(CNN) — Some passengers will arrive at the airport and find their flight is too full to allow for the neighboring seat to remain empty, according to data from a US airline industry group.
The group maintains, however, that the vast majority of flights continue to allow for many open seats, even as the average number of passengers on each plane is growing.
According to the group Airlines for America, 8.5% of flights are more than 70% full. .
That means about 482 daily flights are above the 70% mark. The group says US carriers are currently conducting about 5,670 passenger flights daily -- even after slashing thousands of flights from their schedules.
The 70% mark is significant because on a narrow body aircraft where most seats are in groups of 3, social distancing typically means using only two thirds of seats, or 67%.
When factoring in other types of aircraft and different seating arrangements, the International Air Transport Association says social distancing would mean using a maximum of 62% of seats fleet-wide.
There is no federal standard requiring airlines to leave empty seats and allow customers to socially distance, and the Department of Transportation recently instructed airlines that "if the passenger wishes to change or cancel due to concerns related to the Covid-19 public health emergency," the customer is not entitled to a refund or voucher.
Some airlines are making it easier to socially distance on flights, although their individual policies vary.
United has said it will notify customers whose flights appear to be more than 70% full in advance, and allow them to rebook if desired.
Southwest is capping the number of seats it sells to allow for empty middle seats. JetBlue said Wednesday it will keep middle seats empty, unless a group of travelers wants to sit together.
And Delta says it will add planes in order to limit them to 60% full.
The airlines say the majority of flights have ample space. Some 73% of flights last week departed with fewer than half of the seats occupied by passengers or crew, according to Airlines for America.
It said fewer than 1% of flights -- 0.7% -- were occupied between 90% and 100% full, a metric the airlines call load factor.
-- 3% of flights flew 80% to 89% full
-- 5% of flights flew 70% to 79% full.
-- 6% of flights flew 60% to 69% full.
--12% percent of flights flew 50% to 59% percent full
In January and February, the average flight carried between 85 to 100 passengers. Now, the average flight carries about 39 passengers. That number has climbed significantly from as low as 10 passengers per flight in April and 23 passengers per flight in early May.
"There's a strong sort of skewing here towards the empty part of the range," John Heimlich, Airlines for America's chief economist, told reporters on a conference call Wednesday. He and other officials on the call did not take any questions from reporters.
Transportation Security Administration data also shows passenger numbers climbing. It is now screening about 9% of the traffic it saw at the same time last year. That number dipped just below 3% one month ago.