The edge of a typhoon scraping Japan has forced the cancellation of practice for the Motegi MotoGP - the emergency choppers can't take off or land.MOTEGI, Japan - Japanese MotoGP organisers have drawn up contingency plans for the race weekend after rain and thick fog forced the cancellation of practice for what could be MotoGP's title-decider at the Twin Ring circuit.The Moto2 and Moto3 sessions were also wiped out after medical helicopters on standby for emergencies were unable to fly.Organisers 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.'NOT RUNNING WITH RISK'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. "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."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.Organisers 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.'SIGNIFICANT IMPROVEMENT'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 on the conditions witnessed so far," organisers said.Webb said the plan for Sunday, if Saturday were to be washed out, envisaged 40-minute qualifying sessions.It's the second race in a row to be beset by problems. The previous round in Australia saw races shortened and run with mandatory pit-stops for safety reasons due to rapid tyre degradation on the Phillip Island circuit.Bridgestone motorsport manager Hiroshi Yamada told reporters at Motegi that the supplier had brought extra-hard compound tyres 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 tyres.