Japanese Grand Prix organizers drew up contingency plans on Friday after rain and thick fog forced the cancellation of practice for what could be MotoGP's title-decider at the Twin Ring Motegi circuit.
The Moto2 and Moto3 sessions were also wiped out after medical helicopters on standby for emergencies were unable to fly safely in and out.
Organizers said they were considering dismantling one of the helicopters and transporting it by truck to the circuit, which is on high ground, where it would be reassembled.
The rules say two medical helicopters must be available at the circuit at all times. They are normally stationed five minutes flying time from the looped track.
"We are not prepared to run in these conditions when there is a risk that a seriously injured rider could not be given correct care," MotoGP race director Mike Webb said in a statement.
"The helicopter has been trying to get permission to fly to the circuit since Thursday and has even tried to take off and then been told to land again," he added.
"As soon as permission was granted... we would have given 10 minutes notice to the teams, but the helicopter was never given permission to fly."
The race is the penultimate round of the MotoGP championship, with Honda's Spanish rookie Marc Marquez poised to take the title despite being disqualified from the previous race in Australia.
The 20-year-old has an 18-point lead over reigning champion and compatriot Jorge Lorenzo, who rides for Yamaha.
Organizers said heavy rain was expected on Saturday morning but cloud cover should abate by the afternoon, which would allow the medical helicopter to operate and riders to get on track.
They added that in extreme circumstances, everything could be condensed into Sunday with practice and qualifying for all three classes shortly before the races.
"The weather on Sunday is forecast to be a significant improvement in comparison with the conditions witnessed so far," said the statement.
Webb said a contingency plan for Sunday, if Saturday were to be washed out, envisaged 40 minute qualifying sessions.
It was the second race in a row to be beset by problems. The previous round in Australia saw races shortened and run with mandatory pitstops for safety reasons due to rapid tire degradation on the Phillip Island circuit.
Bridgestone motorsport manager Hiroshi Yamada told reporters at Motegi that the supplier had brought extra-hard compounds to deal with a new track surface but had been caught out by the faster cornering speeds of the bikes.
He said Bridgestone would test at Phillip Island next year to ensure the safety and longevity of the 2014 tires.
(Reporting by Alan Baldwin; Editing by John O'Brien)