Cosmic radiation on flights from Sydney (SYD) to Singapore (SIN)

How the sun changes the dose on SYD → SIN

The sun's 11-year cycle moves this number. With the same 7 h 52 min at 35,000 ft, the flight would have received 0.0173 mSv in April 2020, when the sun was quiet and more galactic cosmic rays reached the atmosphere, and 0.0144 mSv in January 2026, near solar maximum: 20% more at the quiet end. In August 2026 it is 0.0159 mSv.

How cruise altitude changes the dose

Flown at 31,000 ft instead, the same flight would receive 0.0119 mSv, 25% less than at 35,000 ft; at 41,000 ft it would receive 0.0218 mSv, 36% more. Same route, same time in the air, same month: only the air overhead changes.

Try it: change the altitude and the month

Every combination is its own CARI-7 run for SYD → SIN, with the same 7 h 52 min in the air. It is still a standard flight, not yours: the app calculates your exact flight.

The return flight: SIN → SYD

SIN → SYD receives 0.0149 mSv at 35,000 ft, 7% less than SYD → SIN, over about 7 h 20 min in the air against 7 h 52 min. The return is 32 min shorter: its track runs with the prevailing westerly winds at cruise altitude. Cosmic radiation builds up with every minute aloft, so the longer direction collects more of it along the same path.

Cosmic radiation on Singapore → Sydney flights

What 15.9 µSv compares with

The comparison values are the ones the FlightDose app uses.

Questions people ask

• AircrewHow much radiation do pilots and flight attendants get?
• Flight vs X-rayIs a flight more radiation than an X-ray?
• PregnancyIs the radiation from flying safe in pregnancy?
• Solar stormsDo solar storms make flying more dangerous?

All questions