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

How the sun changes the dose on SIN → SYD

The sun's 11-year cycle moves this number. With the same 7 h 20 min at 35,000 ft, the flight would have received 0.0162 mSv in April 2020, when the sun was quiet and more galactic cosmic rays reached the atmosphere, and 0.0135 mSv in January 2026, near solar maximum: 20% more at the quiet end. In August 2026 it is 0.0149 mSv.

How cruise altitude changes the dose

Flown at 31,000 ft instead, the same flight would receive 0.0112 mSv, 25% less than at 35,000 ft; at 41,000 ft it would receive 0.0204 mSv, 37% 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 SIN → SYD, with the same 7 h 20 min in the air. It is still a standard flight, not yours: the app calculates your exact flight.

The return flight: SYD → SIN

SYD → SIN receives 0.0159 mSv at 35,000 ft, 7% more than SIN → SYD, over about 7 h 52 min in the air against 7 h 20 min. The return takes 32 min longer: its track runs against 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 Sydney → Singapore flights

What 14.9 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