London, England (CNN) -- New measures go into effect at midday Tuesday that will let planes fly at higher ash densities than currently permitted.
As flight disruptions continue due to the ash cloud from an Icelandic volcano, the measures -- announced by the United Kingdom's Civil Aviation Authority on Monday -- are designed to ease the backlog.
Flights that operate in the so-called Time Limited Zone will be subject to time limits and stricter maintenance policies, the CAA said. Airlines must provide a safety agreement from their aircraft and engine manufacturers to receive clearance to the zone.
British airline Flybe will be the first to use the new zone starting Tuesday, the CAA said.
Major European airports reopened Monday after being closed for six hours due to the ash cloud.
The Monday cancellations were the latest in a round of weekend closures of airports across the United Kingdom and into continental Europe.
If the Eyjafjallajokull volcano continues to erupt at current levels and weather conditions prevail, air travel in Britain could be disrupted on Tuesday as well.
The problems began in mid-April, when the volcano beneath the Eyjafjallajokull glacier in southern Iceland erupted and sent a cloud of ash into the atmosphere, disrupting international travel for several days.
There's no way to know how long the volcano will continue spewing ash into the air, Georgia Tech scientist Josef Dufek told CNN on Monday.
"It could go on another year," he said, noting that an eruption lasted that long in 1820.
Volcanic ash can be a serious hazard to aircraft, reducing visibility, damaging flight controls and ultimately causing jet engines to fail.