Stargazing over the Atlantic

“See? What did I tell you? Piece of old tackie. All they do is sit there and watch the auto-pilot do the flying.” This was the comment by a passenger to his friend visiting the flightdeck on one of my 747 flights from Cape Town to Miami some years before 9/11.

The passenger incidentally, was a commercial pilot with some two thousand hours of flying experience on light aircraft. I knew the non-flying public were ignorant but a statement like that coming from a fellow aviator? Maybe that old saying ‘a little bit of knowledge is a dangerous thing’ was true after all

Actually, ‘driving’ this thing is really easy,” I replied sarcastically. “All we do is push the ‘fly’ button to take off and the ‘land’ button to tell the autopilot to put us safely back on the ground again. Simple isn’t it?”

The passenger caught my drift immediately. “Okay, maybe not,” he apologized. “But what is it you guys actually do up here for fifteen hours?”

That question made me realise that in spite of the fact that aeroplanes have been around for over a century, the public are still completely ignorant of aviation. Ask anybody what a tonsillectomy or an appendectomy is and I’ll bet most people have some idea. Ask them what a fuselage or empanage is and watch the look on their faces. To some people flying is an ordinary as climbing on a bus – to others, it’s a terrifying ordeal. Neither perception is accurate in the objective sense. Considering that you’re strapped into a metal tube moving at nearly a thousand kilometers per hour through an environment that – merely inches away – would not sustain your life for more that a few seconds, this is hardly a bus trip!

But then, given the incredible technology used in designing, building and flying theses machines, and the corresponding reduction in risks; flying should no longer be a terrifying ordeal either. And on a higher level, even professional pilots outside an airline environment don’t suspect how involved a transoceanic flight can be. How come? Maybe the difference between a doctor and a specialist is a fair comparison So, getting back to my passenger’s question. What is so different about flying a wide body jet over the ocean at night compared to any other flight? What do we really do on a 747-400 flightdeck for fifteen hours? Stare at the stars? Well, in reply I’d have to point out that it all starts with the planning – much of which is done by a very capable dispatch and scheduling office. For one thing, on those long haul flights we carry a double crew, the captain and three first officers. This is so the flight can be divided up into acceptable duty periods. One crew sleeps in the bunk directly behind the flightdeck, then rotate halfway through the flight when the operating pilots become tired. This is especially important as the last situation you need is to have a fatigued crew perform a Cat 3 approach onto a fogbound runway at the end of a fifteen hour flight when you’re low on fuel. People have died because of that! The pre-flight briefing is extremely thorough and carried out by professional dispatchers. Their job is to inform us on the status of the aircraft, that is, any technical snags that may be relevant to our flight. Then the regional and long range weather forecast is reviewed along with the Sita flight plan which general aviation pilots will know as the ‘nav log.’ Next, the expected zero fuel weight (ZFW) is given to us. This will influence some of our decisions, as will the nature of the cargo on board. (Dangerous goods for instance could affect a decision in an emergency.) And then of course there is the fuel planning. Now this is a particularly interesting aspect. Unlike a light aircraft where you generally top up the tanks regardless of how much you need, we have to be particularly careful with this decision. You cannot simply fill the tanks! This is because on a jet, the more fuel you carry, the more fuel you burn to keep it aloft and correspondingly the less the payload you can carry. And payload after all, is what makes a flight economically viable in the first place. Above the legal requirements, if you still have space, you can load extra fuel or payload – but not both. An increase in one is a sacrifice to the other, so it is a delicate balancing act. Also, the heavier the aircraft, the lower will be the cruise altitude, the more fuel you burn. Sort of a catch 22, robbing Peter to pay Paul. In the case of the old Miami flight the problem was somewhat different. Fifteen hours of flying while burning ten tons of fuel per hour means we needed 150 thousand kilos of fuel to complete the flight. Then there is the added fuel for the diversion if we can’t land, that’s about another eight tons. Then the thirty minutes of’ holding’ fuel in case we end up having to enter a holding pattern. Chalk up another couple of tons. What about contingency fuel is case of diverting around weather? Better add a few more tons. Oh, and don’t forget, just to taxi this beast to the runway will require at least one ton of fuel.

By the time you add it up, a typical American flight (if you can call any flight ‘typical’) will need between 164 and 174 thousand kilograms of fuel, the difference being the forecast winds and routing on the particular day. (The upper winds are mostly from the west so you can bargain on a headwind for most of the way, only the velocity varies.)

So, there we have it. A fuel decision! But wait! The 747-400 can carry 175 thousand kilos of fuel, but that is only if the specific gravity of the fuel is dense enough. What if it isn’t? What if it’s a warm day? What if the SG is not dense enough and the tanks are volumetrically full, but the weight of the fuel is not sufficient for the flight? What do we do now?

WARM FUEL: The way this problem is solved is quite ingenious. The schedule was designed in such a way that the aircraft began its trip in Johannesburg with a flight down to Cape Town before its trans-Atlantic marathon. This short sector only requires thirty odd tons of fuel, but in fact is loaded with at least sixty tons of ‘tankering’ fuel. Two hours cruising at high altitude in ambient temperatures of minus 50 degrees Celsius was enough to change the density of the tankering fuel to a SG high enough to leave sufficient space in the tanks for the balance of the Miami fuel to be loaded in Cape Town.

Problem solved – for the moment. Now let’s say it’s a warm evening. Hold that takeoff! The air’s not dense enough to support all that weight within the length of the runway. Eventually after a delay we start the takeoff roll at max gross weight, which typically is close to 400 thousand kilograms, and head out northwest over the ocean. The takeoffs are always manually performed; the autopilot only has the capability of performing autolands.

This is the last time we will see land for eight hours until we cross Recife on the horn of South America. Now’s a good time to establish communications on the long range HF radios. Initially we speak to CPT on the HF, then Johannesburg and also ZUR, SAA’s monitoring station. If anything goes wrong at this stage, search and rescue will be South Africa’s responsibility. Later on it will be transferred to Brazil and then to a myriad of other countries before ending up with the USA. For this reason communication is absolutely vital.

SPACE JUNK: As we continue out over the dark void the night becomes incredibly black and yes, the stars (when you have time to study them) are absolutely magnificent! You may even be lucky enough to glimpse the dramatic sight of space junk re-entering the atmosphere or, as I watched in awe one night, the comet Shoemaker-Levy 9 on its orbit around the sun. And you will not believe how may meteorites you can count in a minute. But I digress. The relief crew have dinner and then hit the bunk for a few hours rest. They’ll be woken later over Brazil. As we burn fuel the aircraft becomes lighter and we begin a series of step climbs that will continue throughout the flight, keeping the aircraft at optimum altitude. The fuel-flows start coming down nicely as we climb higher, but all the while we must watch the wind. Generally the wind speed increases the higher we fly so we better make sure that the reduced fuel-flow isn’t compromised by the increased headwind. The forecast wind has a direct bearing on the track planned before the flight. A bit like ocean-going yachts adjusting their course to take advantage of, or negating the effect of, the wind.

Forecasts on the Sita flight plan are uncannily accurate but you can never be too sure, weather still remains an inexact science. On such a long flight it is normal to pass several weather fronts, both warm and cold, along with all the associated thunderstorms and clear air turbulence. Weather radar makes dodging the active cells relatively simple but you must be careful how you do it. If you pass them on the leeward side be prepared for a rough ride.

Navigation itself is done using two GPS’s and three Inertial Reference Systems (IRS) which are highly accurate laser gyroscopes. Reporting points are termed ‘waypoints’ and are simply latitudes and longitudes or prime meridians where radio calls are made on HF and 126.9 in case of other traffic in the area.

The first half of the flight feels incredibly lonely as there are no other aircraft operating on that sector of the route and if an emergency occurs midway over the Atlantic the only alternative is Ascension Island, and even that is a good few hours away. It is only approaching Recife that you start hearing the familiar VHF chatter and pick up the occasional TCAS (traffic collision avoidance system) symbol on the CRT. Talking of CRT’s, the 400 has a six-tube EFIS system and is ergonomically designed making the fuel, hydraulic and other systems extremely efficient for the pilots to manage. On the older 747 classic’s that was the Flight Engineer’s job. The three autopilots can be disconnected at any time but with the management duties taking up so much time, why fly manually except to check the trim? Besides, at high altitudes the air is very thin and the effort required to fly accurately would distract you from your other duties. But what the heck if you really want to, go ahead, fly the aircraft. Just don’t overload the other pilot with your duties because remember, when you are flying manually he has to monitor you!

By now we have comms with Braza and then with Recife, time to check out that fuel. On the northbound sector it should not be a problem as at this stage we have burned almost half our load and if we’re running short we can always divert into San Juan or one of the other islands for more. But on the southbound flight you need to be wide awake as it is the last half of the flight that is over the ocean and if you run short there is nowhere to go!

Crossing Recife you’re tired – time to wake the relief crew. You change seats, brief the fresh pilots on your progress, then head for the bunk. The bunk beds are really great. Completely enclosed in a tiny cabin, it is a little quieter that the flight deck although most of us still sleep with earplugs.

While we are resting the other crew is speaking to Cayenne in French Guiana and Paramaribo in Surinam, then Puerto Rica, radioing ahead for destination and alternate weather. By now the white TCAS targets are becoming more frequent on the screen, which is fine as long as they do not change to amber and then red. If they do, be prepared to take evasive action immediately – there is another aircraft in you flight path! Unlike over Africa, ATC and radar control are generally very good, but don’t bet your life on them. If something happens the ATC will be the one walking away from the accident, not you.

BREAKFAST: The primary crew are woken about thirty minutes before descent and briefed on the expected landing conditions and the fuel situation. Just enough time for a quick breakfast, then a review of the Jepp approach and landing charts before starting the descent. Some airports have complicated arrival and departure procedures, which can be programmed into the Flight Management Computer (FMC), but as with the autopilot, and indeed any computer, it is only as good as the human punching the information into it. The descent is not the ‘hit or miss’ affair it can be on light aircraft either. It would be foolish to start the descent too early, correcting the error with thrust and high fuel flows when you haven’t much more than reserve fuel left. If weather permits, the landings are performed manually, which ironically is far less stressful than setting up for an autoland. This is because autolands are done in really bad visibility and although the autopilot flies the aircraft more accurately than a human, any failure in the systems will require a split-second decision to continue the landing or go-around. Either decision will have serious implications. If you go around you can bargain on burning at least two tons of that precious fuel before you start your next approach. (Better check that you still have enough to get to that alternate airport if you need to). And if you choose to land, make sure you can see the runway, otherwise you are about to make the newspaper headlines! Computers on a modern flight deck are not there to take the responsibility away from the crew. Rather, they make far more information available to them, enabling the crew to make more rational and objective decisions. And these days, that is what this job is all about.

These are just some of the factors that occupy our thoughts before and during a flight. Obviously there are many more, but if you ever visit the flight deck and see the crew staring at the stars, rest assured, they are contemplating far more that just the universe.

The author flew the Boeing 747-400 before being appointed as a Training Captain on the Airbus A340 with SAA.