Mike Delta Xray

MDX had departed Coolangatta for Bankstown on August 9 1981 and was last seen on radar in the greater vicinity of the main ranges of the Barrington and Gloucester Tops approximately 95km north-north-west of Newcastle. No trace of the aircraft or its five occupants has ever been found.

Planned to fly a predominantly coastal route, the flight was conducted under night visual flight rules (NVFR) despite the aircraft and pilot being instrument flight rules (IFR)-certified. The pilot had more than 3,000 hours fixed-wing experience in a range of aircraft up to and including the DC-3.

Contrary to common beliefs, the weather along the route flown from Coolangatta was generally fine with clear skies, although it was a very dark night with strong south-westerly winds forecast. A cold front had passed through the area about nine hours earlier and a thunderstorm associated with this front was now well out to sea, although reportedly it still caused fluctuations of radio navigation aid indications. Cloud was forecast and reported as being limited to the western mountain tops with turbulence forecast and reported over the eastern sections of mountains and coast. This was due to these areas being downwind of the airflow disturbed by the roughly north-south oriented Great Dividing Range.

After Taree, MDX flew well west of its flight-planned track, being identified by Sydney air traffic control (ATC) approximately 36nm north of Singleton. At this time the pilot reported penetration of cloud and then almost immediately, failure of the aircraft’s primary altitude and heading instrumentation. At night, in icing conditions, with major instrument failures and caught in strong downdraughts, the aircraft was in peril.

From this radar position MDX turned south and was then radar observed in a slow turn to the east. Sydney ATC painted a final radar position of MDX approximately 5nm west to north-west of a waypoint known as Craven. MDX was fitted with an electronic locator transmitter (ELT), but airborne aircraft did not detect any signals shortly thereafter.

MDX was lost and to this day its exact location remains a mystery.

Could it happen again?

The ongoing search

An initial search launched immediately after the crash, guided by the then Department of Transport, lasted nine days. It involved numerous personnel, 4WD vehicles and agencies, including the Bushwalkers Search and Rescue (predecessor to Bushwalkers Wilderness Rescue Squad or BWRS), NSW Police, Fire Search and Rescue, SES and many more. The Army was present on the ground and in the air. Fixed-wing and rotary-wing aircraft together tallied over 360 hours aloft on the search with the former effectively covering the entire Barrington Tops and the helicopters focusing at lower level on the most probable positions.

Even a RAAF F-111 was tasked on two occasions to conduct a photographic and infrared linescan runs (for before and after for comparison), ‘Landsat’ satellite imagery was overviewed but resolution and search area coverage was inadequate. A RAAF Mirage was tasked to conduct a photographic mission although this appears to have been cancelled due to adverse weather.

Flying conditions for the search were appalling at times resulting in dangerous ice accumulation on aircraft and severe turbulence, and one search helicopter suffered delaminated rotor blades.

On the ground snow at higher altitudes could have made the predominantly cream-coloured MDX difficult to sight.

The foot search faced a three-pronged enemy in the terrain, the vegetation and the weather, elements which still hamper searchers today.

The NSW Police instigated another predominantly land-based search, Operation Barrington Tops, in September 1981 after waiting for better weather and consolidation of information. Again, BWRS and numerous other agencies were involved, but without success.

In the following years, BWRS and NSW Police Rescue personnel organised a great number of both official and unofficial searches.

Today, the search for MDX is a significant project for BWRS, although its primary role remains to conduct current searches under the direction of the NSW Police. The ongoing search for MDX falls between these prioritised searches but is never far from the minds of those involved.

BWRS’s search faces a number of challenges from steep terrain to topographic maps that do not show all the features as they are. Strong winds mean the constant threat of falling branches while thick vegetation slows searches significantly and makes it problematic in determining if an area is cleared. The canopy of vegetation is so thick that at times, airborne searchers cannot see searchers on the ground wearing high-vis clothing. Consequently, the use of a generously offered helicopter is not always appropriate.

Flying conditions for the search were appalling at times.

Modern remote sensing techniques are being used but the steep and heavily vegetated Barrington Ranges can result in a large number of ‘interest points’. Rocks, remnants of old gold mines and even fallen trees can generate valid looking points of interest – each of which then needs to be searched by foot.

BWRS’s new approach sees a combination of solid, open research supporting a truly coordinated, well-lead effort as having the greatest chance of success. Through a strong network of subject matter experts, witnesses and organisational relationships, a better understanding of the accident has resulted and misconceptions dispelled. This input along with some new approaches to analysing the information has moved BWRS’s main search area almost 10nm east of the traditional search area.

Many people have been involved in the search for MDX, committing a lot of time and effort, but to date the Barrington Tops still hold their secret.

Then and now

When MDX was lost in 1981, ground-based navigation aids were the primary means of navigation. Malcolm Fraser was the Prime Minister, handheld mobile phones were six years away from being publicly available in Australia, and the US Air Force had not long begun launching its NAVSTAR satellite constellation that would eventually give the world GPS.

Australia may have another Prime Minister named Malcolm, but much else has changed.

Air traffic controllers today operate radar equipment with vastly improved accuracy, availability and capability. There are now three en route radars in the area, rather than one, with the newer Cecil Park radar in Sydney siting on 450ft terrain which allows a considerably improved line of sight to the Barrington Ranges than the Sydney route surveillance radar (RSR) did in 1981. Also, rather than Sydney having to liaise with RAAF Base Williamtown for its radar information, Williamtown ATC radar information is now directly fed into the displays at Sydney. It is this communication between Williamtown ATC and Sydney that often leads to the common misconception that MDX was denied clearance to enter Williamtown’s airspace, thus sending the Cessna inland towards the higher terrain and ultimately instrument conditions. Transcripts show that a clearance through Williamtown airspace was immediately available. As MDX was NVFR, Sydney, in conducting its required duty held up the clearance to ensure that MDX would exit Williamtown airspace in suitable weather conditions for the NVFR flight category. An IFR Cessna 206 on almost the same route was less than 10 minutes ahead of the ill-fated MDX and proceeded through Williamtown airspace without delay. Several other civilian aircraft shown in the transcripts also easily operated through Williamtown airspace that night without delay.

Today, multilateration radar is a secondary surveillance radar (SSR) technique that uses more simple antenna systems than traditional mechanically or electronically rotating SSRs. Multilateration uses the principle of a single reply from an aircraft’s transponder from a number of these simple ground stations. The position of the aircraft is determined from the difference in arrival times of the reply and the geographical spread ground stations. However, these days radar is not the only surveillance tool.

ADS-B or extended squitter transmits accurate GNSS position and other information from the aircraft’s transponder regularly (every 0. 5 seconds) and is received by the more than 80 ADS-B ground stations strategically positioned across the country. ADS-B can also be received directly by other aircraft to give pilots visibility of other aircraft in their proximity – known as ADS-B In. Flying clubs and other interested parties can also receive ADS-B messages directly allowing them to keep an eye out on their aircraft fleet using numerous software and applications.

Along with positional information, the aircraft’s identification, barometric and GNSS altitudes, vertical rate, track angle, ground speed, ident if selected and any emergency codes selected are also added. ADS-B or multilateration ground stations then receive this information and add it to the mix of secondary and primary radar information for display. ADS-B or multilateration ground stations appear to be located at Williamtown, Point Lookout and Calga around the Barrington area. Despite these stations appearing to have the primary aim of offering redundancy to SSR coverage in the area, given their positions some increase in surveillance coverage would also be likely.

So, the contemporary air traffic controller in Sydney has a display seamlessly integrating information from multiple radars and ADS-B stations. There are also smart features such as ‘coasting’ whereby the system predicts an aircraft’s track for five sweeps following radar fade. The sensor fade position is also immediately discernible while all radar data is recorded. Comparing the equipment between now and in 1981 offers an appreciation of the challenges confronting the air traffic controllers involved with MDX.

Other technologies have also evolved in the past three decades. In 1981, ELTs were the exception rather than the rule. The Visual Flight Guide of the day stated that ELTs were only mandatory for specified flights over water, for those flights requiring the carriage of life rafts and for flights over or within designated remote areas, none of which applied to the fateful flight. Still, MDX did carry an ELT in the tail section that had automatic G-triggering ability, but no signal was detected on 121. 5MHz by aircraft overhead the Barringtons shortly after the accident.

A clearance through Williamtown airspace was immediately available.

MDX’s ELT possessed a 45-minute average detection time by passing satellites with positional accuracy in the order of 15-25km. Aircraft passing overhead could reduce the detection time, but if relying on satellites alone, many hours could pass before detection. Furthermore, at the time of the accident, the US National Oceanic and Atmospheric Administration (NOAA) stated that the automatic activation rate of ELTs occurred in only 12 per cent of aircraft crashes.

Today, a GPS-equipped 406MHz beacon allows a detection time of around four minutes with positional accuracies reducing to less than 100 metres. COSPAS/SARSAT still require that at least one satellite pass is required to confirm the GPS position, however, the relevant search authorities still receive the beacon’s transmission and position within minutes of activation allowing the commencement of the SAR process. Notwithstanding the benefits of 406MHz beacons, contemporary beacons still have the same major weaknesses that beacons had in 1981 – they need to be adequately maintained, stored, charged and tested.

On board, the light aircraft of 2016 are often equipped with different flight instrumentation offering different levels of redundancy. Rather than a vacuum pump-dependent system backed up potentially by an electric turn-coordinator, many modern aircraft have EFIS displays with multiple layers of backup. Furthermore, there is quite possibly an iPad on board providing yet another tier. And all of these devices have GPS-based moving map displays that can assist in providing instantaneous, accurate and easy-to-interpret location and ground speed information. Some even possess near real-time datalink weather presentations.

Aside from the dedicated aviation technology, there are a number of personal devices that are far more accessible in 2016. Personal locator beacons (PLBs) such as those used by bushwalkers are relatively inexpensive and available. Every second aviation enthusiast has a flight tracking app on their smartphone, watching the progress of any number of flights. There are also weather radar apps that not only display brewing weather, but wind velocity. And finally, everyone has a mobile phone. As has been seen in a number of accidents and incidents, mobile phones have been used by passengers to call during an event and the GPS data from the phone used to assist in locating individuals via their device.

Could it happen again?

One of the first rules of aviation is to never say never. Under that proviso, there is little doubt that the situation that confronted the pilot of MDX may be somewhat different in current times. Onboard equipment, supporting infrastructure and even personal devices may have aided the pilot in the gathering of information and the conduct of the flight.

That being said, once he was caught in icing and instrument conditions and at the mercy of downdraughts that exceeded his aircraft’s performance, the challenge was massive to say the very least. When further weighed down by an instrument failure, the possibility of a recovery was nearing the realms of impossibility.

In terms of subsequently locating the aircraft, many of the various technologies that would have assisted the pilot in avoiding the situation may well have also assisted in finding the final resting place of MDX and its occupants.

There will always be an analysis after the fact and the coffee-room quarterbacks will always have an opinion offered up from the security of a lounge chair. The conduct of a flight and the decisions made by a pilotin- command will always occur under the umbrella of the human factor, and consequently they will be subject to both the associated strengths and weaknesses of humankind. What exists now as opposed to 1981 are better tools to assist both the pilot and those on the ground to execute their duties, and should that fail, the ability to find and be found.

Listening to the audio of the pilot of MDX’s final transmissions is confronting. In a timeframe of mere minutes, the plight of the aircraft transitions from difficult to fatal and his words become few in number but increasingly frantic. It is sickening to hear and one can only imagine those last moments. And yet, we must still learn from those who are lost and in the case of MDX, a good many aspects of aviation have improved through the intervening years.

Even so, we are reminded of the potential fallibility of flight when an aircraft as large as a Boeing 777 can go missing as MH370 proved. However, while there are some remnants of the Malaysian airliner now drifting to shore, MDX still lies in the Barrington Tops, lost without trace. Still, both aircraft have dedicated men and machines looking for answers that may provide some solace and closure to the families. For everyone’s sake, we wish them well.

The author would like to acknowledge Glenn Strkalj and the Bushwalkers Wilderness Rescue Squad (BWRS) for their ongoing search for MDX and thank them for their assistance in writing this feature.