A Practical Approach

Air New Zealand’s Queenstown RNP-AR approach with an HUD-equipped A320 is a unique operation and poses many challenges, particularly at night. Chris Long examines how the airline has overcome these using technology, training and an exemplary safety culture.

The overarching document on Required Navigation Procedure (RNP) is published by ICAO as Doc 9905 AN/471. In it the rationale for RNP AR is explained: “RNP AR APCH enables a higher level of navigation performance better able to address issues of airport access, such as obstacle-rich environments, and facilitate advances in air traffic management (ATM), (and) requires the operator to meet additional aircraft and aircrew requirements and obtain operational authorization from the State regulatory authority.”

When the challenges of one particular airfield included in the Air New Zealand destinations were analysed, it was recognised that this would be an ideal application of RNP AR procedures, but that, to ensure safe, commercial operation, a robust and comprehensive training regime had to be put in place. These procedures needed to be devised not only for the arrival, but also for the departures through that mountainous terrain.

The airfield in question, Queenstown on New Zealand’s South Island, has quite a few challenges. None of them are unique to it, but the combination of them all has, in the past, led to quite restrictive operation. The constant increase in popularity of this activity-oriented holiday destination has led to a big growth in demand, and that growth has become held back as a result of the limitations of the airfield operations.

As Captain Dave Wake, A320 Deputy Training Manager Queenstown Training SME explains, the issues which have affected arrivals and departures at Queenstown are (in no particular order of importance):

ZQN Circuit Procedure. Image credit: Jeppesen.

Night RNP AR Solution

Historic approach minima were typically 3000 ft. agl and therefore very limiting as they were based on VOR approaches. Initially only Day Operations were authorised, with no Night capability. The effect of RNP AR has been to reduce this minima significantly. Indeed, the most capable level of RNP AR is RNP 0.1, which notionally authorises approaches down to 250 ft. agl. In the Queenstown case, even though the equipment is operated to RNP 0.1 standard, this level is restricted to 400 f.t agl. At that height, the aircraft is offset from the centreline and requires visual realignment to complete the landing. This level of accuracy is imperative for nighttime operations, a desired capability.

Only Air New Zealand’s HUD equipped A320’s are able to fly this approach at Night. As part of Air New Zealand’s Operator Safety Case, a HUD was mandated as part of the package for Night Operations as it was considered on balance, to be beneficial for touchdown targeting and provide an increased level of safety. The A320’s are fitted with three Inertial Reference Systems (IRS), two GPS receivers and naturally, the two FMGCs. The Head Up Display (HUD) is only fitted to the captain’s station (LHS), with future A320 versions (NEO) having dual HUD installations. The display in the HUD is intuitive and is much like a standard ILS presentation except for the Lateral Deviation symbol, which is a rectangle, not a diamond. This allows the captain to fly an extremely accurate vertical profile, and the Final Approach Flight Path Angle Bars help to reduce the “black hole effect” seen on night-time approaches and to lead to precise touchdown targeting.

The airfield itself has been further upgraded for night operation with the widening of the runway to a standard 45 metre width and addition of full runway lighting.

Training

It is not unusual to find that, when such new technology and regulation lead to training as an “add-on” to existing licence privileges, crew training is to a minimum standard. Consequently, the understanding, competence and confidence of the crew does not always lead to the full and effective exploitation of the new capability.

Air New Zealand has a very firm policy that the training for this capability, day or night, should be to the highest standard, exceeding the minimum recommendations. The start point of course, is to select crews for night operations who already have experience in the daytime RNP operation. The training for that daytime operation includes a familiarisation flight aimed to help to understand the overall task. The initial day time full flight simulator (FFS) session covers area familiarisation and the basics of flying the instrument approaches into Queenstown and then local procedural and environmental constraints are gradually introduced and practiced. The final daytime FFS session places heavy emphasis on emergencies such as engine failure, double FCU/FMGC failure and unreliable airspeed procedure tailored for mountainous terrain. The triggers to a go-around during the procedure have to be thoroughly learnt and practiced - these have several variations depending on the height when initiated and must be clearly understood and positively carried out. The Captains then complete four entries and exits under supervision and the First Officers two, before the crews are released to day operation. A further constraint is currency - in the first 45 days the pilots must fly at least five entry and exits - that currency then extends to a 90-day period.

The RNP approach and configuration changes are started at 10,000 feet, and must be flown exclusively with full automation, and must have the Captain as the Pilot Flying (PF). The Captain’s role is to monitor the automation, to make the decision to assume manual control at Decision Altitude and complete the realignment for the hand-flown landing. The First Officer also monitors the approach, but it is in the division of responsibility that there are significant changes to the routine operations, and these are as a result of trials completed before the training package was defined.

These trials, referred to in an earlier CAT article in issue 2/2016, revealed with the assistance of eye trackers that captains, while manually flying the aircraft from DA to the runway, found judging the vertical profile to be far less challenging than correctly establishing on and maintaining the extended runway centerline. However, the reverse was found to be true for the First Officer. Air New Zealand has incorporated this discovery into its training. The result is a happy dependence of each pilot on the other. In essence, this is a necessary and formal incorporation of Crew Resource Management into the operation of the aircraft.

The conversion to a night-time qualification builds on a pilot’s Queenstown operating experience, to which is added a comprehensive training package. The basic requirement is that the pilots must have completed at least 30 arrivals and departures during daylight, and that their performance in routine FFS sessions has been to a high standard. The three-day course then consists of one day in the classroom, and two days in the FFS with at least 15 plus approaches to be flown (overtraining). Yes, that is more than the minimum, but it reinforces both competence and, importantly, confidence - and this pattern has proven to be highly successful.

Given that, by its very nature, RNP AR requires specific aircraft, flight crew and regulatory approval, it was imperative that the national authority be involved. In practice this meant very close cooperation with the New Zealand CAA, not only in the planning of the operation and training, but also in the formal approval. This worked very well, with a healthy working process which facilitated implementation. The first commercial night flight, NZ613, landed at Queenstown on 24 May 2016.

Results

Now entering its third season of operation, the results of this training and night time operation are being assessed. Importantly, close examination of the profiles has revealed that the carefully prepared procedures work well and have not required further modification. It is difficult to quantify the increased levels of safety, but these profiles show that there has been minimal deviation from the ideal planned approaches. This thorough training could well be judged to be both an operational and a commercial success.

Published in CAT issue 2/2018