Plane Crash Diaries episode 26 – VOR confusion in 1986: The Tupolev-T134 crash that killed Mozambique President Samora Machel 

Samora Machel. ©Wikipedia.

The latest episode of Plane Crash Diaries focuses on one of the most conspiracy-theory speckled accidents in history, the October 1986 crash of a Tupolev TU-134 jetliner that was carrying Mozamibican president Samora Machel. 37 of the 43 aboard died. 

To say that the accident is shrouded in controversy is a bit like asking if Vladimir Putin thinks he’s Catherine the Great. 


This is one of those incidents where correlation does not prove causation unless of course you’re prone to conspiracy theories. 

A lot that could go wrong during a flight did on the Tupolev that day and it led to the death of a man who was a symbol of post-colonial rebellion. This amplified the conspiracy theory avalanche of course and has driven folks into paroxysms of perpetual pontification.

The plane deployed to transport Mozambique’s president that October day was a Tupolev manufactured in 1980 – registration C9-CAA. It had flown about 1,100 flying hours since it rolled off the production line and had undergone its last major inspection in August 1984 in the Soviet Union

Because it was October, there were no storms forecast as Samora Machel climbed aboard in Maputo for a flight to Mbala in northern Zambia earlier on the 19th to head off to meet Zambian president Kenneth Kaunda and Angolan President Eduardo dos Santos. The Tupolev headed over Zimbabwe then refuelled at Lusaka in Zambia, taking off once more routing to Mbala 1260 kilometers north of Lusaka. 

After a day of discussions they flew home at dusk.

At 20h46 on the return flight the radio operator made contact with Maputo Air Traffic Control reporting their position over central Mozambique and saying they were continuing towards Maputo VHF Omnidirectional Range the VOR navigation beacon. Just for those who don’t know A VOR (Very High Frequency Omnidirectional Range) signal is something like a lighthouse with two lights. One always shines through 360 degrees and can be picked-up wherever you may be in relation to it while a second conducts focused signal sweeps around the compass points at a set speed and you will only see this as it sweeps past your position. 

Maputo in centre using Google Earth Night mode. Extremely High altitude – note the lights. Although this is a modern image, in 1986 Maputo was a large City. The pilots appear to have ignored the weather note that clouds were 3/8ths and some of the city should have shone through. ©Google Earth.

The constant signal pulses when the narrow beam passes north which permits an instrument on board to calculate the plane’s position based on the phase difference between the pulse and the narrow signal’s appearance at your position. 

An instrument in the aircraft calculates where the aircraft is in relation to the VOR station using this phase calculation. 

A pilot can tune to a desired VOR station and set an instrument on the panel known as the Omni Bearing Selector (OBS) to indicate which direction the aircraft should be steered in order to reach the station. These days we use GNSS or GPS systems but that was those days. 

At that point the plane was maintaining an altitude of 35 000 feet then at 21h05 the crew radio’d Maputo to say they were ready to begin descent and approach. 

Maputo told them to descend and report reaching 3000 feet AGL or when the runway lights were in sight. The crew began their descent for an ILS or instrument approach to runway 23. That means they were going to perform a series of maneuvers operating under instrument flight rules from an initial point to a landing which is usually made visually. They would also arrive straight in, no turns or heading downwind or anything. 

As they descended, the plane suddenly turned 37º to the right – Westwards.

And the reason has been shrouded in mystery since then. The crew then thought that the Instrument Landing System and the Distance Measuring Equipment or DME at Maputo airport were not working as well.

We know it was.

So they were now heading towards the wrong VOR and their ILS setting they’d set and DME frequencies were now irrelevant. 

Shortly after 21h18 the plane reached 3000 feet on descent and the crew informed Maputo that they were maintaining altitude. This was the minimum safe altitude over Maputo and should have been maintained until the airfield was in sight. The aircraft was, however, not maintaining its altitude. Nobody picked this up on on the flight deck, or if they did, they ignored it. 

Still in descent mode, the aircraft was approaching the ground rapidly.

Tupolev TU-134 emergency checklist.

The Russians suggested later its because they were cleared to land that the crew continued their descent – which they hadn’t been, they’d been cleared for a visual approach but not to descend past 3000 feet. Of course all five crew members were Russian so there was a need to protect their nationals in what would be another terrible example of CFIT, Controlled Flight Into Terrain.

The plane hit the ground at 21h21 minutes  and 39 seconds approximately 35 nautical miles west of Maputo and into a hilly region at 2 185 feet, or 666 meters. The devils number had come into play once more – more grist for the conspiratorial mill. 

There was 3/8ths cloud cover at 1 800 feet. The visibility was 10 kilometers. 

Back in Maputo, the ATC looked out for Samora Machel’s flight in vain then alerted search and rescue. Of course they started by looking in the wrong place. Throughout the rest of the night and into the early morning the helicopters, planes and ground crews hunted around Maputo – even in Maputo Bay in case the plane had ditched. 

What set off the conspiratorial folks was the fact that the plane had crashed 150 meters inside South African territory– 500 feet. The left wing hit a tree and the plane slid down a hill in this remote and quite inaccessible part of South Africa. The plane broke up left a debris field over 2 200 feet, almost a kilometer long. Members of the Komatipoort police station in South Africa were alerted to the crash by a villager living at Mbuzini and they rushed to the scene. That was at around 11pm the night of the accident but the South Africans first had to decide what to do about telling the Mozambicans.

The first medical crew arrived at 1am, then at 4am a second medical support team flew in from Hoedspruit Air Force Base and evacuated survivors to Nelspruit hospital in the Republic. 

Four of the Mozambican cabin crew died along with 34 passengers. One survivor lingered on for 2 and a half months after the crash, before passing away. 

The SA Department of transport investigated the crash and they approached the US’s National Transportation Safety Board and the British Air Accidents Investigation Branch to assist. 

Memorial to the crew of the Tupolev TU-134 that crashed in Mozambique – in Russia. ©Wikipedia

Both refused so the South Africans hired three foreign investigators including aeronautical engineer Frank Borman who was a former US test pilot, astronaut and CEO of Eastern Airlines, Geoffrey Wilkinson, former head of the British Department of Transport’s Air Accident Investigation Branch and Sir Edward Eveleigh who was former Lord Justice of Appeal and member of the British Privy Council. 

Judge Cecil Margo chaired the six member body and the hearings were public between January 20th and 26th 1987. He’d soon chair another investigation into the crash of South Afrcan Airways flight 295 in 1988 – the Heidelberg accident we heard about in an earlier episode. 

The Machel inquiry rapidly threw out any suggestion of a bomb causing the crash and found that  the 37 degree turn was initiated by the navigator using the autopilot’s Doppler navigation mode.

That’s crucial. 

He did so because he saw a VOR signal indicating that the aircraft had intercepted Maputo’s VOR 45 degrees radial which is its compass direction from Maputo which the crew needed to intercept in order to approach to land on runway 23. 

What happened was the plane turned right onto the path of another VOR nearby which was thought to be the 45 degree radial at Matsapa Airport in Swaziland. But another allegation was made – that the SA Defence Force had placed a decoy VOR beacon on the ground and the pilots were flying towards that instead. 

The reason why it was likely however that Matsapa Airport VOR was the culprit is a simple matter of mistaken identity – the two VOR frequencies were almost criminally close – Maputo was 112.7 MHz and Matsapa in Swaziland was 112.3. Usually VOR signals that are adjacent have very different frequencies for obvious reasons.

Maputo Airport on left, Matsapa Airport on right. Distance 136km. ©Google Earth.

They did not cross-check at any point during approach so it was poor cockpit resource management. There were five of them, too many cooks were spoiling the flight to mix a metaphor. 

And then the big one – the crew knew they did not have sufficient fuel on board and could not make the alternative airport at Beira. This obviously increased the pressure on all five to continue approach into Maputo despite the obvious can of worms in the last few minutes. 

The final and deadliest mistake – they continued descending below 3000 feet despite only being cleared to 3000 and did so at a fairly brisk 500 feet per minute until just before they hit the ground. With a few seconds to go  the Captain did input a slight nose-up the pitch but hardly what we call a go-around. 

Had the crew performed the correct GPWS procedures when flying over hilly or unknown terrain by quickly raising the nose and increasing power they would have survived. 

Reading this makes no sense. Why did the Captain also fail to climb to the minimum safe altitude for Maputo of  3 600 feet when things began to go pear shaped? 

Just to finally deflate conspiracy theorists, SA Air Force pilots penetrated Mozambique air space over the next few weeks to test the Matsapa Swaziland VOR power and confirmed that it reached north of Maputo and could be picked up all the way down to 3000 feet on the same approach. This was further corroborated by a number of commercial pilots who flew on C9-CAAs track who also could read the Matsapa VOR.  

Just to really muddy the waters, the Mozambicans then cast around for a scapegoat and their baleful gaze landed on the unfortunate ATC by the name of Antonio Cardoso de Jesus. They accused him of  allegedly tampering with Maputo’s beacon on the night of the crash, being given a R1.5m bribe, a million US dollars in those days, by the South Africans and he was suspended in May 1988. Ten years later he told the Star Newspaper that he was leading a miserable life in Mozambique and could not say anything further. His superiors claimed he was suspended for ill health and not taking a bribe. So go figure. 

Maputo Airport. In the middle of residential areas even back in 1986. ©Google Earth.

Safety wise, this accident didn’t cause much international response other than the shock of a President of a country dying in a crash. However it reinforced the obvious need to ensure reserve fuel, proper CRM and adhering to checklists and approach procedure.  

The rule is clear, any modern commercial or airline crew would immediately know that this 45 minute reserve is dangerously close to the minima prescribed for aircraft operations. These minima state that sufficient fuel should be available to permit the aircraft to land at a suitable alternative airport when reaching the end of its journey plus 30 minutes worth of flying time. 

Their route took them over Zimbabwe and then central Mozambique. As they passed abeam of Beira, a decision would have had to be made to either continue to Maputo or to divert. They decided it was a go even though the fuel situation on board would have indicated that the crew would have a critical reserve once they reached Maputo. They had painted themselves into a corner. 

Where no alternative is available, then the 30 minutes of flying time becomes the minimum. The Russians skipped that rule and paid for it with their lives and so we must conclude that Moscow’s story of decoy’s is itself a decoy, a red herring. 

The Captain made one mistake after another and his biggest came at the end when he ignored the GPWS and refused to go around. 

Whatever decoys, red herrings, straw dolls, UFOs, nasty South Africans, blah blah cheesecake allegations, the truth is this. As a commercial pilot had he survived he would never have flown again. It was poor decision-making compounded by exhaustion and I’m afraid you don’t need a decoy to kill a president when his aviators are mucking around below minimums, clearly lost and debating who’s going to get which Heineken. 

Then they didn’t identify the VOR – another very old standard practice. They just twiddled the knobs and turned the plane. 

I was working as a journalist in South Africa at the time of this crash and remember vividly how we were extremely suspicious of the death of one of the most famous freedom struggle heroes of southern Africa. The apartheid government was pressurised from all sides, the Border War in Angola was heating up, the ANC’s internal political wing called the United Democratic Front had launched uprisings and Mozambique was allowing the ANC to use it’s territory as an insurgency jump-off point. The SA armed forces were indulging in torture, detention and brutalisation. Then suddenly Samora Machel dies in an aeroplane crash? Clearly suspicious. 

But correlation is not causation. 

This was CFIT through and through I’m afraid. Since then every few years some local social media crack-pot mutters about new evidence being found to prove a plot to kill Machel but its just the usual grandstanding mumbo-jumbo from that that coven of politicians otherwise known as a thicket.

Next episode we’ll focus on the US-Bangla Airlines Flight 211 accident in 2018. That was an example of some of the worst Cockpit Resource Management errors you will ever hear.

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