JetBlue AirwaysIt urged flight attendants to show patience as it raced to recruit hundreds of employees in the midst of what it believes will be an unprecedented travel season.

“Please do not refuse an assignment you are assigned to operate; it is disruptive to the operation, lets down your fellow Crewmembers, and disappoints our Customers who rely on us to safely get them to their destination,” Ed Baklor, head of customer care and programs, said in an email to flight attendants, which was seen by CNBC.

The airlines were shocked at how quickly the demand for travel increased and now they’re trying to recruit thousands to deal with an increase in passenger numbers this spring and summer.

Airline CEOs this and last week told investors that they expect that strong demand — and customers’ willingness to pay more for tickets — will help cover the recent surge in fuel prices.

JetBlue’s Baklor informed crews, “We remain unprofitable even after two year and face increasing fuel prices and other inflationary forces that make it difficult for everyone.” We are expecting a strong summer, thanks to record-breaking hiring and consumer demand. If we have your patience and cooperation, this will be the flip side.

JetBlue did not immediately respond to our request for comment. However, Robin Hayes, CEO of JPMorgan stated last week at a JPMorgan conference that industry faces capacity limitations partly due to staffing.

Baklor informed crews that 700 pilots and flight attendants are on the way. Baklor also said that it is not just about hiring for peak times, but that there could be overstaffing in the seasonal lulls following the summer.

This week Alaska AirlinesThe union of flight attendants reached an agreement for double pay to flight attendants who fly over 100 flights per month. A pay unit is based on the length of each trip from May through June.