Flight Impressions – Boeing 747-400

At 175knotsJohn calls “rotate” and I ease the stick back,raising the nose and curving our wings to an exaggerated sailplane-like dihedral as they strain to lift the whole of this vast aeroplane into the darkness. The last of the red runway lights flashes beneath us, leaving nothing in view but random scattered pinpricks of light from the dawdling junks and bustling ferries on the inky water just below As our immaculate new Boeing 747-436 soars majestically out through the Lye Mun Gap between Hong Kong Island and the mainland we know that few wi11 notice our passing, for we are quieter than earlier Jumbos, and climb much better. Even at this, our maximum structural weight,our climb rate exceeds a thousand feet per minute, yet we have used less than full thrust for takeoff.

Twenty years ago I started my professional flying career wrestling with the manually activated controls of another 436, BOAC’s variant of the first practical jetliner, the 707. This vastly more refined piece of equipment I fly today is its direct but almost unrecognisable descendant. Now I am privileged to be a co-pilot on this most capable airliner, British Airways’ Boeing 747-400.

I have to admit that when I transferred to this fleet from the old ‘clockwork and steam’ 747s I did so with more than a little trepidation. Electrics and electronics are not my scene and I am not computer literate or even familiar (a man after my heart! Ed). A mechanically minded man, I do not trust erratic electrons or wild wiggly ampsand found the wiring diagrams on the motorbikes of my youth mystifying, so what on earth was I doing coming to the world’s most advanced complex aircraft with 220 kilometres of wire and 4. 5million separate parts.

With all the other wide bodies around today it is easy to forget that back in the sixties when Boeing first designed the 747 they were making a quantum leap in size. Wisely deciding not to take any other risks they stayed with proven, if dated, technology throughout. Having simply stretched the design twice, with the advent of improved structures and electronics and when more powerful yet more economical versions of the Jumbo’s engines became available, this time they decided to go the whole hog and revamp it from its shadow up.

Drawing on experience gained from the first generation flight management computers and electronic instruments in the 757and 767, they incorporated much more sophisticated units and simplified and automated the systems so that they could dispense with the flight engineer needed to operate the antiquated equipment on the ‘classic’ 747.

The result is an integrated display of all the information that pilots could possibly want,in easily assimilated form, eliminating anything irrelevant to the current phase of flight. Each crewmember has a pair of big screens, the most important being the Primary Flight Display (PFD) which fulfils more functions than nine of the old,round dials, although not all at once. Aswell as attitude, altitude, direction, speed, mach, ILS, markers, radio altitude and autopilot status, the screen gives trends of the important parameters, maximum and minimum speeds for the current configuration and pitch guidance in the event of windshear.

The quality of information is improved too, with inertial-derived instantaneous VSI (vertical speed indicator) and a compass that has no unreliable magnetic sensor but combines its current known position, true heading and stored local variation to give a digital readout accurate to a tenth of a degree.

The second screen, the Navigation Display (ND), can be selected to show basic compass superimposed I LS (instrument landing system) or VOR beam bars, a ‘north-up’ plan of the route to be fl. own or, most frequently, a variable range, ‘track up’ map of the next few waypoints. Included are the selected VORs or NDBs (navaids still much in use outside of Europe), with their automatically naurally checked idents, and DMEs.

Also incorporated are navaid needles, an instantaneous wind diagram and the next waypoint’s range and ETA. Optional functions include ETAs at all waypoints, off route points, and the positions of nearby beacons or airports, although these are strangely defined, including several grass and STOL fields but not some international destinations. The whole can be overlaid with the weather radar picture until this is replaced by the projected collision avoidance system later in 1992.

Primary engine parameters and computer generated warnings of any equipment abnormalities are displayed on the upper of the two central screens, while secondary engine information and detailed system flow diagrams can be summoned to the lower one if needed. Flight profiles are suggested and executed by dual Flight Management Systems (FMS) and three Inertial Reference Systems (IRS) take care of accurate navigation.

An excellent man-computer-machine interface is completed by the superbly able and smooth triple autopilots 111:ttl efficient,accurate autothrottle to make this the most ‘pilot friendly’ aeroplane imaginable – a necessity when you consider such a complex aircraftis flown byjust two crew who may need every byte of automation when the going gets rough.

Those fliers among our readers who use a written checklist for every cockpit operation may be intrigued to know that on a two crew airliner (even this very complex one) all normal procedures are actioned from memory. They are then checked with the checklist. Particularly,the nine emergency checklists are done by recall welcome improvement over the 32 memory drills needed on the old 747 The 747’s structure has been improved too, using composites and lighter, stronger alloys, a refined wing section, greater span and the easily recognisable new two metre high winglets for a drag lowering high aspect ratio. Extra 10,400 litre tailplane tanks and more economical, more powerful, digitally controlled engines increase both max takeoff weight and range. The whole reason for this aircraft’s existence is to transport a generous payload over enormous distances and while Howard Hughes’ Spruce Goose is bigger and Lockheed’s lumbering Galaxy heavier (at least it is when empty – at top weight the -400 grosses 55 tonnes more), these are not the important statistics. Aircraft are used purely to carry a given payload, at high speed over great distances so the vital numbers are how much payload, how fast and how far. The smaller and lighter the airframe to do thejob, the more efficient it is. The -400 has a maximum zero fuel weight of 247 . 2 tonnes so it can carry up to 71 tonnes of payload and travel six thousand miles at the same time.

Otherwise can take the full 174 tonnes of fuel- which it usually does- allowing carriage of 386 passengers in exceptional comfort, their bags, and freight too, along with seventeen cabin crew to cosset them and two, three or four pilots to transport them over eight thousand miles at speeds of up to . 88 mach (530 knots). This is faster than any current jet transport other than the Concorde. Indeed an oriental Jumbo has been supersonic, although not intentionally.

With 23 of the type, British Airways already possesses the world’s biggest fleet of -400s and will progressively replace its older 747s with this new aeroplane, of which it has a total of 88 on order including options, but at the moment the -400s are mainly being used on the ultra long haul non stops between London and Tokyo, Hong Kong, Singapore, Bangkok, (and then to Australia and New Zealand), Johannesburg, Rio de Janeiro, Buenos Aries, Sao Paulo, Madras, Kuala Lumpur and the US West Coast. Despite being designed for two pilot operation, these very long flights need a reliefcrew as well so a pair of rudimentary bunks are provided in a compartment aft of the flight deck for those off duty while the stewards and stewardesses have their own ‘loft dormitory’ above the aft toilets. I hear that some crew members have become so used to the bunks they have modified their home beds to resemble them to ensure continuity of slumber.

Spending over two hundred days abroad each year, a long range flier’s whole life revolves around his job so -400 pilots tend to give a lot of thought to their sleep, its quality and length. The machine’s phenomenal endurance means many long nights out of bed, and mammoth eight hour time changes have to be coped with every week, as do indigestion, shortage of exercise and occasional bouts of tummy trouble. Other disadvantages include vitamin deficiency from living off reheated aircraft food, a cramped workplace, low oxygen levels and almost zero humidity, leading to serious and almost constant dehydration (which in turn causes premature ageing).

The benefits of our career are rather more obvious. For me, short haul flying was like running up a down escalator- you work hard all day to end up back where you started- while a long haul pilot actually gets to see something of the world. Injust one month I can sample the delights of North and South America, Africa, the

Far East and Australia (if I can stand the jet lag). Not for me the humdrum home-in-time-for-tea existence of my one continent colleagues. But by far the biggest reward on this fleet is the aircraft itself. It has tremendous built-in systems redundancy and is surprisingly reliable. This big beauty is a really super aeroplane to fly, too – much the nicest of all the Boeings I have flown – its raw performance and honest, responsive handling give no hint of its colossal size and it has enormous control authority.

Flying fast, flaps up, roll control uses small inboard ailerons and spoilers, supplemented by large outboard surfaces at lower speeds. These give it a remarkable 60 degrees per second roll rate. The elevators are equally effective, but quite heavy in steeper turns and at high speed (which is as it should be when people are walking about behind you). The only tricky characteristic is speed stability on the approach, very small pitch or power changes result in big changes, and make hand flying hard work after a long night.

The crisp controls are a true credit to Boeing aerodynamicists and engineers since the aircraft feels and responds much the same throughout its huge operational weight span, from a practical minimum ofjust under two hundred tonnes to almost double at nearly four hundred tonnes. Because of this great weight range there is a broad spread of stall speeds, but the -400s low speed character is nothing short of amazing and completely unexpected for a high speed, swept wing jet.

At 260 tonnes and ten thousand feet, clean and with idle power, genuine airframe buffet starts at 203 knots, increasing after twenty seconds to teeth rattling magnitude at 180 knots when_ the stick shakers start clattering. With a ten degree pitch attitude roll control is still fine and, unlike older jets, to recover you simply ease the back pressure and slam the throttles to the forward stops. Digital fuel controls respect the limits and these incredible engines wind up instantly for a real kick-in-the-back return to normal flight.

Like all Boeings, the 747 has extremely efficient high lift devices.

Ten degrees of the triple slotted Fowler flaps and full span variable camber slats (built in Australia by HdH) reduce stall speed by a whole forty knots to 138 at fifteen degrees pitch attitude. Drop the nose by five to ten degrees and whack on full power to see it recover almost immediately in 150 feet- less than most lightplanes Even with an engine failed this beauty is a big pussycat. One would expect the sudden loss of 58,000 pounds of thrust displaced seventy feet out on one wing to cause a terrific swing, but with so much fan inertia the engines take a while to run down, giving plenty of time to feedin the very effective rudder and keep straight while the aeroplane’s own momentum helps it continue in the original direction. There is an enormous surplus of power available, so the three engine climb rate is still good. In fact, although almost all takeoffs are at maximum weight, we nearly always reduce thrust below full power to prolong engine life – already 15,000 hours. The least we are allowed is three quarters of full power, and on a ‘short’ Atlantic flight that is all we will use -and still she goes up like a rocket.

It is a great shame on such a sweet-flying aeroplane that I have only been able to make eight landings in the last six months because of the legal constraint of a hundred flying hours in each 28 days with sector lengths up to fifteen hours, and the need to act as relief crew half the time, which place a finite limit on the landings available, even if the weather is good enough for an autoland to be unnecessary. Getting a go becomes a big event!

So it is with mounting anticipation that, after our fourteen hour voyage from Hong Kong, I look forward to the eventual landing at London’s Heathrow despite the forecast of a cold front with its associated heavy cloud, strong wind and rain at our ETA. The -400 has a generous thirty knot crosswind limit but such weather is hard work for tired pilots so we have monitored UK actuals throughout the flight on RAF West Drayton’s indistinct and staticridden HF transmissions. On arrival our original forecast would be nearly twenty hours old and no more than a rough guide to possible conditions.

But as we descend over the Thames Estuary we find that the front has moved through to leave a clear spring morn. Gritty eyes still appreciate the sight of the rising sun quickly warming the newly awakened earth below. Ahead, crisply transfixed into three stark dimensions are the angular black, white and grey blocks of London’s still slumbering City – half a globe but just one long night away from far, humid Hong Kong.

In British Airways the non landing pilot, today the captain, flies

the aircraft to decision height so I operate the radio and complete the checklists while watching him manage the descent and approach which, for reasons of economy and safety as well as quietness is made in a continuous glide from cruise altitude. Add the RB2lls’ high residual thrust to the -400’s extremely low drag and you get a very efficient mega sailplane. The trick is to think ahead, ever watchful eyes on both descent proflle and the instantaneous wind diagram at the top of the ND.

The electronics can further help by depicting energy circles, with and without drag, around a chosen point but these have their limitations so intuition and experience arejust as important. Having tuned and identified the ILS for us, the ‘black boxes’ also display its ident with DME on the upper left of our PFDs, but we check them and the ADFs aurally too, to be certain.

Intercepting the ILS, John calls for gear down, twenty flap and the landing checklist while reducing speed to 160 knots for final approach. The triple digital autopilots can follow the beams better than us – down to a full no-decision-height autoland and autorollout if the weatheris really foggy and the destination has a good enough ILS – but they can’t anticipate and don’t need practice. Neither do they derive the satisfaction from controlling the aeroplane that we do.

So with the wheels locked down and checks complete, passing a thousand feet I take over control, disengage the automatics, correct for the changing wind, and begin to get the feel of the aircraft. Thirty degrees offlap are available for landing, but unless the runway length is limiting we routinely usejust 25 to minimise noise and fuel burn. At 155 knots with this setting the aircraft is near its minimum drag speed and is quite ‘slippery’, so early and accurate thrust changes are needed. Controlling speed within the required knot or two needs very small thrust lever movements and much concentration.

Manual decision height is 200 feet above the threshold – just where our 200 foot span wing comes into ground effect – so as I call “land” to the captain’s challenge “decide” I have to exert a small but positive forward pressure on the stick to keep us coming down the slope.

Nearing the ground the radio altimeter’s electronic voice intones “hundred, fifty, thirty” and I make the slightest of flares while easing the thrust levers closed and, like the regal lady she is, she majestically kisses the ground – only to be let down with a bump by her upstart spoilers as usual. The autobrakes and reverse gently bring her to a halt in two thirds of the runway and we turn offto deliver our tired but happy passengers to the staff waiting for them in our terminal.

Despite the quite incredible level of its automation and the sophistication of its controls and instruments – and partly because of its phenomenal endurance-no flight on this aircraft is ever boring and every trip is an adventure. Its handling is a delight, its capability is unsurpassed and its crews are dedicated, professional and cheery. Nothing short of ill health would seduce me away from my new love, Boeing’s latest and most profitable aeroplane, the new Queen of the Skies – ‘The Wonderjet’