The STENDEC Puzzle

Ever since BSAA Avro Lancastrian Star Dust vanished on a flight from Buenos Aires to Santiago, the ending of its final transmission - STENDEC - has continued to puzzle experts and amateurs alike.

Star Dust, registration G-AGWH, an Avro 691 Lancastrian 3, departed Buenos Aires for Santiago at 13.46 on 2 August 1947.  It was not seen again until wreckage was discovered in 1998 by two mountaineers climbing Mount Tupungato.  The wreckage was found about 50 miles (80 km) east of Santiago.

What is missing from the many reports of the accident is the likelihood that the aircraft was fitted with radio aids to navigation or RDF - Radio Direction Finding equipment.  RDF was commonly fitted to long range passenger aircraft from the 1930s onwards, but as an absolute minimum Star Dust would have had the facility to home in on a radio transmission.  That is a method whereby a pilot simply aims his aircraft at a tranmitter and uses whatever signal is being transmitted as a homing beacon.

A Flight magazine report from August 1946 states that a navigation beacon had been set up near a weather station in the pass between Mendoza and Santiago.  The effective range of such beacons back in the 1940s was typically 100 miles.  Being in a pass or gorge it is likely incapable of being received by any aircraft which was not in line with the gorge.  Judging by the location of the wreckage it is unlikely that the aircraft was ever anywhere near enough to pick up the signal from the beacon.

It is clear from the official report that the pilot intended to fly the Mendoza - Santiago route at a height of 26,000 feet.  At this height the aircraft would have been flying some 4,500 feet higher than the highest peak in the region - Mount Tupungato.

The proven fact of flight into terrain may be taken as proof that the pilot had descended to about 15,000 feet in the belief that he had completely overflown the mountains.  The map below shows, approximately, the positions reported by the aircraft along its route.  Positions 1, 2 and 3 are likely accurate, or reasonably so.  Position 4 shows approximately where the pilot expected to find himself at 17:33.  It is worth noting that the pilot would have known about extreme turbulence caused as air flows over mountains and that he would have flown high to avoid it.  Sadly, the jet stream would have left him at position 5, or thereabouts.  It is likely that the radio operator, receiving a clear and strong signal from Santiago airport, assumed that the aircraft was much closer to the airport than it was in reality.  The 1741 signal reporting an ETA of 1745 indicates that the pilot thought he was quite close to the airport.

Homing in on Santiago airport radio and thinking he was slightly east of the airport, the pilot, who was actually some 50 miles east, flew into the mountain.

courtesy Google Maps.

The official report lists these transmissions:

1507 hrs. 33°55' S. 62°33' W. Height 10,000 feet, course 286°, speed 196 knots,
E.T.A. Santiago 1730 hrs.

1600 hrs. 33°25' S. 65°30' W. Height 10,000 feet, course 282°, speed 196 knots,
E.T.A. Santiago 1730 hrs.

1700 hrs. 32°50' S. 68°30' W. Height 20,000 feet, ascending to 24,000 feet, speed
194 knots, E.T.A. Santiago 1743 hrs.

1733 hrs. E.T.A. Santiago 1745 hrs.

1741 hrs. A signal was sent out by the aircraft, E.T.A. Santiago 1745 hrs. ending
with "STENDEC."

The 1741 hrs. signal was received by Santiago only 4 minutes before the E.T.A. The
Chilean Air Force operator at Santiago states that the reception of the signal was
loud and clear but that it was given out very fast. Not understanding the word
"STENDEC" he queried it and had the same word repeated by the aircraft twice in

A solution to the word "STENDEC" has not been found.

There have been very many opinions about the meaning of 'STENDEC'.  Beyond any doubt, any assumption that it is intended as an acronym is bound to be wrong, if only because there are millions of possible acronyms.  "Sacking Twenty Engineers Now Due Economic Crisis" is as likely as any other meaning - in other words not at all likely.

Occam's Razor is the best guide to the most likely solution to the puzzle.  That and context.  A simple  idea common to many suggestions from radio operators is that the message is 'something' END AR, where END means ending transmission / closing down and AR is the 'end of message' morse prosign.  Apparently, AR when sent fast is often mis-received as EC. 

AR is .-  .-.  and EC is .  -.-.

Context is everything.  Before assuming that 'ST' may be a misreading of the morse code it is best to try to determine what it might  mean in the whole context if 'ST' was actually intended.

Part of the situational context is that Buenos Aires and Santiago are in different time zones.  Currently Argentina and Chile both use UTC-3 as their common time zone.  However, at the material time Chile used two time zones, one for the central zone with Santiago and another for the rest of the country.

On August 27, Law No. 8,522 was published, which provided for the urgent change of time for Santiago and the central zone of the country, due to the inability of the plants to meet the demands of electric energy for industry, commerce, residences and Public lighting, leaving the capital and the central zone with the time zone of +3 hours and the rest of the country with a time zone +4 hours. Bulletin No. 20, notice No. 380/1946, dated October 31, 1946.
History of Chile Official Time
The mystery solved

1741 hrs. A signal was sent out by the aircraft, E.T.A. Santiago 1745 hrs. ending with "STENDEC."

The final message as sent was likely this:



Estimated Time of Arrival 17:45  Santiago Time  ENDing transmissions  signing off.


Further reading