If you fly with any regularity, you might notice a varying number of crew members on each flight. Understandably, the size of the airplane plays a major role in the decision of how many flight attendants are on a flight. However, FAA regulations how many flight attendants a plane requires at any one time. 

FAA regulations mandate one flight attendant per every 50 passengers, but airlines tend to staff more

As you might imagine, larger aircraft with hundreds of passengers require a minimum number of flight attendants. According to the Federal Aviation Administration (FAA), the flight-focused wing of the U.S. Department of Transportation, airlines must staff one flight attendant per 50 passengers.

For instance, the Airbus A380, the commercial aircraft with one of the largest crews can have as many as 21 flight attendants taking care of the aircraft’s passengers, per CNN Travel. And with an aircraft that large, it takes a sizable staff to keep the peace. Although an A380 can swallow up a maximum of 853 passengers, few airlines exceed 600 or so.

Conversely, tiny aircraft don’t require attendants at all. Simple Flying says the FAA mandates flight attendants on flights with between nine and 51 seats. However, as you might imagine, a flight with, say, 12 passengers requires just one flight attendant. 

While how many flight attendants are on a plane might seem like an arbitrary thing for the FAA to regulate, attendants do much more than hand out food and beverages. They play a pivotal role in onboard safety, from safety briefings to crew member instructions during an emergency situation. Moreover, crewmembers outside the cabin are part of the security of the aircraft. 

For instance, attendants may place the beverage trolley between the aisle and the cockpit to allow pilots to use the lavatory. This is a vital safety measure between any act of hostility and the time necessary for a federal air marshall to intervene.