The Fatal Stall. (Part Two) "Even The Mighty Can Fall." An Aviation Blog by Owen Zupp.

Owen Zupp - Thursday, February 16, 2012

                                                         

Those who have been following the blog will recall the chilling video that formed the nucleus of the post, 'The Fatal Stall'. In this instance, the aircraft involved was a light aircraft, but in recent times the tragic demise of Air France 447 has reinforced that size is not a barrier to the lethal nature of the stall. And yet, despite the publicity, Air France 447 was not the only airliner to fall victim to the edge of the aerodynamic envelope. Below is the story of another.

                

                          "Even the Mighty Can Fall"

 

The Boeing 727 is one of the all-time classic airliners. Built for speed, it is a pilot’s aeroplane that offers a hushed ride for its passengers by virtue of its three aft-mounted Pratt and Whitney engines which left most of its noise in its wake. Yet even such an illustrious machine can fall victim to the simplest oversight as the crew of Northwest Orient Flight 6231 learnt on a cold winter’s night in 1974.

Prelude to disaster.

The sector should have been little more than a milk run. The flight was a short positioning sector from New York’s JFK Airport to the upstate town of Buffalo where an American football team and its staff were awaiting a ride back home. The crew of three were the only occupants for the ferry flight on the evening of December 1st and consisted of the Captain, First Officer and Flight Engineer. The Captain had held a command for five years, while the F/E had around 2,000 hours in the back seat. The First Officer was to fly the sector and had previously been a Flight Engineer before changing to a ‘window seat’. Of his 1,500 hours as a pilot, only 50 of them were on the 727.

As the crew readied the Boeing, the forecast for the night ahead was typical of a cold winter’s eve on the east coast. The cloud base sitting at around 5,000 feet with occasional thunderstorms extending towards 30,000 feet and icing virtually assured for all levels in between. The crew had planned to cruise above the weather at 31,000 feet and had very little reason to believe that the flight would be anything other than routine. And yet in less than 15 minutes after departing JFK they would crash to earth in a forest a mere twenty miles to the north. But how?

The Tragedy.

Air Traffic Control’s first indication that a problem existed for Flight NW6231 came in the form of a Mayday call stating that they were, “...out of control and descending through 20,000 feet”. In response to ATC’s transmission, the crew’s final message was that they were, “...descending through 12....we’re in a stall.” In less than a minute they were dead.

The Boeing had hit the earth at high speed and its wreckage was confined to an area less than 50 metres square. There were some tailplane components a short distance away, but it was evident that these had separated in flight due to high aerodynamic loads. The undercarriage was retracted, but the leading edge devices were extended. While a number of the aircraft’s pitot heads had been damaged, two of the airspeed sensing systems were found to contain water and began to point the finger at possible icing issues. This was further reinforced when closer examination of the flight deck found the overhead ‘pitot heat’ switches were in the ‘OFF’ position.

Much more would be revealed when the aircraft’s Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) were analysed. As the flight was so short, both recorders contained voice and data recordings from before take-off to right up until impact and both portrayed a relatively normal flight prior to 16,000 feet. At this point the aircraft was established in the climb at 300 knots and climbing at 2,500 fpm enroute to cruise at FL310. Incredibly, the airspeed began to climb through 340 knots while the climb rate exceeded 5,000 fpm. The First Officer was taken aback by the increase; however the crew put it down to the aircraft being light and possibly an updraught associated with the forecast thunderstorms.

Incredibly, as they climbed the indicated performance was astronomical with a speed of more than 400 knots and 6,000 fpm rate of climb as the aircraft punched through 20,000 feet. Still hand flying the aeroplane the First Officer was continuing to pull back on the control column in a vain attempt to arrest the growing airspeed as the overspeed warning sounded. The Captain encouraged the new co-pilot to keep pulling back but it was all to no avail as the overspeed warning sounded again. And then, only seconds later, the stick-shaker activated to warn of an impending stall.

On the verge of 25,000 feet, the crew were still convinced that they were flying at excessive speed and rationalised that the stick-shaker was in fact Mach buffet at the other end of the performance envelope. The Captain again told his co-pilot to “Pull it up”. The gear warning horn chimed in, indicating that the gear was retracted while thrust levers were closed and idling at the stops. It was now all too much for the 727 and the airliner lurched from its nose high attitude to more than twenty degrees down as it simultaneously turned to the right through 180 degrees to point back in the direction of JFK. In an instant its rate of descent increased to 15,000 feet per minute. Yes, 15,000!

The aircraft continued its downward plunge and at around 12,000 feet the Captain recognised that the aircraft was stalled and called for “Flaps Two” as the stall warning continued intermittently. Ultimately the aircraft was descending with a 50 degree pitch down, 80 degree roll to starboard and a rate of descent of up to 18,000 feet per minute in association with G-Forces reaching 5G. Ironically. By this stage the airspeed indicator was reading zero as the tailplane partially failed under the load. The crew never stood a chance at this point and their fall from over 24,000 feet had taken a minute and twenty seconds.

 

                                

The Findings.

The attitude indicators were frozen at 20 degrees nose down at the point of impact, but it was what they were indicating a few minutes earlier that was crucially overlooked. Climbing through 16,000 feet when the incredible climb performance first began to accelerate, the pilot’s action was to increase the back pressure in an attempt to arrest the blistering speed. If due attention had been paid to the aircraft’s attitude, the nose was actually more than 30 degrees up, when a more likely attitude was in the realm of five degrees. Continuing to pull back only exacerbated the issue until the critical angle was exceeded and the aircraft stalled. So began the aircraft’s rapid fall to earth, but even so, there was no attempt to roll off the high bank angle as the aircraft descended so that any back pressure on the control column merely served to increase the G-loading. Everything was working against the crew possibly recovering the aeroplane.

But why would the crew receive such phenomenally high airspeed indications when in fact the aircraft was stalling with a high nose attitude and the thrust levers were closed? The simple answer is that the pitot heat had not been selected prior to take-off and the multiple probes had iced up until they were blocked passing 16,000 feet. The CVR revealed that there had been some hesitation, confusion and oversight when the pre-take-off checklist had been read, with the ultimate result that the pitot heat was not selected ‘on’. Such a simple error, but such an extreme result. The indicated airspeed was far from accurate once the system was blocked to the extent that when the aircraft stalled at 24,000 feet it was indicating over 400 knots but flying at less than 170 knots. Conversely, in the final stages of descent when there was zero indicated airspeed, the aircraft was probably flying in excess of 350 knots. Without due attention to attitude, confusion undoubtedly reigned supreme.

The Lessons Learnt.

For such a tragic outcome, the findings revealed that it was the failure to successfully complete a checklist that created the problem and an undue focus on airspeed rather than aircraft attitude that led to disaster.

The need for checklist discipline, whether for the lone pilot or the airline crew, is absolutely vital. Cockpit interruptions are frequent and distracting, but shouldn’t circumvent crucial checklists. If the flow of a checklist breaks down for any reason, there is a strong case to go back to the beginning and start it again. And then, don’t stow the checklist, move the marker or flip the page until the checklist is absolutely completed. Even if flying solo, recognise this point by stating out aloud, “Pre-take-off checklist complete.” It provides a further filter and is another marker in the brain that the job is done properly.

As for flying an aircraft with suspect instrument indications, the first thing is to consider whether the attitude and thrust setting is appropriate for the indicated performance. Confirm that the pitot or probe heat is selected to ‘ON’ and cross-check the Mach/airspeed indicators against each other as the fault may not lie across the entire system. First and foremost, consider the attitude and thrust in light of the performance.

The investigators did not find any great mystery in the loss of Northwest 6231. A simple oversight here and a misinterpretation there led to the catastrophic loss of an essentially serviceable Boeing 727 and its precious crew. Regardless of the size of the aircraft or the experience of the crew, the operation of any aeroplane is hinged upon discipline and the observation of some fundamental principles. This is sometimes easier said than done, so it is our responsibility as aviators to give due attention to every aspect of our operation and guard against the curve-balls that fate throws at us.

That cold night over New York the unfortunate crew saw events unfold at a rate that exceeded the ability to recognise what was befalling them and it all stemmed from failing to flick a switch. We are all only human and there but for the grace of God go I.

 

The full NTSB Accident Report for Flight 6231.

 

Title Image: r2suberti.blogspot.com

B727 Image. The extensive 'Ed Coates Collection'

The Practical Pilot. "The Comfort Zone" (Part Two) An Aviation Blog by Owen Zupp.

Owen Zupp - Wednesday, February 15, 2012

 

"The Comfort Zone" (Part Two)

 

Am I Orientated? (continued)

......BEFORE the weather even approaches the minimum levels for VFR flight, the pilot should have a clear picture of where they are and where they are going. This should include an awareness of the location and elevation of the highest terrain in the area and possibly setting a ‘personal’ minimum altitude based on that information. Remember, that sneaking up a valley in poor visibility can also be trap as power-lines may be draped between the ridge lines. Additionally, does this high terrain fall along the path of my pre-determined escape route?

As well as an awareness of potential landing fields, utilise all available navigation aids to support your visual navigation and refine your exact position. They will provide critical distance and bearing information to assist in interpreting what you see on your map. GPS is a tremendous tool in this instance, but also comes with the pitfalls of over-reliance and complacency for the visual pilot. (See "A Matter of Course")

Outside of the three dimensions of flight, a critical element of orientation is that of fuel and endurance. Fuel equates to time, distance and options. If we have the fuel, we may hold clear until the shower passes at the field, navigate around the offending weather or divert to another airport, possibly our point of departure. When the weather is approaching our ‘personal minimums’, fuel management can be overlooked as aviating and navigating consume a greater part of our brain-space. Running a tank dry, or worse, fuel exhaustion is the last thing we want to occur at this time.

Being orientated and situationally aware at all times is critical to the ongoing assessment required for visual flight. It is best appreciated continually when the weather is in our favour to allow earlier and safer in-flight decisions. Leaving anything to the last minute in aviation is not a good idea.

Am I Safe?

We have considered the legal minimums, reviewed our options, assessed our personal comfort level and appreciated our orientation. If we are not satisfied with any aspect of this exercise, we are pushing our limits and had better look at rectifying the situation. This is always best achieved sooner rather than later,

It is quite possible that the pressure is already beginning to mount by this stage and the age-old adage of AVIATE-NAVIGATE-COMMUNICATE should be remembered; fly the aeroplane! At this time, inadvertent entry into cloud, a loss of altitude or an unusual attitude could be catastrophic. A level 180 degree turn out of there may well be the safest option.

Visibility is critical. Rain and showers will reduce it below the minimum required in a flash. Flying with minimum separation from the cloud base also often results in poor visibility, so if the terrain permits, afford some more clearance from the cloud and its scrappy under-hang in an effort to see further ahead. But beware of lowering cloud and rising terrain leading to the classic trap.

Pre-flight cockpit organisation and a sound ongoing cycle of activity may prove to be one of your best friends. Reaching over to search for and tune up multiple frequencies and leaning down to look for a chart are sources of distraction from the primary task of flying the aeroplane. You should already be orientated and if you need one chart, it should be easily accessible and brought up to eye level to read. ‘Head down’ operations should be avoided at all costs. This is another reason why fuel management is important. Ideally you don’t want to be reaching down to change tanks at this time if it can be avoided.

Aviate-Navigate-Communicate. Fly the aeroplane first and maintain control. Assess terrain clearance and extricate the aircraft to a route clear of weather. It is better to divert early, rather than leaving it too late, “If in doubt, BUG OUT!”

Similarly, there is often resistance by pilots to ask for help, yet the sooner they are able to advise air traffic services, the possibility exists of radar vectors clear of terrain where the service is available. When out of the immediate harm’s way, double-check the management of fuel before it goes quiet 'up front' and ensure that the fuel is available to execute your new plan.

Of course, the flight would have been best served if these plans were in place from the outset and an early decision had prevented flight in deteriorating VMC.

In the Zone.

VFR flight is a genuine skill. As such, it needs to practised and honed just like any other skill. It is not easy, but that is one of the challenges of flying and a source of satisfaction.

Sound preparation and efficient management of the cockpit will aid greatly in offsetting the potential chaos. A sound ongoing cycle of activity will make sure that the house is in order the day when the weather foe comes knocking. Four questions at the heart of that cycle are;

Am I legal?
Am I comfortable?
Am I orientated?
Am I safe?

When the situation is deteriorating, these answers are not as straightforward and this is a sure-fire signal that action is needed. Execute any plan sooner rather than later and always Aviate-Navigate-Communicate.

By looking beyond the regulations and applying personal buffers, a greater margin of safety results. These ‘buffers’ do not need to be numerical in nature, they may simply be the fact that the evolving situation makes the pilot uncomfortable. By exercising prudent judgement and always placing safety at a premium, a greater level of enjoyment can be forthcoming from the tremendous endeavour of flight. And all the while remaining in our comfort zone.

 

Remember to check back for the next instalment in the 'Practical Pilot' series and don't forget to watch the short video of my flight around Australia. Just click here.

The Practical Pilot. Friendly Words of Warning.

The Practical Pilot. "The Comfort Zone" (Part One) An Aviation Blog by Owen Zupp.

Owen Zupp - Tuesday, February 14, 2012

 

 

The Comfort Zone

The rules of visual flight (VFR) are well stipulated and are designed to keep the non-instrument rated pilot out of harm’s way. However, the craft of successful VFR flight is more than merely measuring visibility or distance from cloud. It is about the ongoing assessment and application of a number of parameters beyond the regulations.

Am I Legal?

Safety in aviation should always be the foremost goal. Whether it is a quick scenic flight with friends or a trans-continental long haul flight with hundreds of fare-paying passengers, the primary obligation of the pilot is to ensure the safety of all on board. It is not an exercise in ego, or an absolute promise to arrive at the destination on schedule or even that day; it is about the duty of care for all on board and those whose roof-tops we overfly.

Through harsh lessons of the past and the ongoing review by governing authorities, guidelines and regulations have been established to point us in the right direction. However, there has never been a rule book, manual or computer program that is able to cover every scenario or cater to the varying levels of ability of the masses destined to apply the information. By their very nature, regulations tend towards the conservative side and rightly so; that is the safe thing to do. Yet even then the regulations may not be conservative enough for some individuals or situations and difficult to apply in the real world.

Visual Flight Rules are classic instance where the interpretation and application of a defined standard can prove difficult. They involve fixed parameters, calibrated in units of distance for in-flight visibility and the separation from cloud. Fixed units which are measured in the potentially highly dynamic air mass through which we fly at speed. Cloud bases fluctuate and visibility can shrink in the blink of an eye. This can be challenging stuff!

Furthermore, the average ability to gauge height and distance is, at best, marginal. One only has to look at the wide variation of responses from aircraft asked to report at 3 miles when there is no GPS or DME to assist them. To take this judgement and apply it to the fluid world of the weather raises the bar to a whole new level. 

Even so, as part of our cycle of activity, pilots must continually endeavour to assess the prevailing conditions against the legal requirements, bearing in mind that these are absolute minimums. Below these we are illegal; however, we were probably approaching an ‘uncomfortable’ situation some time before we actually reached the minimum requirements.

To safely operate in the visual flight regime, there is a need to not only strictly adhere to these pre-defined constraints, but tailor them to our own individual standards and the conditions that are set before us on the day. And all such tailoring MUST be applied on the CONSERVATIVE side of the equation as the countryside is marked with the wreckage of those who thought that their personal standards were better than the regulations.

                                          

Am I comfortable?

Flying should be enjoyable. Even when it is a paid profession, there should be a degree of gratification every time the world falls away from the wheels. That’s why we do it. There is very little fun to be had getting boxed into a corner which may ultimately cost your life. As such, one of the first and foremost questions a pilot should ask is, “Am I comfortable with this situation?”

This question can be applied to many aspects of aviation, but in the visual flight sense it rings particularly true as an early warning system. Generally speaking, well before the visibility drops to the minimum required or the fin starts cutting through the stratus, the heart rate will elevate and the hair on the back of the neck will start to twitch. This should serve as a signal to the pilot that they are starting to get towards the deep end of the pool; their feet may still be touching the bottom, but for how long?

The ‘comfort threshold’ will vary from person to person and change as the individual gains experience, hence the difficulty in applying a broad standard as defined by the regulations. The crosswind limit on an aeroplane may be 20 knots, but a lack of crosswind currency may render an inexperienced pilot to hesitate at going flying in those conditions. It would be legal, but would it be prudent? A dual check with an instructor would be a safer option and a sensible application of personal standards. In-flight weather is just the same. 5 kilometres visibility or 500 feet vertical separation may be legal, but may not be ‘comfortable’ to everyone.

In flight, at the first sign of discomfort with any particular scenario, the pilot should look at removing themselves from the situation or at the very least, critically review their circumstance and options. All VFR flight should be conducted with a ‘back door’, or a means of escape. It is foolhardy to continue towards deteriorating weather conditions but absolutely fraught with danger if the weather behind is also going bad.

Am I Orientated?

An escape route should be ever-present. At all times the VFR pilot should have a ready made answer for, “Where would I go if…?” When the rain is thrashing the windscreen or visual reference is silently lost in cloud, it is probably too late. Furthermore, the stress and workload of the situation will not permit the brain to offer the best resolution. Flailing charts and tuning radio aids knobs will rate a poor second to keeping the aircraft upright and out of harm’s way.

Continually through a VFR flight, the pilot should be aware of the nearest landing field and ensure that there is a clear route to it. It may be a private airfield, a farmer’s crop-duster strip or even a friendly paddock, but it is an option and ideally should not be released from clear access until another presents itself ahead, particularly when the weather is deteriorating. The field does not have to be in sight, but access to it must be apparent.  Even with 5km visibility, with no clear route to a landing field means that the pilot will be forced to possibly conduct a precautionary landing on an unprepared surface should the weather close in further.

To have suitable options and an escape route, it is vital that the pilot remains orientated and ‘situationally aware’. ‘Situational awareness’ can be defined as “…being aware of what is happening around you to understand how information, events, and your own actions will impact your goals and objectives, both now and in the near future”. To be aware of what is happening around you and how that may evolve requires the pilot to continually review the situation...........

Check back for Part Two of 'The Comfort Zone' and the next instalment in the 'Practical Pilot' series.

The Practical Pilot. Friendly Words of Warning.

A Flight Around Australia for the Royal Flying Doctor Service. An Aviation Blog Video by Owen Zupp.

Owen Zupp - Tuesday, February 14, 2012
                            

 

Hi All,

In 2010 I flew around Australia to raise funds for the Royal Flying Doctor Service.

Along the way I filmed the journey in HD and took a number of digital images. However, I also took a number of 'snaps' with my iPhone. I subsequently put these together as a short video for my own enjoyment, but given the interest being shown in this blog, I thought it might be a good time to share it.

Please spare a thought for the great work for the Royal Flying Doctor Service and if you're at all able, please spare a 'dollar for the Doctor'. Donate to the RFDS.

                                                       

Many thanks.

Cheers,

Owen 

                                                       

"Thor's Stepping Stones". An Aviation Blog Image by Owen Zupp.

Owen Zupp - Monday, February 13, 2012

Thor's Stepping Stones.

This line of storm cells made interesting viewing enroute from Sydney to Melbourne yesterday afternoon. With each growing cumulonimbus cloud building rapidly, they appeared to form the stepping stones for the 'God of Thunder' himself.

 

...and don't forget to visit the very popular blog titled 'Moments'

 

"Over the Nation's Capital." An Aviation Blog Image by Owen Zupp.

Owen Zupp - Saturday, February 11, 2012

   In flight over Australia's capital, Canberra, on my around Australia charity flight in 2010.

                                Photo: Paul Sadler, 'Australian Aviation' Magazine.

Queenstown. The Remarkable Challenge of RNP. (Part Two). An Aviation Blog by Owen Zupp.

Owen Zupp - Saturday, February 11, 2012

"Queenstown. The Remarkable Challenge of RNP", continues.......

Tools of Trade.

QANTAS operate the Boeing 737-800NG on its Queenstown route and of these 737s, only those equipped with the more powerful 26K engines are scheduled for the service.  Additionally, the aircraft is equipped with technology that is the envy of some of its bigger brothers. Beyond the glass cockpit and the satellite navigation at the heart of its RNP capability, the aircraft boasts a variety of new age equipment.

Of premium interest is the HGS, or ‘Head-Up’ Guidance System, a device which has long employed by military aircraft. The HGS provides a means of transposing vital flight information into the pilot’s primary field of vision, negating the need to alternate between an instrument scan within the cockpit and an external assessment of the flight-path ahead. This is achieved through a unit mounted above the Captain’s head, which in turn generates the information and symbology onto a transparent screen, or ‘combiner’, between the pilot’s face and the windscreen. An HGS Annunciator Panel on the First Officer’s side provides information about the HGS status and warning annunciations.

Via a panel on the centre pedestal between the pilots, numerous ‘modes’ can be selected for the HGS, varying the information presented to best suit the phase of flight. A wealth of information beyond that normally available from a traditional instrument panel can be overlaid on the world outside. An aim point can be placed upon the runway and flown to, the landing flare can be guided in both timing and rate, speed error tapes permit precise speed management and TCAS resolutions can be accurately flown with the eyes outside the flight deck. There is a myriad of purposes for this state of the art equipment, but fundamentally they all equate to more precise flying in all phases of flight with the eyes remaining safely ‘outside’.

Another piece of advanced equipment is the VSD, or Vertical Situation Display. A component of the EFIS instrument panel, the VSD can be selected to show the vertical profile of the aircraft, its projected flight-path and importantly, the terrain ahead. By offering a pictorial display of the aircraft’s vertical situation with direct reference to terrain offers an additional aid to situational awareness above and beyond the traditional map display.

The system is designed to alert the crew of any discrepancies that may compromise the integrity of the approach. Certain messages such as the loss of LNAV or VNAV information, or the actual navigation performance (ANP) failing to maintain the standard required highlight as bold messages across the pilot’s map displays. Additionally, as display functions, warnings annunciate when the pilot’s altimeter settings are in disagreement and the Navigation Performance Scales (NPS) also sum any cross-comparison errors to ensure containment is maintained. Protection also exists against barometric setting (QNH) errors on final approach by way of the display representing a vertical offset from the planned path.

The QANTAS 737NGs also feature an enhanced ground proximity warning system (EGPWS), that features a look-ahead alerting system as distinct to the older systems that offered warnings based upon a rate of closure and level of separation purely with the landscape directly below. The aircraft also has a predictive windshear function that can alert the crew of an impending event well in advance of the indications becoming obvious through conventional instrumentation.

Key to maximising performance in Queenstown operations is the Electronic Flight Bag (EFB). While company manuals are also held here in a digital form on this tough-built laptop computer, it is in the area of take-off and landing performance that the EFB is a critical tool for Queenstown. It allows the optimum figures for arrival and departure in a way that traditional manuals would struggle to match. This equates to the best possible outcomes for payload both into and out of a relatively performance-limited airfield.

For all of this investment in technology, the point is not wasted on the humans that must operate the systems. The pilots that operate into Queenstown for QANTAS are limited in numbers and form what is termed as the ‘Control Group’. The purpose of the Control Group is to ensure that pilot recency into Queenstown is maintained. Given the frequency of service and the challenges of the port, the goal is for pilots to operate to at least 3 times every two months to maintain a level of competency on the sector. Additionally, the crews operating to Queenstown undergo additional training above any mandated requirements, including additional simulator sessions and a mandatory day of ground school each year. Through limiting the numbers, it is also easier to disseminate any new information relating to Queenstown without delay. Landings are also limited to Control Group Captains at the New Zealand port. They undergo additional training which is staged through a defined syllabus which calls for a defined number of arrivals and simulator sessions before their approval is down to the lowest available minimum altitudes.

There is no denying the challenges of Queenstown operations, but as always the key to safety lies in a combination of both technology and the human factor. Both elements are well supported by the airline through the 737NG fleet and under the experienced, watchful eyes of Captains Ian Brinkworth and Alex Passerini.

 

       Turning 'Finals' Runway 05 at Queenstown. (S.Ruttley)

 

Flying the Route.

The QANTAS flights to Queenstown starts well in advance of the aircraft pushing back the international terminal. Flight dispatch and load control start looking at the possible prevailing conditions a couple of days before the flight. Similarly, most crews will start reviewing the situation the day before, particularly with reference to the anticipated weather, while an extensive briefing is provided by QMET on the morning of departure. The Integrated Operations Centre (IOC) is also critical in tying all the components together preflight, but also continues to monitor the flight and liaise with it throughout and provide timely information in relation to weather and anticipated payload ex-Queenstown.

Flight planning this ETOPS flight is a critical process as a change in runway surface conditions can have a significant effect on performance. Crews also carefully confirm the anticipated satellite coverage for arrival and departure as this directly impacts upon the level of RNP operations that can be conducted. As mentioned, regardless of the weather, the arrival is always planned with enough fuel to divert to another port, nominally Christchurch. Once at the aircraft, pre-flight is a busy time of verifying the validity of the EFB database, ensuring the additional overwater equipment is on board, tuning the HF radios and attending to the routine duties of the day’s first flight.

Not long after departure, the flight deck becomes quite a busy environment. The flight log is completed to check the ETA at Queenstown and this is then forwarded to both the company and the control tower via ACARS. The latest weather forecasts for all possible ports are obtained and the suitability to continue the ETOPS operation is confirmed. Much of this information gathering must be achieved in a timely manner before VHF ACARS coverage fades approaching top of climb, although the option of obtaining such information by HF radio still exists.

Enroute to Queenstown, the crew will inevitably calculate a number of varied conditions for both runways for their arrival using the EFB. Some considerations include, the maximum acceptable tailwind components for landing on each runway, the performance penalties imposed should the runway surface become wet, and a modified approach reference speed should the aircraft have been loaded with a slightly more aft centre of gravity. They will also endeavour to work through some limiting scenarios for departure based on the current conditions if time permits.

The arrival to Queenstown is thoroughly briefed and this often includes the consideration of alternate approaches to a degree. This is because the fluctuating weather conditions at the airfield and the traffic sequencing can sometimes avail a change to routing and the assigned RNP procedure. Invariably a maximum flap setting, Flap 40, landing is planned and non-normal and diversion contingencies are discussed. This is all completed well before top of descent to allow the crew to focus on the approach ahead.

Given the potentially strong winds and high peaks that surround Queenstown, the aircraft is invariably slowed down earlier and the passengers and crew seated to safeguard against any possibility of mechanical turbulence. While containment along the route laterally and vertical limitations are closely monitored, ground speed also warrants due attention. Strong tailwinds can mean that the ground-speed of the aircraft may spike the EGPWS system. As always, a conservative approach to configuration management offers the safest solution.

The Queenstown RNP arrivals in clear conditions are stunning, with initial phases taking in spectacular views of the peaks, ski-fields and waterways. For Runway 05, the latter stages are conducted in the shadow of the towering ‘Remarkables’ before a descending right turn over Lake Wakatipu brings the runway threshold clearly into view. For Runway 23, the aircraft begins its turn back to the airfield near the hamlet of Cromwell and flies down the valley. Passing beneath is Bungy Bridge where A.J. Hackett started the past-time of bungy-jumping while ahead on short final, the 737NG makes a smooth transition around one final hill before aligning with the runway, at which time the autopilot is normally disengaged.

Once at Queenstown, the departure calculations are made and via the EFB a range of flap settings up to Flap 25 are available. The weather for the return flight is checked and the fuel/payload equation is refined to optimise the commercial aspects. As with arrival, satellite performance is confirmed to maximise the performance of the aircraft in the RNP sphere. The 737NG can also be operated ‘bleeds off’ on departure with the APU managing the pressurisation and the air-conditioning of the aircraft. This permits the bleed air that would be servicing such tasks to be used for engine power and maximise performance.

The departure is equally spectacular as the 737 climbs to a safe altitude overhead before setting course. The aircraft is maintained in the take-off configuration with a limiting speed of 180 knots until it is established at a safe point and heading away from the terrain. All the while, a safe ‘escape plan’ is available to the crew immediately in the event of a non-normal situation.

With the terrain well below and the aircraft re-configured for the climb and cruise, the course is set for home. However, regardless of how many times this arrival and departure is flown, it never ceases to amaze the crews themselves.                    

Where to from here?

Queenstown has often been seen as the RNP test case by many. Across the world, including in the US Congress, the development of RNP operations by QANTAS has been watched with great interest. Yet Queenstown stands in many ways as a test case for the broader use of RNP. The same elements that ensure safety in challenging terrain are also beneficial in avoiding noise-sensitive areas and facilitating efficient idle-thrust descents at less challenging ports. The future also sees RNP approaches transitioning onto existing ILS and GLS approaches, but at much closer proximity to the airport, obviating the need for long final approaches of 10-15 miles as they currently require.

As ICAO moves towards its 2016 goal of providing vertical path guidance to all runways, the QANTAS operations showcase the technology to its fullest potential. As other airlines adopt the technology at a growing rate, RNP will ultimately become the norm. For other types, such as the venerable Boeing 767, the future also lies with RNP. QANTAS recently decided to upgrade 17 of its  767 fleet for ADSB which means they'll be able to fly RNP-AR starting next year. The same flight guidance system found in the 767 currently operates RNP into Lhasa
Airport in Tibet.

RNP technology has brought the accessibility of airline services to Queenstown with an enhanced level of safety and service reliability. In its 90th year, QANTAS may pause to reflect on nearly a century of airline operations, but just as exciting are the years that lie ahead.  Destinations like Queenstown increasingly demonstrate that with the right technology and the right training, the future is already here.

The Friday Flyer. An Aviation Blog by Owen Zupp.

Owen Zupp - Friday, February 10, 2012

 

Hi All,

Welcome to the ‘Friday Flyer’. The working week may be drawing to a close, but this blog just keeps humming along. This aviation blog continues to grow from strength to strength due to your ongoing support. The numerous positive comments and emails reinforce that the diverse and original aviation content is what you’re looking for, so I’ll continue to endeavour to provide it.

It’s been a busy week here at the aviation blog. There was a late night chat with the lads from PCDU for Episode 82 of their popular podcast. It is currently being edited and should be set for release next week. There was my first ‘Guest Blog’ at Airline Reporter regarding the Boeing 737.  These last few days also saw the first instalment of the new “Learning to Fly” series with "A Matter of Course" and this is set to become a popular ongoing series if the traffic numbers are any indication. As always there were interesting stories to complete for the upcoming edition of Australian Aviation.

As always, the new content is ever-popular, but some of the older posts continue to attract the visitors.

1. So You Want to be a Pilot?

2. The Fatal Stall

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

I am hard at work on my next manuscript and the good news is that it is nearing completion, so stay tuned for the latest news. One person who has completed the process and is celebrating the release of her first book is Karlene Pettit. An established aviation blogger from the United States, Karlene’s book "Flight for Control" hit the shelves this week. Congratulations! Having been through the process with "Down to Earth", I can truly share the excitement of seeing that first book ‘in the flesh’.

So what’s for next week? Another instalment in the “Learning to Fly” series and a look at another “Fatal Stall”. There will be the conclusion to "The Remarkable Queenstown RNP" and more original content and images. Thanks again for your support as it is your interest that keeps me writing. So tell your friends and spread the word and together we can share this journey of aviation.

Cheers for now,

Owen

Queenstown. The Remarkable Challenge of RNP. (Part One). An Aviation Blog by Owen Zupp.

Owen Zupp - Thursday, February 09, 2012

For over 90 years of aviation, QANTAS has been at the forefront of numerous technological advances. From the dawn of the jet age and the Boeing 707 to the certification of the Future Air Navigation System (FANS) was in 1995. Today the airline is once again at the cutting edge with advanced navigation development. Nowhere is this more evident than in its challenging operations into New Zealand’s Queenstown Airport where the latest technology has their Boeing 737-800s setting the pace.

A Remarkable Place.

As destinations go, they don’t come much more dramatic or scenic than Queenstown, New Zealand. The mountain range known as The Remarkables tower 7,500 feet above sea level and along with the surrounding peaks draw ski enthusiasts from around the globe. But there is more to the region’s beauty than its seasonal white blanket of snow. On a clear day, its dramatic peaks reflect in the glassy surface of Lake Wakatipu and it is easy to see why it was found suitable as the mythical “Middle Earth” in filming “The Lord of the Rings”.

It is undoubtedly one of the most beautiful areas around which to fly and this is further evidenced by the amazing amount of general aviation traffic that operates from the airport and the surrounding waterways. There are aerobatic joy-flights, parachute operations, scenic journeys to the nearby Milford Sound, heli-skiing and so much more, giving the region a distinct sense of aviation. Yet the location of Queenstown Airport (NZQN) is not what one may regard as geographically ideal for aviation.

The airport effectively sits in a natural bowl, surrounded by peaks and ridge lines. The terrain is not the only challenging aspect as the winds that swirl around the basin can vary significantly in both speed and direction at different levels. Even on a crystal clear day, the combination of traffic and terrain can make manoeuvring an airline category aircraft challenging, so any deterioration of weather conditions further contributes to the demands of making an approach or departure.

The airfield has long been serviced by traditional non-precision approaches and specific visual procedures; however they are less than ideal. The absence of vertical path guidance is one factor, while the inability to align the approaches with the runway or achieve an effective instrument approach are others.

At the bottom end of the instrument approach, the runway is 30 metres wide and a touch under 1800 metres in length, effectively limiting the port to operations by Boeing 737s and Airbus A320s. While a very proficient control tower is operational, there is no radar coverage, further increasing the tolerances required for procedural separation. However, in the near future, a Wide Area Multilateration system will be introduced to aid situational awareness.

In so many ways, operations to and from Queenstown can present a variety of challenges to crews. As a destination the enhanced safety and efficiency on offer through RNP operations elevated the profile of the South Island ski resort in the aviation world. If RNP could be proven to work here, then its overall potential and credibility could only grow.

The Right Approach.

RNP approaches dispense with the limiting rigid straight lines, arcs and trapezoidal obstacle clearance of traditional instrument approaches and departures. By maintaining an ‘area of containment’ relative to the designed track, it is possible to permit optimised routing, clear of terrain, noise sensitive areas and high density airspace.

In the case of Queenstown, terrain is the limiting factor. While the challenges of terrain are obvious, operationally it makes the design of conventional VOR approaches and departure procedures a very challenging task and this equates to higher instrument approach minimas. Higher minimas in turn equate to a lowered assurance of being able to become visual when weather descends upon the airfield and this impacts directly upon the commercial reliability of the service.

For example, the best case scenario for a traditional VOR approach minima into Queenstown is 4,600’ or around 3,400’ AGL. In comparison, the RNP-AR 0.1 onto Runway 05 as pioneered by QANTAS can achieve a minimum altitude of 1451’, or a mere 291’ AGL. Furthermore, the RNP-AR approaches establish the aircraft on final, stable and aligned with the runway. By comparison, the VOR approach still calls for some challenging manoeuvring within the basin to ultimately achieve a landing as the approach leaves the aircraft well above profile to effect a straight-in landing.

Similarly, on departure, the RNP calls for a minimum cloud base 300’, while the old-style departure tracks require a 4000’ ceiling or greater. Like the arrival, the departure provides both lateral and vertical guidance to maintain the aircraft within its safe area of containment as it climbs to achieve the minimum safe altitude (MSALT) of 10,600’ within 15 miles.

Even so, there are RNP approaches and there are RNP-AR approaches. The former are generic approaches designed under the limitations of PANS-OPS Doc 9905, while the latter ‘Authorisation-Required’ tailored approaches are designed by GE/Naverus in conjunction with QANTAS. However, both containing the critical element of vertical path guidance and position the aircraft favourably to conduct a landing. However, the improvements are not merely at the minimum altitudes, as the vertical path guidance offered by RNP approaches is also a significant safety enhancement.

At Queenstown, safety is also enhanced through RNP by the precise ‘engine-out’ procedures on offer. In the event of either an engine failure on departure, or a single-engine missed approach, the RNP offers a safe resolution despite the challenges of the surrounding terrain. The complex tracking is automatically availed to the crew through the FMC when the engine fails. They need only execute the modified routing and continue to fly the aircraft along the new track, ensuring containment at all times. As with normal RNP operations, judicious use of the autopilot provides the best means of ensuring flight within the specified tolerances, while managing the aircraft’s flight-path and configuration.  So much so, that its use is not simply preferred, but required beyond certain points on the approach and departure.

In the face of challenging conditions, the growth of RNP operations into Queenstown has offered not only greater schedule reliability, but an enhanced level of safety. Even so, nothing is ever taken for granted and all QANTAS aircraft operating to Queenstown are required to carry an alternate, regardless of the weather. Even with the best technology, aviation is a dynamic environment......

Check back for the conclusion of  Queenstown. The Remarkable Challenge of RNP.

This article first appeared in Australian Aviation Magazine.

 

The Practical Pilot. "A Matter of Course" (Part Two) An Aviation Blog by Owen Zupp.

Owen Zupp - Wednesday, February 08, 2012

"A Matter of Course" (Part Two)

.......The direct line “go to” function bypasses these waypoints and can stretch the sector length and consequently the time between any cycle of cockpit organisation. It can increase the period between radio calls and seduce single engine pilots over inhospitable terrain where their options are limited should the engine go silent. Even with a serviceable aircraft, rising hills can reduce the corridor beneath cloud  and add a further risk factor should the visibility drop and a 180 degree turn be called for. Even for flight in instrument conditions, the straight line can lead to higher LSALTs and lower freezing levels.

In fact, the apparent ease of GPS begs its use beyond its purpose. Some misguided pilots will ‘design’ their own instrument approach into their home port and fly unpublished approaches. Obviously these unsurveyed ‘approaches’ do not account for terrain in the splay, loss of an engine and adequate missed approach tolerances. Additionally, unqualified pilots have been caught out flying legitimate GPS approaches. Whilst this has also occurred in the past, the complexity of NDB and VOR approaches has provided a hurdle in many cases. GPS offers seemingly straight-in, runway aligned approaches to one and all at the touch of a button.

Even the ‘touch of a button’ can prove to be a trap. Visual flight calls for the vast majority of the pilot’s scan to be outside the cockpit. Impressive map displays and the need for data input drag that focus back into the cockpit and the expense of lookout. It leads to the pilot becoming ‘head down’ in a visual environment with increased risk of collision and reduced awareness of the surrounding terrain and potential forced landing fields.

It is a problem not limited to the VFR pilot. The rapid growth of technology in all areas of aviation has brought a new set of problems as humans interface with computers. Even the ‘big boys’ in multi-crew jets are prone to fixation and vulnerable to the errors of push-button data entry, The difference being that they often have rigid procedures in place to provide cross-checking and restricting ‘heads down’ operation in the terminal area. The single pilot doesn’t have this benefit.

The list of potential traps of GPS can go on. However, the benefits of the system undoubtedly outweigh these. It is the management of GPS, not the tool itself that generates the risks. GPS needs to be integrated into the visual pilot’s navigation toolbox; it is not designed to replace it.

Making it Work.

Used properly, GPS is the greatest aid to navigation available to the VFR pilot. It can provide a wealth of information at a moment’s notice. However, it needs to become part of the pilot’s overall navigation strategy, from pre-flight planning to post-flight review. Cross-checked and re-confirmed with the healthy mistrust that defines the situationally aware pilot.

In the planning phase, airmanship rather than expediency should always remain the determining factor. Even twin-engined airliners in the Flight Levels plan their route within range of alternate airfields in the event of engine failure or depressurisation. Look at potential waypoints enroute, navigable features, airfields and terrain with a view to them assisting your navigation and providing safe alternatives in the event of emergency. It can be surprising how few additional track miles are required to provide a significantly better route over ‘forced-landing friendly’ terrain.

GPS fits into this planning wonderfully with its ability to create waypoints along your route. Manually calculated tracks and distances can be cross-checked against those generated by the GPS when the waypoints are entered. Consequently, your navigation becomes an effective two-pronged attack in which visual reference and precision GPS complement each other.

Similarly enroute, the GPS information becomes a component of your cockpit cycle. Time, heading, fuel, track, log are all items that are re-assessed at regular intervals. By referencing the GPS within this cycle, its information can be directly compared to other navigational aspects and assists in avoiding fixation solely on GPS. This fixation can lead to dependency and that is when other supporting forms of navigation can fall away. An old rule is to confirm a landmark by three supporting features, perhaps a town, a rail junction and a river. Applying this to the GPS equipped cockpit, the GPS position can be one of these elements, but you still need to at least see the rail junction and the river.

It must always be remembered that it is visual navigation and the eyes remain outside the cockpit most of the time. This is not purely for the purpose of map-reading, but for collision avoidance and the ongoing assessment of weather. Not to mention that outside is where you’ll find the scenery too!

Post flight, the GPS generated data can be used to cross-check fuel consumption and what should remain in the tanks. As with the navigational aspects, calculate your long hand figure first so that the GPS figure doesn’t lead you to the same outcome by the power of suggestion.

GPS has revolutionised navigation. It has brought even the most basic cockpit blazing into the 21st century via a yoke-mounted moving map. It should always be treated with healthy caution as all interaction with automation must. Take care when entering data by small buttons in a dim cockpit and use gross error checks in advance to confirm the information generated for the pilot. Treat GPS with respect as a component of your navigational array and it will offer tremendous benefits.

Above all, you remain the pilot in command. The GPS is a tool for you to use and not the other way around. By adhering to the sound principles of navigation and airmanship, GPS will allow you to fly with a level of precision and assurance not previously experienced. Arriving overhead, on time and on track will simply be a matter of course.

Check back for the next in the ongoing "Practical Pilot" series and follow me via the RSS feed or Facebook for updates.

The Practical Pilot. Friendly Words of Warning.

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