"Boeing 737. The Next Generation." (Part One)

Somewhere across the globe a Boeing 737 takes off or lands every 5 seconds and over 1200 of their compatriots are aloft at any given time. With the 7000th aircraft rolled out in December 2011, the 737 has truly brought the term ‘prolific’ to airliner production and considering the maiden flight of the 737-100 took place in 1967, it is quite appropriate that the latest metamorphism be dubbed the “Next Generation”.
 
With its title clipped to the more easily handled, “NG”, the ‘next generation’ covers the -600 through to the -900 series of the 737. Of Boeing’s latest offering the 700 and larger 800s have gone on to dominate the skies, while the ‘Max’ is still yet to come. The NGs predecessors, the -200, -300 and -400 had provided the backbone of short haul travel in a very similar way. Whilst the number of earlier models is ever dwindling, they have gone on to be referred to as ‘The Classics’ as they reflect a last bridge between the analogue and digital flight deck. Whilst a highly visible transition, the clocks and dials are but one area of many in which the Classic has been superseded.

737 Next Generation Development:
 
The 737NG program was launched in 1993 under the title of 737-X. Boeing recognized the time-tested qualities of the type, but needed to bring the efficiency of new technology and systems to its most enduring machine. Fundamentally, the 737-X was to fly higher, farther, faster and more fuel efficiently than its predecessor without evolving into a new machine requiring a new designator and certification. A challenging task to say the least.
 
Much of the efficiency revolved around the redesigned wing. With 25% more total surface area and potentially 30% more fuel capacity, the new wing has much to offer. Boasting a higher span than the Classic, the new wing is a more swept with a constant angle of sweep and double-slotted continuous span flaps. Gone is the double swept leading edge and characteristic ‘kink’ of the earlier wing. Similarly, there have been changes to the leading and trailing edge flaps that have resulted in weight saving as well as aerodynamic efficiency. For all of the improvements to the aerofoil and lift augmentation devices, the most visible change to the wing and the aircraft generally, is the emergence of blended winglets on the 737.
 
The smooth, upward sweeping fairings at the tips stand a prodigious 2.4 metres and increase the span by a metre and a half. Simply put, the winglets benefit the aircraft through the reduction of induced drag and consequently improved operational and economic performance. Whilst yielding an impressive 4% saving in mission block fuel, the winglets also increase the 800s range by over 100nm. (Source: Boeing) Improved performance out of ‘hot, high and humid’ airfields is another advantage of the blended winglet. In fact, this aerodynamic device has proved so successful that it is now being retrofitted to 757s as well as 737s.

                                                          The Flight Deck of the Boeing 737-800.

 
The NG also sees the introduction of GPS to the 737 navigation system. Previously only equipped with dual Inertial Reference Systems (IRSs), the system relied upon ‘updates’ from ground based VORs and DMEs to continually refine the aircraft’s present position. Without such updates, the pictorial presentation on the map display could be inaccurate requiring the crew to heavily rely on ‘raw data’ from conventional radio navigation aids. GPS provides a far more consistently accurate map display for the crew and allows for more integration of the aircraft’s Lateral Navigation (LNAV) and Vertical Navigation (VNAV) systems. Additionally, the NG is equipped with a Predictive Windshear Warning and Enhanced Ground Proximity Warning System (EGPWS). This ‘forward-looking’ form of the original GPWS provides improved terrain clearance by such mechanisms as Terrain Clearance Floor, Look Ahead and Runway Clearance Floor algorythms.
 
Efficiency and costs savings can also be achieved on the ground. Production line improvements saw the final assembly of a 737NG in a record-breaking 11 days in 2005. On the maintenance side, the NG was developed with an eye to reducing airframe maintenance costs by 15%. Comprised of significantly less parts than the Classic, the NG was also designed with far more ‘ease of access’ for maintenance crews. Redesigned leading edges, landing gear, electronics, APU and the 15% more efficient CFM56-7 engines all contributed to the bottom line. In conjunction with improved maintenance documents, corrosion prevention and extended scheduled maintenance intervals, the 737NG has won the battle of the dollar over its forerunner.

On the flight deck, the 737NG strongly resembles its twin-engined big brother, the Boeing 777. The panel is dominated by the presence of 6 LCD panels arranged side by side, replacing the combination of EFIS and analogue that was found on the Classic. For the pilots, this means a degree of modification of their instrument scan from the vertical to the horizontal. The flight deck was designed in response to the demand by operators that a new type endorsement not be needed. As a consequence, the overhead panel closely resembles the Classic with its array of toggle switches and dials, though the operation of the system behind the switch may well be different.

                     A QANTAS Boeing 737-800 awaits its take-off clearance as another 737NG comes 'over the fence'.

 
As for achieving higher, faster, farther and more fuel efficient performance; Boeing delivered. The NG possesses greater range by more than 400nm over the earlier model, whilst topping out at FL410 (41,000 feet) as opposed to the Classic ceiling of FL370 (37,000 feet). With a typical cruise speed of 0.78M and a sprint capability to 0.82M, the NG draws away from the Classic’s average cruise of 0.745M, whilst all the while burning less fuel. Furthermore, depending on the cabin configuration, the -800 can achieve all of this while carrying around 40 more passengers than its predecessor. From humble beginnings as the 737-100 nearly 40 years ago, the 737 has kept pace with the times through ongoing development and improvement. The 737NG is no exception.
 
Technologically, some 737 NGs can be equipped with a ‘Head-Up Guidance System’ or ‘HGS’. The HGS 4000 system features a transparent drop-down screen in front of the Captain on which is projected an array of flight information, allowing the pilot to operate in lower visibility situations than would otherwise be possible. Head-Up Display (HUD) technology has been available for years on military aircraft and Alaska Airlines started flying HUD on their 727s back in the mid-80s and all of their 737-400s are equipped with the technology.
 
Some airlines have opted for the Vertical Situation Display (VSD) on their aircraft. The VSD displays the current and predicted flight path of the aircraft and indicates potential conflicts with terrain. The VSD is designed to enhance situational awareness on the flight deck and is yet another way in which the Next Generation is offering advances over its predecessor......

Check back later this week for the conclusion to "Boeing 737. The Next Generation."

"Late in the Day"

                    "Traffic Ahead." A very popular image on the blog this past week.

Hi All,

Thanks once again for a tremendous week at this aviation blog. Your support just keeps on growing!

The choice of highlighting the most popular blogs is getting more difficult each week as the numbers seem to be rising right across the range of stories. In a news sense, the post on the collapse of 'Air Australia' seemed to strike a nerve. As a series, 'The Practical Pilot' seems to be very popular, so you can be sure that more of that style of content will be on its way. Similarly, the second instalment of 'The Fatal Stall' inspired quite an amount of comment and feedback; particularly given the fate of Air France 447 in more recent times.

I would like to humbly thank Karlene Pettit for mentioning this blog and profiling me at her very popular website. I also received my copy of her book, "Flight for Control", in the mail a couple of days ago and I recommend that you check it out at her website also.

Episode 82 from the lads at the PCDU podcast hit the airwaves where we chatted about topics like 'The Fatal Stall' and the recent Air Test of the GippsAero GA8 for 'Australian Aviation' magazine.

Well, you've probably grasped that it's been another busy week and I'm currently organising content for the seven days ahead. It's a significant task, but the ongoing support of this aviation blog is making it all worthwhile.

Please keep the feedback and comments coming and don't forget to subscribe to this website or 'Like' me on Facebook.

Cheers for now,

Owen

                                        Three de Havilland Tiger Moths put on a show.

Hi All, here's something a little different today.....

The De Havilland aircraft company had a fine tradition of civilian training and touring aircraft prior to the outbreak of World War Two. From Humming Birds and Hornet Moths to Dragons and Albatross, the British company produced a vast range of machines. At the upper end of the speed spectrum was the twin-engined monoplane, the DH88 Comet. Manufactured from wood, the Comet blew away the competition in the 1934 MacRobertson Air Race from the UK to Australia, though just as significantly, it planted the seed for a revolutionary military aeroplane. The DH 98 Mosquito.

The Mosquito was originally conceived as a high speed unarmed bomber. In 1940 with Great Britain facing its darkest hour and a shortage of resources, it needed aircraft and it needed them quickly. Though the Air Ministry had some reservations about the unarmed aspect of the design, it could not argue with de Havilland’s expertise in wooden aircraft production techniques. Additionally, the fact that its construction called for minimal amounts of treasured metal resources offered up a viable alternative.

After a series of changes in the aircraft’s perceived role, the original order was modified to a requirement for 20 bombers and 30 fighters. The prototype initially built in a hangar disguised as a barn at the home of de Havilland, Hatfield. It narrowly missed being destroyed during a successful Luftwaffe bombing raid on Hatfield that did spell the end of a number of materials and over twenty people. However, the Mosquito survived and undertook its maiden test flight in November of 1940 at the hands of Geoffrey de Havilland’s son of the same name. During the subsequent trials the Mosquito’s speed established it as the fastest combat aircraft on either side of the conflict; a title it held for the next two years.

Into the Fray.

The Mosquito’s first operational sorties were in the role of Photo Reconnaissance (PR) in August 1941, a task it was ideally suited to with its high speed. Early in 1942, the aircraft began to see service as fighters and bombers. The Mosquito had far exceeded the original specifications and through minor modifications was able to carry 500 pound bombs in place of the originally planned 250 pounders. The first bombing raid was a daylight strike on Cologne after a “1000 bomber” raid had taken place the previous evening.

The versatility of the Mosquito became apparent and aside from being a fighter, bomber and photo recon aircraft, it successfully served as successful night-fighter and even participated in the “Hunter/Killer’ pairing of Turbinlite operations. The Mosquito was also extensively used in the precision-navigation role of ‘Pathfinder’ where it would fly in advance of the main bomber force to mark the target with incendiary ordinance. BOAC (the forerunner to British Airways) even used civilian registered Mosquitoes during the war to run the gauntlet between Britain and neutral Sweden on a regular air service. There seemed very little that the Mosquito could not do.

Special Roles

In its time, the Mosquito was called upon to fill some rather niche roles that have gone down in folklore. Two of these were 618 Squadron’s use of the bouncing bomb ‘Highball’ and the breaching of prison walls in ‘Operation Jericho’.

While much has been written of Barnes Wallis’ bouncing bomb and the Dambusters raid on the Ruhr Dams, there was an alternate deployment of the bouncing bomb planned for use by the Mosquito. This version of the bomb was known as ‘Highball’ and while the Dambusters used a cylindrical style bomb, ‘Highball’ was far more spherical.  Also conducted under a great veil of secrecy, 618 Squadron was tasked with using the bomb in an anti-shipping role with its number one priority the sinking of the German battleship the Tirpitz. Unfortunately, despite all of the effort and training, 618 Squadron never had a shot at the Tirpitz and eventually the squadron was deployed elsewhere.

A task for the Mosquito that did see notable fruition was ‘Operation Jericho’. Conceived in 1943, this mission involved an attack on the Amiens Prison in France which was holding amongst others, numerous members of the French Resistance who were scheduled to be executed. The daring low level attack took place on the 18th February 1944 and included squadrons from the RAF, RAAF and RNZAF. Its plan was to destroy the prison walls to facilitate the escape of the inmates, with an alternate plan of destroying the prison outright should this fail. It did not, and while there was loss of life, hundreds of prisoners were able to escape.

The Numbers

To quote specifications for the Mosquito is akin to comparing racehorses; there are so many types and so many variables.

In essence, the Mosquito was a twin-engined combat aircraft of primarily wooden construction. It was operated by two crew, including the pilot, and whether the second crewman was a navigator, bomb aimer or radar operator was dependent upon its designated role.

Powered by two Rolls Royce Merlin engines, it could carry nearly two tonnes of bombs deep into the heart of Germany. As a fighter it could carry 4 × 20 mm Hispano cannons in the fuselage and 4 × 7.7 mm (.303) Browning machine guns in the nose. Some photo reconnaissance versions had a service ceiling of 40,000 feet and a number of marques had a top speed in excess of 400 mph.

Ultimately, nearly 8,000 Mosquitoes were built and of these around 6,700 were delivered in wartime. As an aircraft it was not purely versatile, it was truly prolific as well.

The End.

As with all types, a number of Mosquitoes met ignominious ends on scrap heaps at the end of the war. However, several models survived and the Mosquito production line remained open until 1950. They saw service with air forces around the world and saw action with the Israeli Air Force during the Suez Crisis. A less adventurous tasking involved duty as target tugs while others took to the seas as a carrier-borne variant sporting folding wings.

To the very end, the Mosquito continued to fill roles that no other aircraft could. The model continued onto the Mk. 43 which was a trainer with the RAAF, but there were so many variants and marques before the final propeller stopped.

I had the pleasure to be interviewing a ‘Battle of Britain’ veteran who in 1942 received a new posting to a Mosquito squadron with some trepidation. He had heard very little of the new type other than the fact it was wooden and therefore seemingly a backward step in fighter technology.

He went on to fly the Mosquito more than any other aircraft and commanded a Mosquito squadron post war. He never lost his affection for the ‘Mossie’ he grew to love and sixty years later still had a twinkle in his eye when remembering de Havilland’s “Wooden Wonder”.

Hi All,

As the numbers continue to soar on this blog and a new group of readers join us, I thought it would be worthwhile to re-visit five of the most popular aviation blogs thus far. Here they are.

1. Golden Days.

2. So You Want to be a Pilot?

3. The Fatal Stall.

4. A Glimpse of the 'Red Tails'.

5. The Big Bang Theory.......of aircraft engines.

For those of you new to this aviation blog, welcome aboard! And for those that are continuing to come back, thanks for your support and please enjoy the growing list of original content.

Cheers

Owen

In 1994 I was a very junior First Officer in the process of completing line training with the now ‘late’ Ansett Australia. To my left sat one of Ansett’s most experienced training Captain’s on the 737 who had been on the type since the earlier -200 model had been introduced. I was to be the pilot flying on the sector, a simple hop from Melbourne to Adelaide with clear skies and fair winds, ideal for a ‘bog rat’ like myself attempting to master my first RPT jet.

Cleared for take off on runway 27 I pressed the TOGA buttons to bring the aircraft to life. The autothrottles promptly advanced, hunted a moment for the correct N1 and then held steady. Through “80 knots”, “V1” and “Rotate”, the 737-300 eased into the sky with a minimum of effort. I called for gear up and seemingly no sooner than the undercarriage had nestled into their respective bays, we heard a ‘thump’. Wonderfully indistinctive, the sound was significant enough to be met with a mutual and instantaneous turn of our heads. This was followed by one of those dreaded flight deck phrases, “What was that?” We continued to be focused on the safe ‘clean up’ of the aeroplane and Mike scanned the dials for any sign of trouble. There only seemed to be one slight ‘anomaly’.

Sitting at the bottom of the engine instrument stack sat a pair of vibration gauges. The right hand guage spoke on behalf of the No. 2 engine and was flickering around a reading of ‘2’ units. Per our checklists, no action was required until a reading of ‘4’ was evident and all other engine indications were normal. We were all aware, and wary, of information provided solely on the basis of vibration gauges. They had been integral in the loss of a 737-400 at Kegworth in England five years earlier when an engine failure had been misidentified and the incorrect engine shut down. The vibration guage only indicates a level of vibration in the fan, or front, section of the engine so as I flew the aircraft, Mike set about further investigation. He delved into the touch screen on the centre console known as the ACARS (Aircraft Communication And Reporting System) to reveal further details of the engine’s operation. Within the ACARS, the various stages of the engine revealed their individual levels of vibration and again, nothing stood out. As reflected by the guage, there was only a very slightly elevated level of vibration on the fan of the No. 2 engine. We discussed the option of returning to Melbourne but there was no justifiable indication to do so.

As we topped out in the climb and rolled over into level flight, the thrust levers retarded to the cruise setting and all evidence of the vibration disappeared. The vibration guage now read zero. With all seemingly back to normal, we reviewed the event and had another look at the ACARS; still nothing of consequence. We spoke to Engineering and they had nothing further to offer. On such a short sector we continued to manage the flight and pay attention to the housekeeping duties as the marker for top of descent steadily rolled down the Nav Display. As we pitched in to descent and idle thrust was set, we scanned the engine instruments again. Nothing. Zilch. Ops normal. I decided to delay my head scratching and concentrate on the descent profile for runway 05 at Adelaide which called for a crossing of the coast at Port Stanvac and, hopefully, a smooth decelerating arc over the water to intercept final approach. At that time, Ansett procedures had a minimum ‘spool up’ height of 800’ AGL. In essence, the most efficient descent saw the Boeing glide with the thrust levers at idle until the final stage of approach when, by 800’, the thrust levers were set for power on approach. On this sector my training was bearing fruit and the descent went very close to plan.

On final, wings level, configured and coming through about 1200’ I ‘clicked out’ the autothrottle and manually eased the thrust levers up to an appropriate N1. At about this time it felt like some one had started taking to the aircraft with a sledge hammer. The No. 2 vibration flicked full circle and seemed to bounce off the stops. In a blink, Mike called “taking over” and began to retard the right hand thrust lever back with some resultant relief. The runway loomed large, too late for checklists and a go-around seemed far from prudent. We entered the flare and Mike smoothly closed the thrust levers. The shudder was gone and we touched down right on the money as the Captain pulled asymmetric reverse, not wanting to risk the starboard engine. Clear of the runway, all indications were again normal, though we taxied to the terminal without raising No.2 above idle, just in case.

We parked at the bay and completed our shutdown checklists. The ground engineer plugged in his headsets with the accompanying eardrum rupturing ‘squawk’. Before we had an opportunity to say a word he opened up with, “You gotta see this.” The comment somewhat heightened our interest. After the passengers had disembarked we followed suit and made our way to the starboard nacelle. There was blood on the lip of the cowl indicating a bird strike, but further in a number of fan blades were badly bent. Three of them through almost 90 degrees so that they were pointing forward instead of running around the inner wall of the cowling. There was further biological evidence of the demise of a feathered being that, fortunately for us, had passed through the fan blades of the high-bypass engine but totally missed the engine’s core. This had been the ‘thump’ we had heard shortly after take off out of Melbourne.

Airframe and engine vibrations on board aircraft can be very difficult to diagnose. Their severity is often a combination of such things as airspeed, airflow angle, power settings, and the like. In the event of such vibration, many checklists call for a change in altitude, attitude and airspeed as a possible remedy. In our case, the approach configuration and body angle provided the correct mix for the vibration to fully manifest. Having said that, seeing the resultant damage also reflects the durability of modern jet engines, in this case the CFM56.
Perhaps one of the most valuable lessons that day lay in the nature of the engine problems. Prior to entering the airline world I had spent much of my time training pilots in engine failures of all descriptions. Single engine practice forced landings, engine failures after take off (EFATO) and asymmetric flight in all phases and corners of the envelope. The 737 conversion continued its engine failure emphasis with V1 cuts, engine fires, turbine seizures, failures in the cruise and so on. Almost exclusively, there was a distinct loss of power with resultant yaw. This was then followed by textbook procedures, resulting in a textbook outcome. The real world does not always throw up the standard scenario. It may be a partial loss of power, totally contradictory engine indications or any combination of conflicting information. Whatever the case, the first priority is to fly the aeroplane. Don’t rush in, take a breath and attempt to gather as much information as possible and then manage the situation. Many critical errors have been made in haste.

Until the final stage of the approach on our short journey from Melbourne to Adelaide, all we effectively experienced was a ‘bump’ and an ‘in tolerance’ vibration indication that subsequently disappeared. To see the fan blades of that starboard engine you would have expected far greater drama. We are all trained for when things go terribly wrong. We have drills, procedures and checklists in place to keep the most injured aeroplane aloft. Unfortunately reality doesn’t always fall within the guidelines of a syllabus. Be it the crippled DC10 at Sioux City or the more subtle confusion of Kegworth, neither were a ‘standard’ training scenario prior to the event. Certainly, on occasions emergencies are easily read and then again, sometimes it’s the little things.

Departing Broome. Isn't it great how some days just start out right?

We in the aviation world are actually a little further ahead of the game. We don’t give ourselves enough credit, but while corporate entities strive to maintain a level of secrecy, aviation seeks to share its shortcomings. The dissemination of safety findings on a global scale in an effort to circumvent repeat occurrences is one of our industries greatest achievements. When faults are found with aircraft, or the way in which we may operate them, that information is freely broadcast. It is a level of operational maturity that has not been achieved overnight, but it is a work in progress we can all be proud of.

Air safety investigation has come a long way over the decades. Rather than simply attributing every smoking wreck to “pilot error”, our knowledge based has broadened to delve deeper. We recognise that the finality of an accident is the result of numerous factors slipping through the net before ultimately combining in a lethal cocktail. The pilot is the final line of defence and sometimes he is just not enough. Sure, there are still instances of rogue pilots blatantly contravening every rule of good sense, but fortunately they are in the vast minority.

From ICAO and the national regulators of aviation down to individual operators, the pursuit of safety is an ever developing challenge. At its very core, success lies in open, honest reporting. Everyone has the ability to observe and speak up and in its most basic form; this is one of the places where safety begins. It may be wrapped grandly in a formal reporting system, or bound in the pages of an official accident report, but fundamentally it is about being honest. Whether it involves reporting potential safety issues or dissecting a tragedy in hindsight, there is no room for cover-ups or misplaced silence. Well chosen words may save lives.

But the road is not paved with gold just yet. There are still companies and cultures that do not encourage ‘speaking up’; whether on the flight deck or on a written form. In these environments, the benefits of safety have still yet to take full hold. Only when aviation professionals feel comfortable reporting mistakes and transmitting ideas can the group work together to minimise risks. Generally referred to as a “Just Culture”, it is an environment that encourages open communication without fear of reprisal.

So what does that mean to a lone pilot sitting in his Beechcraft Baron on a dark, wet threshold about to open the throttles?

It means that you are not alone. Somewhere before, a pilot has executed the same manoeuvre and contributed to the pool of knowledge that better prepares the next pilot. On such a dark wet night there are many dangers lurking. Sensory illusions due to acceleration trick the mind and only the instruments can be trusted. What if an engine should fail? Am I able to return to land or is there an escape path? Nearly every scenario that can be conjured has happened before and whether it culminated in a fatal crash or a moment of cold sweat, there is a lesson to be learned. The facts may be discovered by sifting through the wreckage or analysing a flight data recorder. Happily, they may also be found through self-reporting by a sensible, living, breathing pilot.

By whichever means the facts should surface, pilots should grab them with both hands. Aviation is an ongoing process of education and this is never more applicable than when we have the opportunity to read or the near misses and misfortunes of others. To the outsider this may appear ghoulish, but to those in the field it is cherished knowledge. Often sobering, these tales of misadventure fill the accident report sections of journals across the world.

It is equally important that we remain impartial as we digest the cold, hard facts. For in the safety of our armchairs it is impossible to recreate the mindset of another, or to feel the pressures and distractions that may have led to some terrible omission or oversight. It is not our place to judge with the benefit of hindsight, rather we should glean every ounce of knowledge that can be stored away for use on our own dark, wet night. Often, the pilot will have paid the ultimate price for a perfectly human error and there is nothing to be gained from slurring the reputation of another. In fact, such talk infers a sense of superiority and a belief that the mistake was merely simple and stupid. Beware! There is no room for such complacency in aviation.

I once watched a filmed re-enactment of the final approach of an ill-fated airliner. As the final stages of the approach became more hurried and communication more confused, error after error began to surface with increasing frequency. But rather than sitting in judgement, the hair rose on the back of my neck and a doomed sense of empathy with the crew stirred in my guts. I sat in air-conditioned comfort, knowing the final outcome of this approach, but I equally recognised the conditions that had placed this aircraft and all onboard in harm’s way. I could see the lurking demons of weather, systems failures, commercial pressure and fatigue stalking the hapless crew and I wanted to warn them from my comfortable chair. But it was all to no avail.

Far from sitting in judgement, I tried to take something from the tragic outcome that would improve my own operational performance. And so should we all when presented with safety information or the findings of an accident report. As with 'The Fatal Stall', from time to time this blog will re-visit a range of aircraft accident and incidents in an attempt to enhance the safeguards in our own flying. There will be no judgement placed on those who have ‘stared down the barrel’ in the accidents we review, rather we will endeavour to draw some positives from an otherwise unfortunate outcome. Nor will there be any sense of complacency, for there but for the grace of God, go I.

Being Prepared.

As with all emergencies, sound training before the event is vital. In the case of ditching, the training provided varies widely between operators. Often the degree of overwater operations will be a determining factor in the level of training provided. Whilst ditching training may be a core component of emergency training to off-shore helicopter operators, the same may not be true for those flying inland scenic flights.

It will always be impossible to train for absolutely every contingency in every emergency situation. Whilst budgets and time constraints may play a part, the varying scenarios of each emergency offer much too broad a spectrum to cover. Not to mention those events that our imaginations are still yet to conjure. As such, all emergency training is designed around regulatory requirements, training budgets and probability.

Airline training departments and aviation authorities design their syllabus to a background of risk management to assure that as wide a spectrum of non-normal situations as possible is covered. In turn, beyond the initial training, a recurrent program will provide ongoing training for the entire career of both flight and cabin crew.

The focus of training is linked to a factor of likelihood and by all accounts ditching falls into the ‘remote’ category for multi-engine jet transport operations. This is not purely a function aircraft engines’ ever-improving reliability or their safety in numbers. The regulations for over water operations are stringent and seek to ensure that the aircraft can at all times divert to an alternative airfield in the event of a critical systems failure.

Even so, it is a case of double jeopardy to lose ALL available engines and be forced to land on the water. The Hudson River case also proves that the aircraft doesn’t need to be over the middle of the Pacific Ocean to end up floating.

To this end, ditching training at airlines falls into a category of its own. The process of ditching is discussed at length in the manuals and crew training in emergency equipment, life rafts, evacuations and subsequent survival is ‘hands on’. Crews are scrutinised on these skills annually by both theoretical and practical examination. A failure to meet the regulatory body’s set standards results in the crew member receiving further training before they are allowed to return to line flying.

Yet in this stringent training environment, the training of pilots to fly the actual ditching manoeuvre in the simulator is not a mandated exercise by the FAA (US), UK CAA or CASA. That is not to say that individual operators do not include it in their syllabus of training, or that flight crews have not taken it upon themselves to rehearse for the eventuality during simulator training sessions. Simply, to date it has not been regulated. This may well stem from the risk assessment of the probability of ditching when compared to the incidence of other emergencies such as engine failure or depressurisation.

In a similar way, the thought of losing all four engines and their associated systems on a Boeing 747 was previously thought to be virtually impossible. Then in 1982, British Airways Flight 9 encountered volcanic ash over Indonesia with the subsequent loss of thrust on all engines. Again, the crew performed admirably in a situation beyond the scope of their training and manuals to ‘adapt, improvise and overcome’. Subsequently, the books were re-written, simulator training was updated and checklists modified. Today, pilot education of volcanic ash and its effects is routine.

This may well prove the case with ditching as well. Simulator exercises ‘reverse engineer’ the data from such incidents and use the lessons learnt to train pilots. With the data generated from US Airways Flight 1549, it is quite possible that a change in the training requirements in this area will be forthcoming.

Getting Out.

So many factors came in to play in the case of the Hudson River ditching, not the least of these being an experienced and well trained crew on both sides of the flight deck door. The two pilots had over 35,000 hours experience between them, while the three flight attendants had a total cumulative service in excess of 80 years!

For a successful outcome, the entire crew had to perform their designated roles to the best of their ability and, seemingly in this instance, at a level above. This was critical, not just in executing a successful ditching, but in safely evacuating 150 passengers.

Evacuations are generally described as prepared or unprepared, depending on whether the crew has had enough time to ready the cabin, its contents and passengers for the evacuation. It is also an opportunity to call for the donning of life jackets. The flight attendants would have had some advanced warning on Flight 1549, but it would have been minimal. Fortunately, as the aircraft had just lifted off, the catering carts and crew may well have still been secured away.

On coming to rest, the cabin crew is now faced with assessing the available exits, launching the rafts or slide rafts and evacuating the passengers with a minimum of time and panic. It is a fine balance to maintain order in the cabin while they undertake their duties and voicing loud, concise commands are central to organising the potential chaos. These are the very scenarios and drills that cabin crew train for year after year throughout their career.

A water landing presents the additional challenge of available exits. Notwithstanding fire, damage and extreme aircraft attitudes, in a land evacuation most exits are generally available. This is not necessarily the case when the aircraft is afloat. The attitude with which an aircraft settles on the water may preclude the use of certain exits, particularly the rear doors if the aircraft sits tail low and the door sill lies below the water line.

To further aid in keeping the hull watertight, the A320 also has a “Ditching Pushbutton” on the overhead panel. When activated, the guarded switch automatically closes valves and inlet doors which will lie below the water line.

The A320 is certified so that all doors and overwing exits can be used in a ditching and accordingly are equipped with escape slides. Despite this certification, it is a primary task of the crew that the viability of the exit is assessed before opening the door, as a door below the water line will allow the water to come flooding in and further impede the stricken aircraft struggling for buoyancy. Preventing over-zealous passengers from cracking these doors open in haste is yet another duty for the crew.

Opening the door will result in differing scenarios based on the aircraft type. For some aircraft, the escape slides double as life rafts, while others call for the crew to manually launch rafts that are stowed elsewhere in the cabin. Similarly, distress beacons can be integral to the rafts, or launched independently.  The evacuation is only started at an exit when these rafts are inflated and ready to accept passengers. It is also imperative that the life jackets are only inflated when clear of the aircraft. Another tragedy associated with the Ethiopian Airlines 767 ditching was the death of passengers within the aircraft having survived the impact. With their jackets already inflated, they floated to the aircraft ceiling and were unable to escape via an exit.

With doors open and the slides or rafts inflated, the passengers are shepherded towards the exits in a speedy manner to clear the aircraft before it can submerge. The crew will check the cabin again to ensure that all of the passengers have evacuated before being the last to exit. Once clear, survival and rescue become the next priorities. Again, the crew have been trained for contingencies varying from desert survival and dehydration to arctic hypothermia. The crew of Flight 1549 fortunately ditched close to land with a readily available flotilla to ferry the passengers to safety. Facing any significant time in the sub-zero waters may well have resulted in a different outcome.

It is said that cabin crew are there to provide the passengers with life saving assistance in an emergency. When the emergencies are not taking place, they are available to provide cabin service. This is not only a truism, but a very healthy mindset for all those involved with air transport. The crew of Flight 1549 and their wealth of experience emphasised the critical role to be played by those in the cabin in case of emergency.

In the Wake.

Being confronted with a multiple engine failure is the dread of any flight crew. To be further confronted with ditching the aircraft with only minutes to react is the stuff of worst case scenarios.

Yet events such as US Airways 1549 and the British Airways 747 left powerless by volcanic ash have proven that ‘worst case’ can on occasions become reality. The investigators will seek out the facts, volumes will be written and procedures modified. As proactive as aviation safety endeavours to be, sometimes  lessons have to be learnt from experience. Undoubtedly this will be the case again in the wake of the Hudson River ditching.

Fortunately, landing a jet transport aircraft on water is a rare event. Despite the mass of variables that can confront a crew and the time constraints that may be imposed by fate, training, experience and measured, appropriate responses can make the seemingly impossible survivable. It is a credit to the entire US Airways crew that all of the passengers went home to their families.

Safety briefing cards in the seat pockets and preflight presentations are provided with the hope that the actions contained therein are never required. In the same way flight and cabin crew train for most conceivable eventualities year after year, crossing their fingers that simulations are as close as they get. Yet time and again when the unthinkable has occurred, training has kicked in and the crew prove that they are up to the task.

The ability for a crew to ably fulfill their roles when confronted with an emergency is a function of both thorough training and the correct mindset under pressure. The landing of US Airways Flight 1549 on the Hudson River is testimony to this. These are invisible intangibles to the passengers as they board yet another routine flight, yet are possibly the most valuable component of the ticket price.

Should the unthinkable occur and their aircraft is faced with ditching, it will be this training, preparation and mindset that dictates whether they sink or swim.

Title Image. edp24.co.uk