The US government wants to begin testing a program this summer that would allow low-risk frequent fliers to avoid extra security inspections at airports. Passengers could volunteer to pay a fee and submit to government background checks. If they are not found to be potential threats, they would avoid being randomly selected for the follow-up screening at checkpoints where carry-on bags pass through metal detectors. The aim is to move law-abiding and non-threatening travellers more quickly to their planes and permit screeners to focus more on people about whom the government has less information, said David Stone, acting chief of the Transportation Security Administration. The program, which will last 90 days could begin in June, is expected to appeal mostly to frequent travellers who would think the cost would be offset by the time saved at airports.