The phrase "request clearance" is correct and can be used in written English.
For example, you could write the following sentence: "I am writing to request clearance to proceed with the project."
However, with British Taekwondo yet to formalise their Rio selection policy he is concerned they would again overlook him and Cook has written to the British Olympic Association [BOA] to request clearance to compete for Moldova.
I dialed in the tower on my radio and prepared to request clearance.
Physicians can in future expect patients to ask questions and request clearance processes (such as fitness to fly certificates) for space travel as they do for commercial airplane flights today.
If there is an Air Traffic Control ATCC) unit, the pilot must request clearance for take-off.
Xbox requested clearance from the Securities and Exchange Commission yesterday.
Neither he nor the soldiers requested clearance for an airstrike.
Or - in the new world order - without requesting clearance from our two-year-old.
David Messing, a Continental spokesman, said that the airline had requested clearance from the Transportation Security Administration, the federal agency in charge of airport security.
The four-person crew, which Mr. Morozov said had been assembled a few days earlier and had received minimal emergency training, ignored the warnings and requested clearance for a landing attempt.
It's a noble dominion that extends vertically as far as the roof of our semi, and to my mind also includes the airspace above it - through which planes unaccountably continue to make their final descents into Heathrow without requesting clearance from me.
Updated 4 36 p.m. | Minutes before a single-engine plane crashed onto Interstate 287 in northern New Jersey last week, its pilot radioed air-traffic control to say that he was in "icing conditions" and requested clearance to climb higher, according to a preliminary report from the National Transportation Safety Board.
