The latest crash occurred on Monday morning in the canton of Uri when a Swiss Helicopter Group aircraft operated by an experienced pilot crashed near a Swiss Alpine Club above Erstfeld at around 9.45am.
All four occupants of the aircraft perished, including the pilot, two flight assistants and a mechanic, Markus Lerch, director of the group, told a press conference in Flüelen, the ATS news agency reported.
Cantonal police said all the victims all came from Uri.
The pilot had being flying from Ertsfeld for the past four years, the Swiss Helicopter Group said.
The aircraft, a Eurocopter, took off on Monday around 7am, headed for the Swiss Alpine Club cabin of Leutschach, at an altitude of 2,200 metres, to drop off a mechanic.
It subsequently flew to Andermatt before returning to pick up the mechanic.
Then the aircraft headed for another cabin, the Kröntenhütte, at an altitude of 1,903 metres but never arrived there.
The Swiss Helicopter Group was at a loss to explain what happened, ATS reported.
The company said the pilot was experienced, the helicopter was just one year old, and the weather conditions were good.
The accident followed another helicopter crash in Ticino on Saturday that left another four people dead, aged 43 to 63 years old.
Cantonal police said the incident on Saturday occurred near a granite quarry at Iragna in the northern part of the canton.
Two people, a passenger and a flight assistant, survived the crash, police said.
Police said the helicopter, with a 62-year-old pilot at the controls, was carrying four passengers to a mountain area north of Bellinzona.
The flight attendant and a passenger got out of the helicopter but before the craft took off its main rotor hit rock, for reasons that have yet to be explained, police said.
Instead of stopping, the pilot decided to return to base but he lost control of the aircraft and it crashed.
The pilot and three passengers, aged 43, 56 and 63, died on the spot, police said.
The Swiss Accident Investigation Board is looking into the causes of both crashes.