How FAA temporary flight restrictions work and why El Paso's disruption was different

• It is still unclear why the restriction order was not accompanied by assurances that there was no threat to public safety.

Read more about TFRs below.

What is a TFR?

How it works: A temporary flight restriction blocks access to certain airspace, like a city blocking a street, according to the FAA.

• TFRs restrict aircraft — often including drones — from operating without permission in specific areas for set periods.
• The TFRs are communicated to pilots through Notices to Airmen, which pilots are supposed to review before their flights.

When temporary flight restrictions are used

Context: On any given day, there could be several TFRs issued somewhere in the national airspace.

• The FAA's "Stadium TFR" specifically prohibits flying drones over some sports events.
• "VIP TFRs" protect movements of the president and vice presidents and can disrupt business and recreational aviation.
• "Special event TFRs" cover gatherings like the UN General Assembly and are often issued days in advance.
• TFRs are also used during wildfires, hurricanes or other emergencies and national security situations, the FAA says.

Reality check: Wednesday's shutdown was different than what America saw during the 9/11 airspace shutdown — when the FAA issued a nationwide shutdown of all U.S. airspace.

• Post-9/11, the U.S. established flying restrictions over Washington, D.C. — banning flights without special authorization.
• However, banning all flights over a major U.S. city as done Wednesday with El Paso has no modern precedent.

How to know if there's a TFR

The FAA publishes a real-time list of active TFRs.

• The FAA also has resources for drone flyers to see about TFRs, including the B4UFLY app.

Pilots who bust TFRs can face severe penalties, including "warnings or fines to certificate suspensions or revocations," per the FAA.

• Interception by military aircraft is also a possibility.