Popocatepetl volcano causes Mexico flight chaos

US airlines have cancelled dozens of
flights into Mexico City over fears
that ash from a rumbling volcano
would affect their planes.
Delta and American were among the
airlines cancelling more than 40 flights
into the capital on Thursday.
Popocatepetl volcano has been rumbling
all year, and began spewing ash and
steam earlier in the week.
Airport authorities have kept the runway
open and say the volcano poses no risk
to flights.
"There is a very thin presence of ash,
which does not harm operations or
affect equipment," an unnamed airport
spokesman told AFP news agency.
The airport said US Airways, Delta,
United, American and Alaska Airlines
cancelled flights as a precaution.
The routes affected by the cancellations
were flights to Houston, Dallas, Denver,
Phoenix, Chicago and Los Angeles.
Mexican airlines are continuing to fly into
the airport as scheduled.
The authorities have established a 7-mile
(11km) no-go zone around the volcano,
which lies 40 miles south-east of the
airport.
It has been spewing ash and a fountain
of hot rock since May, and the alert level
is currently set one notch below
evacuation level.
Several tremors were reported around
the volcano on Thursday, but officials
said they had no immediate plans to raise
the alert level.