Flying the South Atlantic
The South Atlantic Ocean is one of the largest areas of uninhabited space on the planet. Whereas the North Atlantic has an organised track system for commercial traffic to fly across, arranged in parallel lines 60nm apart, the Southern half of the ocean has so little crossing traffic that there is no need for the same provision. Most of the flying is done in straight lines across the chart with points of Latitude and Longitude used to plot the route. Some of these positions are 350 nm apart and perhaps more. All of the radio transmissions are on the long range HF system which is notoriously difficult to use and some of the radio stations seem to have little input into our flights. We are very much left to our own devices out there, which is why our procedures are so stringently adhered to.
A few years ago I was engaged in flying in this remote region of the world on the B767–300ER and while doing so it gives you a different perspective on life in many ways. Naturally the first thing that you notice is the vast distances between airports and the complete remoteness of some of the destinations. Of course it is winter in the southern hemisphere at the moment, so the weather combines to make life more than a little challenging at times. Add to this the fact that communication is difficult at every level and you get some idea of the problems faced by the crews down there. When discussing airline flying in this region, thoughts automatically turn to the loss of Air France 447 which was en-route from Rio to Paris. It was such a terrible tragedy of course, but even more of a shock to those of us working in the industry that an airliner could apparently break-up mid flight due to weather. (As was proven eventually, the prime cause of the accident was pilot error after encounter with bad weather, icing and turbulence).
It certainly concentrated the minds of me and my First Officer (F/O) on one of those flights in the middle of the night when we had a very large band of huge embedded storms which lay across our intended route. The tops of these large Cumulonimbus clouds (CBs) were around 45,000 feet and due to the aircraft’s gross weight our optimum cruising altitude was FL350 (around 35,000 feet) so we couldn’t climb over them.
…so the weather combines to make life more than a little challenging at times.
At one stage we were something like 80nm off our track and working hard with the weather radar to find an easy route through the storms in moderate turbulence. The Fasten Seatbelts signs remained on for a very long time and no doubt there were some of our passengers who were having trouble sleeping. In fact there was no problem for us in staying awake, as we carefully snaked our way round the heavier (Red) returns on the radar screen. As I was Pilot Flying (PF) I asked my colleague to put the engine ignition systems to “Continuous” setting and I set the autopilot speed to M0.78 which is our recommended speed for turbulent air penetration. Our normal cruise speed in the B767 is M0.80 or thereabouts, decided by the Flight Management Computer (FMC) when all the winds, weights and temperatures are fed in to it. The FMC then computes the most economical cruising speed, (ECON CRZ).
….usually I am pretty busy concentrating on flying the aeroplane.
Even though the autopilot is engaged in these conditions, I am always in the habit of following through on the flying controls and therefore we were both sat forward in the flightdeck with full harness applied. Additionally the cockpit and instrument lighting was dimmed to enable us to observe areas of the sky outside for lightning activity. I was anticipating that we would get St Elmo’s fire on the windscreens, but this didn’t happen. I have seen it many times before and the visual effects are most dramatic, although it is a harmless by-product of atmospheric conditions in some weather systems that we fly through. It appears as spidery electric blue miniature patterns of lightning on the inside of the flightdeck windows and according to my colleagues, if you point your finger at the glass and move towards the screen, a small flash of electricity will jump the gap on to your finger! Quite honestly I have found it far too spooky to try this myself and usually I am pretty busy concentrating on flying the aeroplane.
At temperatures below -40, all the cloud particles are assumed to be ice crystals.
Talking of which, I recall that as we approached the band of CBs across our path, we warned the cabin crew to expect turbulence on the intercom, but even we were surprised at how bumpy the ride was. We monitored the outside air temperature closely, because at these latitudes (close to the equator) even at cruising altitude it can warm up to higher than -40 degrees Celsius. At temperatures below -40, all the cloud particles are assumed to be ice crystals and therefore not a danger to us, but once it gets higher than -40, we require to use the engine Anti-Ice systems which direct hot air to flow from the engine ‘bleeds’ to the front intake cowling to keep it free of ice. In common with other aircraft, ice and engines do not mix well! A regular check of the windscreen wiper arm just outside the window is also carried out as this is our first indicator of airframe icing. The detrimental effects of airframe icing on aircraft are well proven and these checks are very important to us — at night we use a torch to shine out from the flightdeck to see the wiper. Fortunately on this trip, we managed to avoid getting ice on the wipers. On the flight before however we were forced to fly through a heavy snow shower during the initial approach phase to reach our destination airfield and noted that we picked up a lot of ice on the wipers very quickly.
When it comes to airframe icing, the Boeing is well equipped to deal with such unwelcome accruals. Along the leading edges of the wings and stabiliser (tail plane) there are fitted large air ducts through which can be ducted very hot air from the engine bleeds which will melt the ice which is formed here. On other airliners which I have flown it is actually possible to see something of the leading edges of the wings from the cockpit and there is nothing better than watching a whole load of ice being shed in chunks as the Wing Anti-Ice (WA-I) system is switched on. It is much preferred to leave the use of the WA-I until there is definitely plenty of ice on the leading edges. If you hit the switch too early, the ice just melts and the water then runs back on to the wing surface to refreeze at a point on the aerofoil section behind that which is capable of being de-iced… The potential consequences of this are obvious.
Even outside the CBs, we found ourselves bouncing around in the tops of the large Cumulus clouds and this we could tell by checking every once in a while with the landing lights. As 500mph fog coming at you can be a distraction, these were only used momentarily to check whether we were in cloud or out of it. From time to time we began to see more and more of the star constellations above us and this gave us much cause to celebrate. The weather radar was showing fewer clusters of red on it and we were finally able to regain our track having added possibly as much as 200 nm to our route. In the overall scheme of things however this is small beer, as on this occasion our flightplan was over 3000 nm long!
We monitor the emergency frequency 121.5 on one of our VHF radios and also the information (chat) frequency 123.45 on another while flying at cruise altitude. On top of this we regularly try to maintain radio contact with the ATSU agencies which allegedly cover large sections of the South Atlantic. However the only station which is really of any use to us is aptly named “Atlantico” which I think is based at Recife on the Brazilian coast. To give an idea of how big the sky is down here, you only have to consider that in an eight hour flight, we maybe only ever hear one other aircraft on the radio and never see any contacts on our TCAS system. Even though we are on a ‘random track’, our standard operating procedures recommend that we fly an offset of 1 or 2 nm to the right of track as one more precaution against meeting somebody coming the other way at the same cruise flight level.
After passing through the weather and with dawn slowly breaking in the East we passed close to the area where flight AF447 went down. We were very quiet for quite some time in the flightdeck after we had noted our location and ruminated on their fate. The size of the task of looking for the wreckage also came to mind as we looked down at the Atlantic and realised that the vital flight data recorders might never be found. If the sea is 12,000 feet deep here as they say and the area to be searched is as large as reported, then the search team are going to have to be spectacularly fortunate to recover the FDRs. (Indeed the search for the FDRs was completed successfully in April 2011, nearly two years later. The wreckage of the aircraft was lying in 13,000+ feet of water…)
Only another couple of hours later and we were on final approach to land at Ascension Island after a long and tiring night. This was to be a crew change stop and refuelling before another equally long journey for our passengers from Ascension to the UK. In the meantime my crew and I would be able to take life easy for a couple of days of well earned rest.
After landing, I and the F/O happened to bump into the ATC tower controller who had popped down to the airport operations room while the aircraft was being turned round. The tower controller was a nice old American guy called Bill and we loved to tease him on the radio sometimes, I think he likes our ‘British sense of humor’. It was good to see him and he asked about the brightness of the PAPIs** which we had asked to be increased on our final approach, “Oh, Hey! They were FINE Bill”, we said, “but could you have the angle sorted out for us please?”
He paused for a moment and then said.
“Whatd’ya mean guys? Ain’t they set right for ya? They should be at 3 degrees right?” to which we came back with,
“No Bill, they are supposed to show us 2 reds and 2 whites, but they keep changing while we’re flying the approach… you need to get that sorted out!”
He chuckled as the penny dropped that he was having his leg pulled again and responded.
“No boys! THAT’S YOUR JOB! You gotta keep ’em two reds and two whites yourself!”
We feigned mock amazement and shook our heads as if we had learned a valuable lesson, “Gosh! Is that how they work?! Well that explains EVERYTHING!”
© James McBride, Ascension Island, South Atlantic Ocean
**(PAPIs — Precision Approach Path Indicators at the side of the runway, normally sited at the 1000 foot point where the airliner should touchdown. On an ideal 3 degree slope approach they should show 2 reds and 2 whites, going low on the slope brings more reds and going high on approach makes more whites).