by mk

I think there's some bad information here.

Some pilots flew up to 33 sorties into the steam cloud, and six hundred helicopter pilots were killed by the radiation.

According to wikipedia, 600 pilots were involved.

Historians estimate that about 600 Soviet pilots risked dangerous levels of radiation to fly the thousands of flights needed to cover reactor No. 4 in this attempt to seal off radiation.

Doesn't really diminish their heroism, however.