Nav7: from Archerfield to Goondiwindi

Soon after taking off from runway 28L I left the controlled airspace of Archerfield aerodrome, on my way to Goondiwindi. This marked the start of second leg of Nav7. The first one was recounted here. The last words I heard from the tower controller were "cleared for take off 28L". No notification of leaving controlled airspace, no "frequency change approved" and no requirement to make an airborne report either. That's because Archerfield is a GAAP airport, an idiosyncrasy of the Australian airspace system. A GAAP airport is a non-radar towered airport with simplified procedures designed to catter for high-density General Aviation traffic. And there's no taxi clearance either.

I was now in Class G airspace, but only a few minutes away from entering the Class C controlled airspace of the Amberley RAAF base. Most week-ends this airspace is de-active and reverts to Class G airspace where CTAF rules apply. It's just like any other non-towered aerodrome, just with much much longer and wider runways. The airspace however can become active on very short notice. The consequences of busting controlled airspace, and especially military controlled airspace being dire, I double-checked the status.

I tried to get the status from the Amberley ATIS on the NDB frequency but I couldn't hear much of the recorded voice message over the morse code and the static. So I called Brisbane radar and requested the status of Amberley, which the controller said was de-active. Good. That meant I could track direct to Gatton at 2500ft instead of having to request a clearance and possibly being told to go the long way around the aerodrome via the westbound VFR route. 

I identified the Goodna VFR entry point for Archerfield on my left and kept my eyes out for any incoming traffic. I could already see Ipswich, the Amberley aerodrome and the Swanbank Power House. I kept listening to the CTAF frequency for Amberley and made a few position reports. There was only one other plane on the frequency, a Cessna 172 doing circuits at Amberley. I could now see the township of Marburg right ahead of me in the foothills of the Mt Grandchester range. I climbed to 4500ft and found some light turbulences, a harbinger of things to come.

I kept tracking west to Gatton, which was easy to identify thanks to Lake Clarendon to the north and the highway and the railway both running west. I turned south and started climbing to 8500ft. I had initially planned to stay at 6500ft but later decided to buy myself a bit more safety and gliding distance in the event of an engine failure. 2000ft extra mean about 3 more minutes at the descent rate obtained for the best glide airspeed of 68 knots, which in turn means about 3 extra nautical miles in the glide. Over a mountain range with peaks at 3700ft, this could make  the difference between landing in a paddock in one of the valleys below or having no other place to land than a heavily timbered area on a mountain slope. Did I mention that one of the highest peaks in this area is named Mt Mistake, at 3582ft?

Turbulences were present throughout the climb but ceased suddenly as I passed 7000ft. It must have been the altitude where the temperature inversion was sitting and prevented air heated up by contact with the ground from rising any higher. My best guess is that this was a subsidence inversion caused by the air being pushed downward in a high pressure system and warmed up by adiabatic compression before spreading out parallel to the ground. Yes, I've been reading the CPL Meteorology book recently in preparation for the PPL Theory exam. Anyway, whatever the reason, the visibility above the inversion was just amazing. I could see all the way to Clifton, about 30 nautical miles away.

I was far from any CTAF so I was listening to the area frequency, which was very quiet on this Sunday afternoon. There was a lot of static though, and I couldn't make it go away by using the squelch knob. I made sure the radio was not in the test position which bypasses the squelch. I was tempted to turn the volume down but then I couldn't hear what was being said on the frequency, which is bad airmanship. Then suddenly it dawned on me. I tried using the COM2 radio instead of COM1 and the problem disappeared.

The air coming into the cabin through the ventilation duct started to get a bit colder, reminding me of the temperature when I left home earlier that day. The Outside Air Temperature (OAT) gauge indicated only 2 degrees C. That's the LCD display in the top-left corner of the instrument panel, left from the airspeed indicator. With the rule of thumb of loosing about 2 degrees per 1000ft, this was consistent with a ground temperature of about 20 degrees.

Approaching Warwick I gave a call to the CTAF, even though at this altitude I couldn't interfere with traffic in the pattern. Better safe than sorry. Over Warwick I turned right and started tracking to the south-west and Goondiwindi via Inglewood. 

Lake Leslie appeared just a few miles to my left. I looked at my map and realised the planned track was supposed to take me right over the lake. I was offtrack to the north by a few miles. I did a one-in-sixty calculation which gave me a new heading for Inglewood. By the time I had finished the calculation and turned onto the revised heading I could already see Inglewood in the distance, more than 20 miles away. Damn visibility. Makes dead reckoning navigation too easy, as Australians like to say.

I tried not to look at the GPS at all on this nav, but I still had it on just in case. I had a quick glance. My groundspeed was 81 knots. My true airspeed was around 115 knots, so that's a headwind component of 35 knots, a lot more than the forecasted 25 knots. The problem was that fuel planning in Nav7 is critical. If I had taken off from Redcliffe with full tanks, I would have had barely enough fuel to complete the flight within the legal limits. That's why I refuelled in Archerfield, which increased my fuel margin by 11 litres, or 16 minutes in the air. Now the increased headwind was robbing me of my fuel margin. Not good.

I decided to descent to 6500ft hoping that the winds were weaker there. They indeed were, and my groundspeed increased to 97 knots, 16 knots more than what I was doing 2000ft higher. The increased groundspeed came at a price though. I had crossed the 7000ft level where turbulences had stopped on climb, and they came back with a vengeance on descent. It was very very bumpy. It was like someone was slapping the airplane from the outside. Maintaining altitude within a hundred feet of 6500ft required all my attention and I was not terribly successful at that. I decided to stay at this level anyway since I only had about 20 miles to run before starting my descent into Goondiwindi.

I found the aerodrome right where I expected it, although later than expected. Maybe I should have delayed my descent a little, which would have given me a steeper descent angle and therefore a better view of the area. The fact that the runway 04/22 was nearly parallel with my track of 247 degrees didn't help spot the runway early either.

No-one could be heard on the CTAF frequency. I overflew the runway, looked at the windsock which was favoring runway 22 with a strong crosswind from the right. I joined the circuit and made a descent crosswind landing on this sealed runway. When I turned on final I was surprised by how narrow the runway looked. I looked it up later and realised it is the exact same width as the runway I am used to at Redcliffe. Only that it is double the length, hence the optical illusion that it is narrower. I had just experienced a textbook optical illusion.

I taxied to the apron, chose a parking spot not too far from the terminal and shut down. I tiddied up the airplane only to found that my empty water bottle had halved in size since I last drank from it at 8500ft. The elevation at Goondiwindi is 714 feet, which means the atmospheric pressure is about 250 hPa higher than at 8500ft, an increase of one-third. One more practical experience that confirms what the book says. One thing I love about aviation is that science is never far if one knows where to look.

Nav5: seven controller, a few street lamps and a diversion

The first leg of Nav5 took us from Redcliffe to Gold Coast through the Brisbane Class C airspace. I think I talked to more controllers in the first 30 minutes of this flight that in all my flying training to this day.

Redcliffe being a non-towered aerodrome, my only contacts with controllers so far were during navs to Archerfield, Maroochydore and Oakey. On a couple of occasions I also contacted Brisbane Radar to request a radio check early in the morning when no one was answering on the local CTAF frequency.

We requested a code and clearance from Brisbane Radar, who immediately handed us over to Brisbane Approach. We got cleared for the Hornibrook Viaduct, Brisbane Control Tower and Manly boat harbour at 1500ft.

As we approached the tower, the controller gave us a landing clearance for runway 14. Hmmm... that was very nice of him, but we never intended to land at YBBN, and never asked for a clearance... Before I could think of what to say he came back and corrected his mistake. A minute later we overflew the threshold of runway 01 and I could see three Qantas airliners queuing up at the holding point right under us.

Tower handed us over to approach on the other side of Brisbane airport. We overflew the Jacobs Well VOR, jotted down the ATIS for Gold Coast then switched frequencies again a few more times through approach, tower and ground for Gold Coast. In total, I talked to seven different controllers. My radio calls were good, thanks to careful preparation and quite a bit of rehearsal at home beforehand.


We landed at Gold Coast on runway 32, taxied to the GA parking and started up again soon after for Cherrabah. Gold Coast was very busy that morning, we had to wait for a little while at the holding point. Finally the controller gave us an immediate departure and we took off just as a Virgin Blue 737 was coming in to land. As we departed I glanced back at the runway to realise that, instead of the normal Virgin Blue red livery, this aircraft was entirely painted in blue. Sean explained that this was Virgin Blue’s 50th Boeing 737, and that the names of all employees, including his from a past non-flying job with the airline, were printed on the overhead lockers.

According to Wikipedia, Virgin Blue’s name if a play on the predominantly red livery and the Australian slang tradition of calling a red-headed male 'Blue' or 'Bluey'. So I guess this solves the mistery of why Virgin Blue planes are usually painted red.

We climbed to 6500ft to clear the ranges of the Gold Coast hinterland and tracked for Cherrabah. That was quite a long leg, with spectacular views of the mountains. We identified Palen Creek Prison Farm. Sean tried to convince me to stop doing 'track crawling', i.e. spending my time with my nose in the map in order to always know where I was. Our ground speed was higher than planned, so we entered the open country near Killarney earlier than expected. This threw me off for a moment, then we kept flying the heading and, sure enough, we found Cherrabah a few minutes later.


In the morning when I had called the Cherrabah Homestead to request permission to land, the person on the phone had requested that we overfly the runway once before landing “to scare the roos”. We did one 100ft overfly but couldn’t see any kangaroos. Sean talked me through the approach and landing. Quite a challenging approach actually, with hills on all slides and a sloppy runway.


The airfield is one of those places you have to see to believe. Too bad Shane didn’t get to see it on his Nav5 and got diverted to Warwick and its swarms of flies instead! The runway itself is actually quite nice, it was upgraded from a grass strip to a sealed runway a while ago. Cherrabah is not a licensed aerodrome, so I guess they do not have to comply with too many regulations about runway lighting, and obviously they let their creativity go wild with these beautiful solar-powered replicas of classical street lamps in the Australian bush. The terminal building, although empty, is well worth the picture too.


We took off on 28 and did some low-level flying following a road and a river, pretending the cloud ceiling was so low we were following natural features on our way to Warwick. This is what some people call IFR Flying: I Follow the Road. We then tracked north to Toowoomba, and as we were near Allora we diverted direct back to Redcliffe. I requested and obtained a clearance for crossing Amberley airspace and amended our flight plan.

We flew a few miles south of Lake Wivenhoe, crossed the ranges, kept our eyes out for airplanes tracking south for the "TV Towers" entry lane to Archerfield, found Petrie, the nearby paper mill, then approached Redcliffe from the dead side and landed on 07. We had a thorough debrief during which Sean said that the two things I really had to work on were holding an accurate altitude and heading, so I'll have to make this a priority for the next navs. And avoiding track crawling.

Nav5 was my last time flying at the front of the aircraft for a little while. After that I had two weeks of business travel, half a week of jetlag, some busy days catching up on work, and almost a week of vacations. There was a lot of flying of course, but unfortunately only of the kind that involves sitting at the back of an airliner for more than ten hours in an economy seat that makes the cockpit of a 152 feel like luxury.