was no margin at all because the mountain is covered in tall trees (not allowed for in spot heights!) and there is a prominent fire lookout tower on its summit.

After squeezing between the top of Mt St Leonard and the base of the control area step, the aircraft was then required to have descended to 2,000 feet only 12 nautical miles further on, or within five minutes at the speed of a Cessna 182.

All this juxtaposition was required at the very time the pilot had to transition from the Visual Enroute chart to the Visual Terminal chart, thereby distracting him from the terrain information on the WAC chart. Moreover, though the VTC contained terrain information (unlike the VEC which had none), the crucial Mt St Leonard spot height just missed being included on it.

Add to this the meteorological phenomenon that, in southerly stream weather, a deck of cloud often ‘sits’ on the top of Mt St Leonard – and you have a deadly trap set for unwary pilots.

In my own case, having decided to drop through the layer of strato-cu on the basis of being able to see the lower terrain beyond the cloud bank and because of my perceived urgency to continue descending, I had run the undercarriage through the very tops of the trees on Mt St Leonard, never dreaming the mountain was so perilously close to the base of the control area step!

Why, I still wonder, do control area steps have to be so ‘tight fitting’ above terrain? Instead of simply relating the steps to radial distance from primary airports, couldn’t some cognizance be given to the height of terrain in critical areas? And couldn’t an extra 1,000 feet be added in those areas? It is difficult to accept that ATC requires the use of controlled airspace that impinges so closely on underlying terrain.

Just as importantly, couldn’t some terrain information be provided on VECs when safety is at stake? Even a placard on critical spots, warning pilots to crosscheck with their other charts, would be better than nothing.

The margin by which I avoided a violent end on the cloud enshrouded mountain early that morning is frightening even to contemplate. Clearly, if my 182 had been only centimetres lower when the undercarriage struck the tree tops, then I would have joined all those other unfortunates who have met their demise in what the Aviation Safety Digest used to call “conditions in which visual flight could not be maintained. ”

It was a brush with death I will never forget – yet all it cost me was a set of new wheel spats. I don’t think anyone else ever suspected what happened – at least no one ever said anything. Yet I can’t help wishing I could have told the story with effect at the time. Some time later a party of German private pilots visiting Australia on an aero club tour did almost exactly the same thing.

Tragically, they weren’t nearly so lucky.